Acute respiratory tract infections and mannose-binding lectin insufficiency during early childhood

The Role of Mannose-Binding Lectin and Inflammatory Markers in Establishing the Course and Prognosis of Community-Acquired Pneumonia in Children

BACKGROUND

Community-acquired pneumonia (CAP) is one of the most significant childhood diseases worldwide and a leading infectious cause of death in children. This study aimed to evaluate the prognostic value of the inflammatory markers-C-reactive protein (CRP) and procalcitonin (PCT)-and the polymorphic glycoprotein mannose-binding lectin (MBL), deficiency of which is associated with severe infections, in the determination of the optimal type and timing of therapeutic intervention for CAP in childhood.

METHODS

Retrospective evaluation was conducted on a cohort of 204 children aged 4 months-17 years hospitalized with CAP. Their levels of CRP, PCT, and MBL were assessed for their association with a variety of outcomes, including the incidence of local and systemic complications, admission to the ICU, duration of antibiotic treatment and hospital stay, and death.

RESULTS

CRP and PCT proved to be better predictors of complications of CAP than MBL. The area under the curve (AUC) value was highest for PCT as a predictor of systemic complications (AUC = 0.931, 95%CI 0.895-0.967), while CRP (AUC = 0.674, 95%CI 0.586-0.761) performed best as a predictor of local complications (AUC = 0.674, 95%CI 0.586-0.761). Regarding admission to the ICU, CRP was the weakest predictor (AUC = 0.741), while PCT performed the best (AUC = 0.833), followed by MBL (AUC = 0.797). Sensitivity and specificity were calculated for the optimal threshold generated by receiver operating characteristic (ROC) curves, rendering sensitivity of 90% and specificity of 87% for PCT in assessing the risk of systemic complications, compared to sensitivity of 83% and specificity of 90% for CRP. MBL showed relatively high sensitivity (96%) but low specificity (25%) for predicting the need for ICU admission.

CONCLUSIONS

Early measurement of CRP, PCT, and MBL provides clinicians with important information regarding the course and prognosis of children diagnosed with CAP, thus ensuring prompt, optimal therapeutic management.

Ficolin-3 and MASP-2 gene variants in Siberian arctic populations: Summarized evidence of selective pressure for the high frequency of lectin complement pathway deficiency

Herewith, we provide novel original data about the prevalence of FCN3 rs532781899 and MASP2 rs72550870 variants among the newborns of aboriginal Siberian Arctic populations (Nenets and Dolgan-Nganasans) and Russians of East Siberia. This novel data has been analysed along with the genetic data about other proteins of the lectin pathway of the complement system (mannose-binding lectin and ficolin-2) obtained earlier. A total of 926 specimens of dried blood spots of the newborns were genotyped. The newborns represented four populations: Nenets, Dolgan-Nganasans, Mixed aboriginal population, and Russians (Caucasians) to study the prevalence of single nucleotide polymorphisms of FCN3 rs532781899 and MASP2 rs72550870. The prevalence of the deletion allele of the rs532781899 variant in the FCN3 gene associated with the decreased production of ficolin-3 was found to be increased in Russians compared to the Nenets aboriginal populations (P = .002). The prevalence of the rs72550870*G allele in the MASP2 gene associated with low serum protease activity was found to be increased in Russians compared with Nenets and Dolgan-Nganasans (P < .001 and P = .03, respectively). The results of the current study and our previous findings corroborate with a hypothesis that human evolution has been directed toward the accumulation of genotypes associated with low activity of the lectin complement activation pathway.

Mannose-binding lectin genotype is associated with respiratory disease in young children: A multicenter cohort study

BACKGROUND

Mannose-binding lectin (MBL) is an important component of the innate immune system. Polymorphisms in the MBL2 gene and promoter region are directly associated with MBL-deficiency. We sought to determine the association between MBL genotype on the frequency of common childhood respiratory infections, respiratory symptoms, and atopic outcomes in early childhood.

METHODS

MBL2 gene variants were analyzed in newborns recruited to the GO-CHILD multicenter prospective cohort study. Follow-up for respiratory infection and atopy diagnoses and symptoms, healthcare utilization, and medication prescription were conducted by postal questionnaires at 12 and 24 months.

RESULTS

Genotyping and follow-up were completed in 1004 children. Genotypes associated with MBL-deficiency were associated with an increased risk of bronchiolitis (relative risk [RR] 1.95, 95% confidence interval [CI] 1.33-2.85) and pneumonia (RR 2.46, 95% CI 1.16-5.22). MBL-deficient genotypes were associated with an increased risk of wheeze with shortness of breath episodes (RR 1.22, 95% CI 1.04-1.43), emergency department attendance (RR 1.90 95% CI 1.13-3.19), and hospital admission (RR 2.01, 95% CI 1.04-3.89) for wheeze. MBL-deficient genotypes were associated with a reduced risk of developing atopic dermatitis (RR 0.72, 95% CI 0.53-0.98).

CONCLUSION

The positive association between MBL-deficient genotypes and bronchiolitis and pneumonia, as well as a severe wheeze phenotype in some young children, supports the hypothesis that MBL is an important component of innate immunity in the vulnerable period before the maturation of the adaptive immune system. Identification of disease-modifying genotypes may help target preventative strategies in high-risk infants.

The relevance of complement in pemphigoid diseases: A critical appraisal

Pemphigoid diseases are autoimmune chronic inflammatory skin diseases, which are characterized by blistering of the skin and/or mucous membranes, and circulating and tissue-bound autoantibodies. The well-established pathomechanisms comprise autoantibodies targeting various structural proteins located at the dermal-epidermal junction, leading to complement factor binding and activation. Several effector cells are thus attracted and activated, which in turn inflict characteristic tissue damage and subepidermal blistering. Moreover, the detection of linear complement deposits in the skin is a diagnostic hallmark of all pemphigoid diseases. However, recent studies showed that blistering might also occur independently of complement. This review reassesses the importance of complement in pemphigoid diseases based on current research by contrasting and contextualizing data from in vitro, murine and human studies.

Proteomic Analysis of Potential Targets for Non-Response to Infliximab in Patients With Ulcerative Colitis

Background: Infliximab (IFX) is a potent therapeutic agent used for the treatment of conventional refractory ulcerative colitis (UC). However, the high non-response rate of IFX brings difficulties to clinical applications. In the context of proteomics research, our study of differentially expressed proteins (DEPs) is essential for non-response to IFX in UC patients and provides powerful insights into underlying drug resistance mechanisms.

Methods: A total of 12 UC patients were divided into responders to IFX (UCinfG), non-responders to IFX (UCinfL), severe UC (UCsevere) without an IFX treatment history, and mild UC (UCmild) without an IFX treatment history. Subsequently, DEPs were identified from intestinal biopsy tissue between responders and non-responders to IFX by a label-free proteomic quantitative approach, and the general principle of functional protein screening was followed to deduce the potential drug targets and predictors for non-response to IFX in UC patients. Meanwhile, these targets excluded DEPs caused by the severity of inflammation for the first time. The differential expressions of candidate protein targets were validated at the gene sequence level using GEO2R analysis of the GEO database and qRT-PCR in some independent cohorts.

Results: A total of 257 DEPs were screened out by mass spectrometry between UCinfG and UCinfL groups, excluding 22 DEPs caused by the severity of inflammation, and compared and verified at the gene sequence level in the Gene Expression Omnibus (GEO) database. Finally, five DEPs, including ACTBL2 (Q562R1), MBL2 (P11226), BPI (P17213), EIF3D (O15371), and CR1 (P17927), were identified as novel drug targets and predictive biomarkers for non-response to IFX. The drug targets were confirmed in the GEO database of the microarray results from three independent cohorts of 70 human intestinal biopsies and validated in qPCR data from 17 colonic mucosal biopsies. Among them, CR1 might affect the activation of the lectin pathway via complement-coated bacteria to play an opsonizing role in inflammation-related pathways closely associated with non-responders to IFX.

Conclusion: This is the first report of proteomics analysis for the identification of novel drug targets based on intestinal biopsy tissue, which is significant for hypotheses for mechanistic investigation that are responsible for non-response to IFX and the development of clinical new pharmaceutical drugs.

Association of mannose-binding lectin 2 gene polymorphisms with Guillain-Barré syndrome

Complement activation plays a critical role in the pathogenesis of Guillain-Barré syndrome (GBS), a debilitating immune-mediated neuropathy. Mannose-binding lectin (MBL) is a complement activation factor of lectin pathway which as genetic host factor may influence the susceptibility or severity of GBS. We investigated the frequency of MBL2 promoter (- 550H/L and - 221X/Y) and functional region (exon 1 A/O) polymorphisms and their association with disease susceptibility, clinical features and serum MBL among GBS patients (n = 300) and healthy controls (n = 300) in Bangladesh. The median patient age was 30 years (IQR: 18-42; males, 68%). MBL2 polymorphisms were not significantly associated with GBS susceptibility compared to healthy controls. HL heterozygosity in GBS patients was significantly associated with mild functional disability at enrolment (P = 0.0145, OR, 95% CI 2.1, 1.17-3.82). The HY, YA, HA and HYA heterozygous haplotypes were more common among mildly affected (P = 0.0067, P = 0.0086, P = 0.0075, P = 0.0032, respectively) than severely affected patients with GBS. Reduced serum MBL was significantly associated with the LL, OO and no HYA variants and GBS disease severity. No significant association was observed between MBL2 polymorphisms and electrophysiological variants, recent Campylobacter jejuni infection or anti-ganglioside (GM1) antibody responses in GBS. In conclusion, MBL2 gene polymorphisms are related to reduced serum MBL and associated with the severity of GBS.

Mannose-binding lectin levels and MBL2 gene polymorphisms are associated to dengue infection in Brazilian children at the early ages

BACKGROUND

The mannose-binding lectin (MBL) plays an important role in innate immunity. Genetically determined variations in serum levels of MBL may influence the susceptibility and clinical outcome of dengue infection in early life.

METHODS

We investigated MBL2 gene polymorphisms and serum levels of MBL (total and functional) in children with asymptomatic (n=17) and symptomatic (n=29), primary dengue infections, and age-matched uninfected children (n=84) enrolled in a Brazilian dengue birth cohort. Polymorphisms of the MBL2 gene were assessed by RT-PCR, while ELISA were used to quantify serum levels of MBL.

RESULTS

We found that the X allele and YX genotype in the MBL2 were more frequent in dengue cases than controls. Likewise, the LXPA haplotype was exclusively found in dengue cases, thus probably related to dengue infection in our setting. Moreover, we found a higher frequency of the O allele and AO genotype in control group. Serum levels of total and functional MBL were higher in dengue naïve infants than dengue cases.

CONCLUSIONS

MBL2 variants related to lower production of serum MBL were associated to dengue infection in infants, while intermediate to high levels of total and functional serum MBL were associated with protection. These findings highlight the role of MBL2 variants and serum levels of MBL in the susceptibility to dengue disease at early ages.

Inherited defects in the complement system

The complement system plays an essential role in both innate and adaptive immune responses. Any dysregulation in this system can disturb normal host defense and alter inflammatory response leading to both infections and autoimmune diseases. The complement system can be activated through three different pathways. Inherited complement deficiencies have been described for all complement components and their regulators. Despite being rare diseases, complement deficiencies are often severe, with a frequent onset during childhood. We provide an overview of clinical disorders related to these disorders and describe current diagnostic strategies required for their comprehensive characterization and management.

Identification of Aggravation-Predicting Gene Polymorphisms in Coronavirus Disease 2019 Patients Using a Candidate Gene Approach Associated With Multiple Phase Pathogenesis: A Study in a Japanese City of 1 Million People

The pathology caused by the coronavirus disease 2019 is mediated by host-mediated lung inflammation, driving severity, and mortality. Polymorphisms in genes encoding host inflammation and immune-related molecules may be associated with the development of serious pathologies, and identifying such gene polymorphisms may lead to the identification of therapeutic targets.

OBJECTIVES

We attempted to identify aggravation-predicting gene polymorphisms.

DESIGN

We use a candidate gene approach associated with multiple phase pathogenesis in coronavirus disease 2019 patients among a cohort in Hiroshima, a city with a population of 1 million, in Japan. DNA samples from the study populations were genotyped for 34 functional polymorphisms from 14 distinct candidate genes, which encode proteins related to viral cell entry, regulation of viral replication, innate immune modulators, regulatory cytokines, and effector cytokines.

SETTING AND PARTICIPANTS

Three core hospitals providing different services for patients with coronavirus disease 2019 under administrative control. A total of 230 patients with coronavirus disease 2019 were recruited from March 1, 2020, to March 31, 2021.

MAIN RESULTS AND MEASUREMENTS

Among the 14 genes, we found rs1131454 in OAS1 and rs1143627 in IL1B genes as independent genetic factors associated with disease severity (adjusted odds ratio = 7.1 and 4.6 in the dominant model, respectively). Furthermore, we investigated the effect of multiple phase pathogenesis of coronavirus disease 2019 with unbiased multifactor dimensionality reduction analysis and identified a four-gene model with rs1131454 (OAS1), rs1143627 (IL1B), rs2074192 (ACE2), and rs11003125 (MBL). By combining these polygenetic factors with polyclinical factors, including age, sex, higher body mass index, and the presence of diabetes and hypertension, we proposed a composite risk model with a high area under the curve, sensitivity, and probability (0.917, 96.4%, and 74.3%, respectively) in the receiver operating characteristic curve analysis.

CONCLUSIONS AND RELEVANCE

We successfully identified significant genetic factors in OAS1 and IL1B genes using a candidate gene approach study as valuable information for further mechanistic investigation and predictive model building.

Status of mannose-binding lectin (MBL) and complement system in COVID-19 patients and therapeutic applications of antiviral plant MBLs

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by a virus called "Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)." In the majority of patients, infection with COVID-19 may be asymptomatic or may cause only mild symptoms. However, in some patients, there can also be immunological problems, such as macrophage activation syndrome (CSS) that results in cytokine storm syndrome (CSS) and acute respiratory distress syndrome (ARDS). Comprehension of host-microbe communications is the critical aspect in the advancement of new therapeutics against infectious illnesses. Endogenous animal lectins, a class of proteins, may perceive non-self glycans found on microorganisms. Serum mannose-binding lectin (sMBL), as a part of the innate immune framework, recognizes a wide range of microbial microorganisms and activates complement cascade via an antibody-independent pathway. Although the molecular basis for the intensity of SARS-CoV-2 infection is not generally understood, scientific literature indicates that COVID-19 is correlated with unregulated activation of the complement in terms of disease severity. Disseminated intravascular coagulation (DIC), inflammation, and immune paralysis contribute to unregulated complement activation. Pre-existing genetic defects in MBL and their association with complement play a major role in immune response dysregulation caused by SARS-CoV-2. In order to generate anti-complement-based therapies in Covid-19, an understanding of sMBL in immune response to SARS-CoV-2 and complement is therefore essential. This review highlights the role of endogenous sMBL and complement activation during SARS-CoV-2 infection and their therapeutic management by various agents, mainly plant lectins, since antiviral mannose-binding plant lectins (pMBLs) offer potential applications in the prevention and control of viral infections.

The role of the lectin pathway of the complement system in SARS-CoV-2 lung injury

Although some evidence showed the activation of complement systems in COVID-19 patients, proinflammatory status and lectin pathway remain unclear. Thus, the present study aimed to demonstrate the role of MBL and ficolin-3 in the complement system activation and compared to pandemic Influenza A virus H1N1 subtype infection (H1N1pdm09) and control patients. A total of 27 lungs formalin-fixed paraffin-embedded samples (10 from H1N1 group, 6 from the COVID-19 group, and 11 from the control group) were analyzed by immunohistochemistry using anti-IL-6, TNF-alfa, CD163, MBL e FCN3 antibodies. Genotyping of target polymorphisms in the MBL2 gene was performed by real-time PCR. Proinflammatory cytokines such as IL-6 and TNF-alpha presented higher tissue expression in the COVID-19 group compared to H1N1 and control groups. The same results were observed for ICAM-1 tissue expression. Increased expression of the FCN3 was observed in the COVID-19 group and H1N1 group compared to the control group. The MBL tissue expression was higher in the COVID-19 group compared to H1N1 and control groups. The genotypes AA for rs180040 (G/A), GG for rs1800451 (G/A) and CC for rs5030737 (T/C) showed a higher prevalence in the COVID-19 group. The intense activation of the lectin pathway, with particular emphasis on the MBL pathway, together with endothelial dysfunction and a massive proinflammatory cytokines production, possibly lead to a worse outcome in patients infected with SARS-Cov-2. Moreover, 3 SNPs of our study presented genotypes that might be correlated with high MBL tissue expression in the COVID-19 pulmonary samples.

Interactions of genetic variants and prenatal stress in relation to the risk for recurrent respiratory infections in children

Genetic variants may predispose children to recurrent respiratory infections (RRIs) but studies on genotype-environment interaction are rare. We hypothesized that the risk for RRIs is elevated in children with innate immune gene variants, and that prenatal exposure to maternal psychological distress further increases the risk. In a birth cohort, children with RRIs (n = 96) were identified by the age of 24 months and compared with the remaining cohort children (n = 894). The risk for RRIs in children with preselected genetic variants and the interaction between maternal distress during pregnancy and child genotype were assessed with logistic regression. The IL6 minor allele G was associated with elevated risk for RRIs (OR 1.55; 95% CI 1.14-2.12). Overall, there was no interaction between maternal psychological distress and child genotype. Exploratory analyses showed that, the association between the variant type of IL6 and the risk for RRIs was dependent on prenatal exposure to maternal psychological distress in males (OR 1.96; 95% CI 1.04-3.67). Our study didn't find genotype-environment interaction between prenatal maternal distress and child genotype. Exploratory analyses suggest sex differences in gene-environment interaction related to susceptibility to RRIs.

The ambiguous role of mannose-binding lectin (MBL) in human immunity

Mannose-binding lectin (MBL) and lectin complement pathway have become targets of increasing clinical interest. Many aspects of MBL have been recently explored, including the structural properties that allow it to distinguish self from non-self/altered-self structures. Experimental evidences have declared the additional 5′- and 3′-variants that in amalgamation with well-known secretor polymorphisms change MBL function and concentration. Moreover, the current review highlights the differential behavior of MBL on exposure with extra/intracellular pathogens and in autoimmune diseases, stressing the fact that “high MBL levels can increase diseases susceptibility,” a paradox that needs justification. Attributable to these discrepancies, no absolute level of MBL deficiency could be defined so far and thus must be interpreted for specific diseases through case–control population-specific designs. Overall, it is evident that further research is needed about MBL and the lectin pathway of complement. Particularly, the transformative role of MBL over evolution is of interest and its role with regard to pathogenesis of different diseases and potential therapeutic targets within the respective pathways should be further explored. Apart from this, it is necessary to adopt an extensive locus-wide methodology to apprehend the clinical significance of MBL2 polymorphisms in a variety of infectious diseases by the future studies.

The Influence of the Lectin Pathway of Complement Activation on Infections of the Respiratory System

Lung diseases are among the leading causes of morbidity and mortality. Complement activation may prevent a variety of respiratory infections, but on the other hand, could exacerbate tissue damage or contribute to adverse side effects. In this review, the associations of factors specific for complement activation via the lectin pathway (LP) with infections of the respiratory system, from birth to adulthood, are discussed. The most extensive data concern mannose-binding lectin (MBL) which together with other collectins (collectin-10, collectin-11) and the ficolins (ficolin-1, ficolin-2, ficolin-3) belong to pattern-recognition molecules (PRM) specific for the LP. Those PRM form complexes with MBL-associated serine proteases (MASP-1, MASP-2, MASP-3) and related non-enzymatic factors (MAp19, MAp44). Beside diseases affecting humanity for centuries like tuberculosis or neonatal pneumonia, some recently published data concerning COVID-19 are summarized.

Familial and Environmental Risk Predisposition in Tonsillectomy: A Case-Control Study

Background

Tonsillectomy is one of the most commonly performed procedures among children and it is the gold standard management to reduce episodes of tonsillitis and obstructive symptoms. Many studies showed a significantly higher incidence of previous tonsillectomy in the parents and siblings. This study investigated the influence of familial and environmental trends in tonsillectomy.

Methods

Retrospectively, we identified those patients who underwent tonsillectomy (the case group). Also, a control group of participants attending the hospital as visitors who had not undergone tonsillectomy was collected. Both groups are compared using the proper statistical tests.

Results

This study included 1,232 participants; 615 underwent tonsillectomy (cases) and 617 did not (controls). It was found that paternal and maternal history of tonsillectomy, childhood asthma, and daycare attendance are independent factors influencing tonsillectomy in the offspring. Of about 85.4% of fathers who underwent tonsillectomy their children will also have tonsillectomy. Also, regarding the maternal history, 72.5% of offspring will have tonsillectomy if the mothers underwent the procedure.

Conclusion

This study reveals that genetic predisposition factors may have a role for tonsillectomy and its underlying causative indications. Also, it highlights the importance of asthma control in children. Moreover, the role of ethnicity may be minimal due to the similar trend of this study with other studies. Further studies and prospective research are recommended.

Epithelial dysfunction, respiratory infections and asthma: the importance of immunomodulation. A focus on OM-85

INTRODUCTION

Damage to the respiratory epithelium, is often a multifactorial phenomenon. The risk for developing a damage in respiratory epithelium and recurrent respiratory infections may vary among individuals. Preventive measures are based on strengthening the immune function, thus increasing the natural response to pathogens. Immunomodulatory agents are: i. synthetic molecules; ii. Probiotics, prebiotics, symbiotics; iii. Lysates, bacterial extracts immunomodulators: OM-85, RU 41740, D53; iv. Trace elements, vitamins. OM-85 is used for the prevention of recurrent respiratory tract infections and/or exacerbations both in adults and children, showing a good efficacy and safety profile. Its active principle, an extract of bacterial lysates isolated from 21 known respiratory pathogenic strains, shows protection against airway infections of bacterial and viral origin.

AREAS COVERED

This non-systematic review focuses on bacterial lysates and in particular on OM-85 and its effects on respiratory epithelium function and activity in asthma respiratory infections. Studies were selected by PubMed search of "bacterial lysate" or "OM-85" and "respiratory epithelium" or "respiratory infections", from 1993 to 2019.

EXPERT OPINION

Results highlight the ability of OM-85 to trigger immunomodulatory and protective immune responses against different pathogens in vivo, including influenza and respiratory syncytial virus as well bacterial superinfection following influenza.

Deciphering the Role of Host Genetics in Susceptibility to Severe COVID-19

Coronavirus disease-19 (COVID-19) describes a set of symptoms that develop following infection by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Whilst COVID-19 disease is most serious in patients with significant co-morbidities, the reason for healthy individuals succumbing to fulminant infection is largely unexplained. In this review, we discuss the most recent findings in terms of clinical features and the host immune response, and suggest candidate immune pathways that may be compromised in otherwise healthy individuals with fulminating COVID-19. On the basis of this early knowledge we reason a potential genetic effect on host immune response pathways leading to increased susceptibility to SARS-CoV-2 infection. Understanding these pathways may help not only in unraveling disease pathogenesis, but also in suggesting targets for therapy and prophylaxis. Importantly such insight should instruct efforts to identify those at increased risk in order to institute preventative measures, such as prophylactic medication and/or vaccination, when such opportunities arise in the later phases of the current pandemic or during future similar pandemics.

Serum mannose-binding lectin (MBL) concentrations are reduced in non-pregnant women with previous adverse pregnancy outcomes

Mannose-binding lectin (MBL) is an important component of the innate immunity, and it is responsible not only for opsonization of micro-organisms, but also for efferocytosis. The aim of this study was to investigate whether MBL concentrations and lectin complement pathway activity are altered in non-pregnant women with previous adverse pregnancy outcomes. Patients were divided into four groups on the basis of their history of pregnancy complications, including control patients who had uncomplicated pregnancies and term deliveries (control, n = 33), and three groups of patients with a history of pregnancy complications, including preterm labour (n = 29), recurrent miscarriage (n = 19) or unexplained intrauterine foetal death (IUFD; n = 17). All women enrolled in the study had an interval of three to six months following their previous pregnancy, and they agreed to have a blood sample taken. We found significantly higher MBL concentrations and functional activity of the lectin complement pathway in healthy controls who had previous uneventful term pregnancies (1341 ng/mL; activity 100% (IQR: 62%-100%)), compared to women with the history of IUFD (684 ng/mL, P = .008; activity 8.5% (IQR: 0%-97.8%), P = .011), recurrent miscarriage (524 ng/mL, P = .022; activity 44% (IQR: 4%-83%), P = .011) or preterm labour (799 ng/mL, P = .022; activity 62.5% (IQR: 0%-83%), P = .003). Our results suggest that inadequate function of the complement lectin pathway is associated with a higher risk of preterm labour, recurrent miscarriage and unexplained intrauterine foetal death.

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.

MicroRNA-548 regulates high mobility group box 1 expression in patients with preterm birth and chorioamnionitis

High mobility group box 1 (HMGB1) is a prototypic alarmin and plays an important role in the pathogenesis of inflammatory process in spontaneous preterm birth. This study was conducted to compare the levels of HMGB1 in amniotic fluid and amnion membranes in women with chorioamnionitis/intra-amniotic inflammation to the levels in healthy controls. We also aimed to elucidate the involvement of microRNA-548 (miR-548) in regulating HMGB1 expression and its function in human amniotic epithelial cells (hAECs). A bioinformatics analysis predicted the binding of HMGB1 by the miR-548 cluster. A repressed and forced expression assay in hAECs was performed to investigate the causal relationship between the miR-548 cluster and HMGB1. The levels of HMGB1 in amniotic fluid and amnion membranes were significantly higher in patients with intra-amniotic inflammation/chorioamnionitis than in those without inflammation. The miR-548 was significantly under-expressed in amnion membranes from patients with chorioamnionitis than in normal term controls. Repressed expression of miR-548 up-regulated HMGB1 expression in hAECs and increased its release from hAECs. Moreover, forced expression of miR-548 suppressed HMGB1 and inflammatory cytokines in hAECs, which increased when treated with lipopolysaccharide. These results suggest miR-548 can alter the inflammatory responses in hAECs, and might be involved in the pathogenesis of preterm birth by regulating HMGB1.

The impact of mannose-binding lectin polymorphisms on lung function in primary ciliary dyskinesia

OBJECTIVE

Primary ciliary dyskinesia (PCD) is a congenital lung disease that leads to recurrent and chronic lung infection. The resulting inflammation causes lung damage and declines in lung function. Mannose-binding lectin (MBL) is a first line host defense protein of importance for the innate immunity. Polymorphisms in the MBL gene named MBL2 result in unstable and low functional levels MBL proteins. MBL insufficiency is linked to an increased risk of lung infection and to declines in lung function in patients with cystic fibrosis. We investigated whether there is a similar link in patients with PCD.

METHODS

This retrospective longitudinal study included 85 patients with PCD. Diagnostics and age at diagnosis were recorded, complete spirometry data starting at diagnosis, and Pseudomonas aeruginosa infection status over the last 2 years were collected, and the patients were grouped according to MBL2 genotype status (MBL2-sufficient or MBL2-deficient).

RESULTS

MBL-deficient patients were diagnosed almost 3 years earlier than MBL-sufficient patients (median 6.1 vs 8.9 years, P  < 0.05). There were no differences in the first measured spirometry values, but MBL-deficient patients showed greater declines in forced expiratory volume in one sec (FEV₁ ) than patients with MBL sufficiency (z-score: -0.049 per year [95% CI, -0.075; -0.021] vs -0.009 per year [95% CI, -0.033; 0.015]; P = 0.023). No differences were found in forced vital capacity (FVC), FEV₁ /FVC, or infection status.

CONCLUSION

MBL-deficiency, which is associated with MBL2 mutations, was associated with a lower age at diagnosis and with steeper declines in FEV₁ in patients with PCD. This suggests that the MBL genotype might be a disease modifier in PCD.

Prognostic Value of MMP-9 -1562 C/T Gene Polymorphism in Patients With Sepsis

Introduction:

Matrix metalloproteinase-9 (MMP-9) plays an important role in the pathophysiology of sepsis. A single-nucleotide polymorphism (SNP) at position -1562 (C/T) in the MMP-9 gene has been associated with differential MMP-9 expression, being higher when the -1562 T allele is present. We evaluated the association of the SNP MMP9 -1562 C/T with severity and mortality in patients with sepsis to establish whether the prognosis of the disease is affected.

Materials and Methods:

A case-control study exploratory was carried out in a cohort of infected patients. 540 individuals were selected in total, 270 patients with sepsis and 270 controls (infected but non-septic), classified according to the 2016 consensus (Sepsis-3). The presence of the single-nucleotide polymorphism (SNP; allele T and/or allele C) was determined through analyses of restriction fragment length polymorphism and plasma levels of MMP-9 were determined through enzyme-linked immunosorbent assay immunoassay.

Results:

SNP MMP-9 -1562 has two known alleles (T and C), with predominance of the C over the T allele; in the group of patients with sepsis, T allele was found in 7.2% of cases, while C allele in the rest (92.8%); in comparison, in the group of infected but non-septic patients, frequencies were 9.4% for T allele and 90.6% for the C allele (P = .33). Also, the presence of the polymorphic T allele was not related to the levels of MMP-9 in patients with sepsis in comparison with infected but non-septic patients 780 (397-1375) ng/mL vs 646 (172-1249) ng/mL (P = .64). There was also no association between the SNP and sepsis mortality (P = .78).

Conclusions:

We concluded that there was no association between the SNP MMP9 -1562 C/T and sepsis or between the SNP MMP9 -1562 C/T and sepsis mortality in the Northeastern Colombian septic patient cohort. Further research is needed to clarify the correlation among sepsis, genetic factors with allele T and MMP-9 plasma concentration.

Absence of influence of polymorphisms of the MBL2 gene in oral infections by HSV-1 in individuals with HIV

Polymorphisms in the structural gene MBL-2 (mannose-binding lectin-2) may result in low MBL serum concentration, associated with greater susceptibility to infection. The study evaluated the effects of MBL-2 polymorphisms with the oral manifestations of the HSV in human immunodeficiency virus (HIV)-infected patients. An observational case-control study was carried out, with the sample comprising 64 HIV+ and 65 healthy individuals. The signs and symptoms of HSV oral infection were evaluated, and oral mucosa buccal smears were collected. Polymorphisms of the MBL-2 gene and HSV-1 DNA were amplified through real-time PCR. The data revealed that of 64 HIV+, 29.6% presented signs and symptoms of HSV oral infection. Of these, the HSV-1 DNA was detected through real-time PCR in 21% of cases, and in 13.3% of asymptomatic individuals. There was no statistically significant difference between the symptomatic (p = 1) and the asymptomatic (p = 0.52) individuals, HIV+ and HIV-. Different genotypes (AA, A0, or 00) did not contribute to the oral manifestation of HSV in the HIV+ patients (p = 0.81) or HIV- (p = 0.45). There was no statistically significant difference in either group (p = 0.52). No significant association was identified between the MBL-2 gene polymorphisms in the oral manifestation of HSV infection. However, further studies are recommended with larger population groups before discarding this interrelationship.

Association of a placental Interleukin-6 genetic variant (rs1800796) with DNA methylation, gene expression and risk of acute chorioamnionitis

BACKGROUND

Acute chorioamnionitis (aCA), inflammation of the placenta and fetal membranes, is a frequently reported lesion in preterm deliveries. Genetic variants in innate immune system genes such as Interleukin-6 (IL6) may contribute to the placenta's inflammatory response, thus predisposing some pregnancies to aCA. These genetic variants may modulate molecular processes such as DNA methylation and gene expression, and in turn might affect susceptibility to aCA. Currently, there is remarkably little research on the role of fetal (placental) genetic variation in aCA. We aimed to explore the associations between genetic variants in candidate immune-system genes and susceptibility towards inflammatory responses in the placenta, which is linked to a strong inflammatory response in the newborn.

METHODS

DNA samples from 269 placentas (72 aCA cases, 197 non-aCA cases) were collected for this study. Samples were genotyped at 55 ancestry informative markers (AIMs) and 16 additional single nucleotide polymorphisms (SNPs) in 12 candidate innate immune system genes using the Sequenom iPLEX Gold Assay. Publicly available datasets were used to obtain DNA methylation (GSE100197, GSE74738, GSE115508, GSE44667, GSE98224) and gene expression data (GSE44711, GSE98224).

RESULTS

Differences in IL6 placental allele frequencies were associated with aCA (rs1800796, p = 0.04) with the CC genotype specifically implicated (OR = 3.1; p = 0.02). In a subset of the placental samples (n = 67; chorionic villi), we showed that the IL6 SNP (rs1800796) was associated with differential DNA methylation in five IL6-related CpG sites (cg01770232, cg02335517, cg07998387, cg13104385, and cg0526589), where individuals with a CC genotype showed higher DNA methylation levels than individuals carrying the GG genotype. Using two publicly available datasets, we observed that the DNA methylation levels at cg01770232 negatively correlated with IL6 gene expression in the placenta (r = - 0.67, p < 0.004; r = - 0.56, p < 2.937e-05).

CONCLUSIONS

We demonstrated that the minor C allele at the IL6 SNP (rs1800796), which is largely limited to East Asian populations, is associated with the presence of aCA. This SNP was associated with increased DNA methylation at a nearby MEPC2 binding site, which was also associated with decreased expression of IL6 in the placenta. Decreased expression of IL6 may increase vulnerability to microbial infection. Additional studies are required to confirm this association in Asian populations with larger sample sizes.

Mannose-binding lectin genotypes and outcome in end-stage renal disease: a prospective cohort study

Background

Patients with end-stage renal disease (ESRD) have high morbidity and mortality rates, with cardiovascular diseases and infections being the major causes of death. Mannose-binding lectin (MBL) has been suggested to play a protective role in this regard. The aim of this study was to investigate a possible clinical association of MBL genotypes (MBL2) with outcome among patients on dialysis or with a functioning graft.

Methods

A total of 98 patients with ESRD accepted for living-donor renal transplantation or on the waiting list for transplantation were included and prospectively followed for an average of 9 years (range 7.5-9.9). Medical records were evaluated regarding transplantation status, diabetes mellitus, vascular parameters and infections for all the patients. Cox regression models and logistic regression analysis were used for statistical analyses. The cohort was divided into two groups according to the MBL2 genotype (normal A/A versus variant A/O or O/O).

Results

We found no evidence for an association between the MBL2 genotype and all-cause mortality, cardiovascular events or bacterial infections (pneumonia, urinary tract infection, fistula infection or other infections).

Conclusion

In this cohort, the MBL2 genotype did not seem to be associated with any long-term clinical effects in ESRD patients on dialysis or with a functioning graft.

Mannose-Binding Lectin 2 Gene Polymorphism in PANDAS Patients

Introduction

Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS), a subgroup of obsessive-compulsive disorder (OCD), has received much attention even though the specific underlying mechanisms remain unknown. Mannose-binding lectin (MBL) is a key factor in the innate immune response. The aim of this study was to investigate the role of MBL2 gene polymorphisms in pediatric OCD patients diagnosed as PANDAS, PANDAS-Variant and non-PANDAS.

Methods

The study included 102 pediatric OCD patients (59 [57.8% ] PANDAS, 20 [19.6% ] non-PANDAS, and 23 [22.5% ] PANDAS-Variant) and 60 healthy controls. Polymorphisms at codon 52, 54 and 57 of the MBL2 gene were investigated.

Results

Codon 54 polymorphism and any variant of MBL2 gene were significantly more frequent in the OCD group than in the control group (OR=2.97, 95% CI: 1.26-6.97; and OR=2.66, 95% CI: 1.32-5.38, respectively). According to regression analysis, the presence of any variant of MBL2 gene was found in 14.50-fold increased frequency in the PANDAS subgroup compared with the non-PANDAS subgroup (95% CI: 2.49-84.19).

Conclusions

Our findings support an association between MBL2 genotypes and pediatric OCD, particularly PANDAS-OCD.

Serial Changes in Mannose-Binding Lectin in Patients with Sepsis

Background

Mannose-binding lectin (MBL) deficiency leads to increased susceptibility to infection. We investigated whether serial changes in MBL levels are associated with the prognosis of patients diagnosed with septic shock, and correlated with cytokine levels.

Methods

We enrolled 131 patients with septic shock in the study. We analyzed the serum samples for MBL and cytokine levels at baseline and 7 days later. Samples on day 7 were available in 73 patients.

Results

We divided the patients with septic shock into four groups according to serum MBL levels (<1.3 µg/mL or ≥1.3 µg/mL) on days 1 and 7. Patients with low MBL levels on day 1 and high MBL levels on day 7 showed a favorable prognosis for 28-day survival (odds ratio, 1.96, 95% confidence interval, 1.10–2.87; p=0.087). The high MBL group on day 7 showed a significant decrease in monocyte chemoattractant protein 1, interleukin (IL)-1β, IL-6, IL-8, interferon-γ, and granulocyte macrophage colony-stimulating factor levels compared with the low MBL group on day 7.

Conclusion

The increase in MBL levels of patients with septic shock may suggest a favorable prognosis and attenuate pro-inflammatory and anti-inflammatory responses.

Familial aggregation of tonsillectomy in early childhood and adolescence

Background

The tonsils are immunological gatekeepers against pathogens. Immunological response to tonsillitis may vary clinically from no enlargement of the tonsils to nearly obstructive conditions. In this investigation, we studied the familial aggregation of tonsillectomy, as an indicator of the extent to which tonsillar immune responses to infections might be genetically controlled.

Methods

Data on kinship relations and vital status from the Danish Civil Registration System were used to establish a cohort of Danes with relatives born since 1977. Tonsillectomies in all hospitals and clinics from 1977 to 2013 were identified in national registers together with the indication for tonsillectomy. Rate ratios (RRs) for tonsillectomy >1 year after tonsillectomy in specific types of relatives (first to fourth degree) were estimated in Poisson regression models with adjustment for calendar period, sex, age, and total number of specified relatives.

Results

A cohort of 2.4 million persons was followed for 44,100,697 million person-years (mean 18.4 years/person), and included 148,190 tonsillectomies. RRs of tonsillectomy were consistently higher when the relatedness and the number of tonsillectomized relatives were higher. RRs were similar in boys and girls, but were larger in early childhood. Additional analyses suggested that this relatively higher RR at younger ages was due to a larger influence of shared environment at younger ages, whereas the genetic influence was similar at all ages. Results were similar for tonsillectomies performed strictly due to tonsillitis.

Conclusions

Genetic factors appear to predispose to severe tonsillitis underlying tonsillectomies, regardless of age and sex. Further studies are needed to understand how genes regulate the tonsils' immune response against infections.

Mannose-Binding Lectin Levels Could Predict Prognosis in IgA Nephropathy

IgA nephropathy (IgAN) is characterized by infections followed by episodic gross hematuria. Deficiency of mannose-binding lectin (MBL) is associated with recurrent infection in many diseases, but controversy exists regarding the role of MBL in IgAN. Here, we measured MBL2 variants and MBL levels in 749 patients with IgAN and 489 healthy controls. Overall, 5.2% (39 of 749) of patients with IgAN had MBL deficiency (MBL levels <100 ng/ml), among whom LYPB/LYPB and LXPA/LYPB were the predominant MBL2 haplotypes (82%; 32 of 39). We found a nonlinear association between MBL levels and renal outcome in IgAN. Patients with IgAN and MBL deficiency had a higher incidence of prodromic infections and gross hematuria than those with sufficient MBL levels (100-3540 ng/ml). Moreover, MBL deficiency independently associated with poor renal outcome in IgAN after multiple adjustments (hazard ratio, 5.18; 95% confidence interval, 2.50 to 10.72; P<0.001). Patients with high MBL levels (>3540 ng/ml) had more severe proteinuria and a higher proportion of crescents, although the association with IgAN progression did not reach statistical significance after adjustments. In conclusion, MBL deficiency and MBL excess may both have deleterious effects on IgAN progression, which suggests that MBL contributes to IgAN pathogenesis through multiple mechanisms.

Recurrent respiratory tract infections (RRTI) in the elderly: A late onset mild immunodeficiency?

Elderly with late-onset recurrent respiratory tract infections (RRTI) often have specific anti-polysaccharide antibody deficiency (SPAD). We hypothesized that late-onset RRTI is caused by mild immunodeficiencies, such as SPAD, that remain hidden through adult life. We analyzed seventeen elderly RRTI patients and matched controls. We determined lymphocyte subsets, expression of BAFF receptors, serum immunoglobulins, complement pathways, Pneumovax-23 vaccination response and genetic variations in BAFFR and MBL2. Twelve patients (71%) and ten controls (59%) had SPAD. IgA was lower in patients than in controls, but other parameters did not differ. However, a high percentage of both patients (53%) and controls (65%) were MBL deficient, much more than in the general population. Often, MBL2 secretor genotypes did not match functional deficiency, suggesting that functional MBL deficiency can be an acquired condition. In conclusion, we found SPAD and MBL deficiency in many elderly, and conjecture that at least the latter arises with age.

Polymorphisms of Mannose-binding Lectin and Toll-like Receptors 2, 3, 4, 7 and 8 and the Risk of Respiratory Infections and Acute Otitis Media in Children

BACKGROUND

Mannose-binding lectin (MBL) and toll-like receptors (TLRs) are important components of the innate immune system. We assessed the susceptibility of children with genetic variants in these factors to respiratory infections, rhinovirus infections and acute otitis media.

METHODS

In a prospective cohort study, blood samples from 381 Finnish children were analyzed for polymorphisms in MBL2 at codons 52, 54 and 57, TLR2 Arg753Gln, TLR3 Leu412Phe, TLR4 Asp299Gly, TLR7 Gln11Leu and TLR8 Leu651Leu. Children were followed up for respiratory infections until 24 months of age with daily diaries. Polymerase chain reaction and antigen tests were used for detection of respiratory viruses from nasal swabs.

RESULTS

Children with MBL variant genotype had a mean of 59 days with symptoms of respiratory infection per year, compared with 49 days in those with wild-type (P = 0.01). TLR8 polymorphisms were associated with an increased risk and TLR7 polymorphisms with a decreased risk of recurrent rhinovirus infections (P = 0.02 for both). TLR2 polymorphisms were associated with recurrent acute otitis media (P = 0.02). MBL polymorphisms were associated with an increased and TLR7 polymorphisms with a decreased risk of rhinovirus-associated acute otitis media (P = 0.03 and P = 0.006, respectively).

CONCLUSIONS

Genetic polymorphisms in MBL and TLRs promote susceptibility to or protection against respiratory infections. In addition to environmental factors, genetic variations may explain why some children are more prone to respiratory infections.

Evaluation of Mannose-Binding Lectin is a Useful Approach to Predict the Risk of Infectious Complications Following Autologous Hematopoietic Stem Cell Transplantation

Hematopoietic stem cell transplantation (HSCT) associated immunocompromised state carries high risk of infectious complications. Mannose-binding lectin (MBL) is an acute phase protein involved in innate immune response. Serum MBL level is genetically determined and quite stable. According to literature, significant association was shown between low MBL concentrations and serious infections. The association between serum MBL level and frequency and severity of infections was studied in 186 patients following autologous HSCT. Double-monoclonal antibody sandwich enzyme-linked immunosorbent assay was used to determine MBL antigen level in sera. MBL levels were measured around 100 days following transplantation, in a period without active infection. Twenty-one patients (11%) were MBL deficient. The median time of first infection and number of infections during the first year post-transplantation were not significantly different between patients with MBL deficiency and those without MBL deficiency. The occurrence and number of infections after HSCT correlated with the MBL/C-reactive protein ratio. The number of severe infections was not higher among those with MBL deficiency. The occurrence of infections after the pre-engraftment period during the first year post-transplantation was significantly different in patient groups separated by MBL cut-off level. The MBL/C-reactive protein ratio might be a useful marker of infectious complications. MBL measurement may be helpful in antibiotic treatment. In case of MBL deficiency, earlier and more intensive treatment may be indicated.

High rate of in-stent restenosis after coronary intervention in carriers of the mutant mannose-binding lectin allele

Background

In-stent restenosis occurs in 10–30% of patients following bare metal stent (BMS) implantation and has various risk factors. Mannose-binding lectin (MBL) is known to have effect on the progression of atherosclerosis. Single nucleotide polymorphisms (SNP) of the MBL2 gene intron 1 (codon 52, 54, 57) are known to modulate the bioavailability of the MBL protein. Our aim was to identify the association of these polymorphisms of the MBL gene in the occurrence of in-stent restenosis after coronary artery bare metal stent implantation.

Methods

In a non-randomized prospective study venous blood samples were collected after recoronarography from 225 patients with prior BMS implantation. Patients were assigned to diffuse restenosis group and control group based on the result of the coronarography. MBL genotypes were determined using quantitative real-time PCR. Proportion of different genotypes was compared and adjusted with traditional risk factors using multivariate logistic regression.

Results

Average follow-up time was 1.0 (+ − 1.4) year in the diffuse restenosis group (N = 117) and 2.7 (+ − 2.5) years in the control group (N = 108). The age, gender distribution and risk status was not different between study groups. Proportion of the MBL variant genotype was 26.8% (29 vs. 79 normal homozygous) in the control group and 39.3% (46 vs. 71 normal homozygous) in the restenosis group (p = 0.04). In multivariate analysis the mutant allele was an independent risk factor (OR = 1.96, p = 0.03) of in-stent restenosis.

Conclusions

MBL polymorphisms are associated with higher incidence of development of coronary in-stent restenosis. The attenuated protein function in the mutant allelic genotype may represent the underlying mechanism.

Burden of Recurrent Respiratory Tract Infections in Children: A Prospective Cohort Study

BACKGROUND

The burden of recurrent respiratory infections is unclear. We identified young children with recurrent respiratory infections in order to characterize the clinical manifestations, risk factors and short-term consequences.

METHODS

In this prospective cohort study, 1089 children were followed from birth to 2 years of age for respiratory infections by a daily symptom diary. Nasal swabs taken during respiratory infections were analyzed for viruses from 714 children. Nasopharyngeal swabs collected at 2 months of age were cultured for bacteria. The 10% of children with the highest number of annual respiratory illness days were defined to have recurrent respiratory tract infections.

RESULTS

The 90th percentile in the number of annual respiratory illness days was 98. Children above this limit (n = 109) had a median of 9.6 acute respiratory infections per year. Rhinovirus was detected in 58% of their infections. Of the children with recurrent infections, 60% were diagnosed with at least 3 episodes of acute otitis media, 73% received at least 3 antibiotic treatments and 21% were hospitalized for an acute respiratory infection. Tympanostomy was performed for 35% and adenoidectomy for 13% of the children. Asthma was diagnosed in 12% by 24 months of age. Older siblings increased the risk of recurrent respiratory infections. Early nasopharyngeal colonization with Streptococcus pneumoniae was common in children who later developed recurrent infections.

CONCLUSIONS

Children with recurrent respiratory infections frequently use health care services and antibiotics, undergo surgical procedures and are at risk for asthma in early life. Having older siblings increases the risk of recurrent infections.

Association between TLR2/TLR4 gene polymorphisms and COPD phenotype in a Greek cohort

BACKGROUND

Considering that the innate immune system plays a pivotal role in the pathogenesis of chronic obstructive pulmonary disease (COPD), we hypothesized that functional single-nucleotide polymorphisms (SNPs) of innate immune genes affect the disease phenotype and prognosis.

AIM

To elucidate the contribution of common functional TLR2 and TLR4 SNPs and genotypic deficiency of the mannose-binding lectin (MBL) protein, both as single parameters and in combination, in Greek COPD patients.

RESULTS

In a cohort of 114 Greek COPD patients, we confirmed that the presence of TLR4-D299G or TLR4-T399I SNPs was significantly associated with an earlier COPD stage (p = 0.003 and p = 0.009, respectively). In comparison, the absence of any analyzed polymorphism, including those of TLR2-R753Q and genotypic MBL deficiency, was significantly associated with a more severe disease phenotype, characterized by more frequent exacerbations (p = 0.045).

CONCLUSION

Our findings support the notion that the presence of innate immune SNPs, such as functional polymorphisms of TLRs along with MBL deficiency, might exert a protective effect on the COPD phenotype, similar with other immune-mediated disorders.

Pediatric chronic rhinosinusitis

The goal of this review is to elucidate the pathogenic factors, histopathologic features, and special considerations that relate to pediatric versus adult chronic rhinosinusitis (CRS) and to emphasize differences and similarities between the adult and pediatric conditions. Emphasis is placed on understanding of the differences in pathogenic mechanisms, host-microbial interactions, potential defects in innate antimicrobial immunity, and the role of biofilm formation in pediatric versus adult CRS and how these translate to different approaches toward both medical and surgical management. Pediatric CRS can be viewed as evolving from acute bacterial rhinosinusitis into an uncomplicated "early" stage of CRS, later evolving into a persistent stage and, in some cases, evolving into a late "maladaptive-eosinophilic" stage disease. Given this potential evolution toward more irreversible disease, a plea can be made for improved recognition of and more aggressive early intervention for pediatric CRS, it is hoped, to prevent these long-term consequences. For the primary care physician, this may necessitate enlisting the support of a sinus specialist before the symptoms of CRS have persisted for months or years. It may also necessitate, in some cases, the use of sinus computed tomography imaging to demonstrate that sinus abnormalities have resolved. Other arguments can be made for prompt and comprehensive management of pediatric CRS, including the need to reduce the burden of illness, reduce health care costs, avoid unnecessary antibiotic use and its attendant effects toward promoting antibiotic resistant infections and, potentially, to reduce the development of important comorbidities, e.g., asthma.

MBL2 polymorphisms and the risk of asthma: A meta-analysis

BACKGROUND

The association between MBL2 gene polymorphisms and the risk of asthma has been evaluated in multiple studies; however, the results are inconsistent.

OBJECTIVE

To perform a meta-analysis to explore whether MBL2 gene polymorphisms were associated with the risk of asthma.

METHODS

We searched PubMed, Web of Science, and Cochrane Library to find relevant articles published up to March 2016. Nine studies, including 2066 cases and 2183 controls, were included in the meta-analysis. The strength of association was evaluated by odds ratio (OR) with 95% confidence interval (CI).

RESULTS

The results reveal that MBL2 gene polymorphisms (codon 54 A/B, -550 H/L or -221 X/Y) were not associated with the risk of asthma (codon 54 A/B: BB+AB vs AA: OR, 1.02; 95% CI, 0.85-1.23; -550 H/L: LL+HL vs HH: OR, 0.81; 95% CI, 0.63-1.03; -221 X/Y: XX+YX vs YY: OR, 0.85; 95% CI, 0.69-1.04). Subgroup analysis by ethnicity implied that the MBL2 codon 54 A/B polymorphism was not significantly associated with the risk of asthma in Asians (BB+AB vs AA: OR, 0.95; 95% CI, 0.70-1.29) or whites (BB+AB vs AA: OR, 1.07; 95% CI, 0.84-1.35).

CONCLUSION

The results indicated that MBL2 gene polymorphisms (codon 54 A/B, -550 H/L or -221 X/Y) may be not associated with the risk of asthma.

Overview of Infections in the Immunocompromised Host

Understanding the components of the immune system that contribute to host defense against infection is key to recognizing infections that are more likely to occur in an immunocompromised patient. In this review, we discuss the integrated system of physical barriers and of innate and adaptive immunity that contributes to host defense. Specific defects in the components of this system that predispose to particular infections are presented. This is followed by a review of primary immunodeficiency diseases and secondary immunodeficiencies, the latter of which develop because of a specific illness or condition or are treatment-related. The effects of treatment for neoplasia, autoimmune diseases, solid organ and stem cell transplants on host defenses are reviewed and associated with susceptibility to particular infections. In conclusion, an approach to laboratory screening for a suspected immunodeficiency is presented. Knowledge of which host defects predispose to specific infections allows clinicians to prevent, diagnose, and manage infections in their immunocompromised patients most effectively.

Antibodies to mannose binding lectin in patients with systemic lupus erythematosus

Deficiency of mannose binding lectin (MBL), a C-type lectin with structural similarities to C1q, has been shown to predispose to the development of systemic lupus erythematosus (SLE). Some patients have low serum MBL levels which cannot be explained by either structural gene mutations or promoter polymorphisms. The objective of this study was to detect the presence of autoantibodies against MBL and to evaluate their relationship to serum MBL levels. Anti-MBL antibodies of IgM and IgG classes from consecutive SLE patients (n 1/4 135) and healthy subjects (n 1/4 50) were measured by an in-house ELISA. Using the 90th percentile of controls as a cutoff, more SLE patients [23.7% (32/135)] were found to have IgG anti-MBL antibodies than normal controls [10.0% (5/50)] (P 1/4 0.04). The same trend was observed when ethnicity was taken into account by analysing Caucasians alone (n 1/4 90). IgM anti-MBL antibodies were only found in two SLE patients (2/22, 9.1%) who had no concomitant IgG anti-MBL antibodies. Serum levels of IgG anti-MBL antibodies were found to correlate with serum MBL levels (r 1/4 0.55, P 1/4 0.049). However, the levels of anti-MBL antibodies did not correlate with overall disease activity. Thus the production of anti-MBL antibodies is likely to be a specific antigen-driven process. Its role in lupus pathogenesis remains to be elucidated.

The staphylococcal surface-glycopolymer wall teichoic acid (WTA) is crucial for complement activation and immunological defense against Staphylococcus aureus infection

Staphylococcus aureus is a Gram-positive bacterial pathogen that is decorated by glycopolymers, including wall teichoic acid (WTA), peptidoglycan, lipoteichoic acid, and capsular polysaccharides. These bacterial surface glycopolymers are recognized by serum antibodies and a variety of pattern recognition molecules, including mannose-binding lectin (MBL). Recently, we demonstrated that human serum MBL senses staphylococcal WTA. Whereas MBL in infants who have not yet fully developed adaptive immunity binds to S. aureus WTA and activates complement serum, MBL in adults who have fully developed adaptive immunity cannot bind to WTA because of an inhibitory effect of serum anti-WTA IgG. Furthermore, we showed that human anti-WTA IgGs purified from pooled adult serum IgGs triggered activation of classical complement-dependent opsonophagocytosis against S. aureus. Because the epitopes of WTA that are recognized by anti-WTA IgG and MBL have not been determined, we constructed several S. aureus mutants with altered WTA glycosylation. Our intensive biochemical studies provide evidence that the β-GlcNAc residues of WTA are required for the induction of anti-WTA IgG-mediated opsonophagocytosis and that both β- and α-GlcNAc residues are required for MBL-mediated complement activation. The molecular interactions of other S. aureus cell wall components and host recognition proteins are also discussed. In summary, in this review, we discuss the biological importance of S. aureus cell surface glycopolymers in complement activation and host defense responses.

Phospholipase A2 Receptor-Related Membranous Nephropathy and Mannan-Binding Lectin Deficiency

Most patients with idiopathic membranous nephropathy (IMN) have IgG4 autoantibodies against phospholipase A2 receptor (PLA2R). C3 and C5b-9 are found in immune deposits of IMN kidney biopsy specimens, but the pathway of complement activation in IMN remains elusive. We report the case of a patient who developed IMN with intense staining for PLA2R, IgG4, C3, C5b-9, factor B, and properdin and very weak staining for C1q, C4d, and IgG1. Measurement of mannan binding lectin (MBL) antigenic level and activity revealed MBL deficiency. Genotyping revealed a heterozygous (A/C) polymorphism in codon 57 of MBL2 exon 1 associated with homozygous and heterozygous variations in the promoter region at -550 (L/L) and -221 (X/Y), respectively, suggesting that the patient harbored the LXA/LYC haplotypes linked to MBL deficiency. Genetic sequencing in 77 consecutive patients with IMN identified four patients with MBL2 promoter and coding region variations associated with MBL deficiency and the same complement pattern in immune deposits as the index patient. In contrast, patients with wild-type MBL2 had immune deposits with intense Cd4 staining. Thus, IMN can develop in patients with complete MBL deficiency, with complement activated mainly by the alternative pathway, whereas the lectin pathway is also activated in those with wild-type MBL2.

Susceptibility to Lower Respiratory Infections in Childhood is Associated with Perturbation of the Cytokine Response to Pathogenic Airway Bacteria

BACKGROUND

Neonatal colonization of the airways with respiratory pathogens is associated with increased risk of lower respiratory infections (LRI) in early childhood. Therefore, we hypothesized that children developing LRI have an aberrant immune response to pathogenic bacteria in infancy. The objective was to characterize in vitro the early life systemic immune response to pathogenic bacteria and study the possible association with incidence of LRI during the first 3 years of life.

METHODS

The Copenhagen Prospective Studies on Asthma in Childhood2000 (COPSAC2000) is a clinical birth cohort study of 411 children born of mothers with asthma. LRI incidence was prospectively captured from 6-monthly planned visits and visits at acute respiratory episodes. The in vitro systemic immune response to Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pneumoniae was characterized by the production of TNF-α, IFN-γ, IL-2, IL-5, IL-10, IL-13 and IL-17 in peripheral blood mononuclear cells isolated at age 6 months from 291 infants. Data were analyzed by Poisson regression against incidence of LRI in infancy.

RESULTS

A multivariable model including all cytokine responses from the 3 different bacterial stimulations significantly identified children at risk of LRI (P = 0.006). The immune response pattern associated with LRI was characterized by perturbed production of several cytokines rather than production of one specific cytokine, and was independent of concurrent asthma. TNF-α and IL-5 were key drivers but did not explain the entire variation in LRI susceptibility.

CONCLUSIONS

Children at risk of future LRI present a perturbed systemic immune response upon exposure to common airway pathogens in early life.