Association of CD14 promoter polymorphism with otitis media and pneumococcal vaccine responses

The ECRG4 cleavage product augurin binds the endotoxin receptor and influences the innate immune response during otitis media

Otitis media (OM), the most common disease of childhood, is typically characterized by bacterial infection of the middle ear (ME). Prominent features of OM include hyperplasia of the ME mucosa, which transforms from a monolayer of simple squamous epithelium with minimal stroma into a full-thickness respiratory epithelium in 2-3 days after infection. Analysis of the murine ME transcriptome during OM showed down-regulation of the tumor suppressor gene Ecrg4 that was temporally related to mucosal hyperplasia and identified stromal cells as the primary ECRG4 source. The reduction in Ecrg4 gene expression coincided with the cleavage of ECRG4 protein to release an extracellular fragment, augurin. The duration of mucosal hyperplasia during OM was greater in Ecrg4 ^-/- mice, the number of infiltrating macrophages was enhanced, and ME infection cleared more rapidly. ECRG4-null macrophages showed increased bacterial phagocytosis. Co-immunoprecipitation identified an association of augurin with TLR4, CD14 and MD2, the components of the lipopolysaccharide (LPS) receptor. The results suggest that full-length ECRG4 is a sentinel molecule that potentially inhibits growth of the ME stroma. Processing of ECRG4 protein during inflammation, coupled with a decline in Ecrg4 gene expression, also influences the behavior of cells that do not express the gene, limiting the production of growth factors by epithelial and endothelial cells, as well as the activity of macrophages.

Essential Role of the Innate Immune Adaptor RIP2 in the Response to Otitis Media

Intracellular nucleotide binding and oligomerization domain (NOD) and Toll-like (TLR) receptors have emerged as pivotal sensors of infection. Both Nod1 and Nod2 contain a caspase activation and recruitment domain (CARD) that interacts with the adaptor protein RIP2 (receptor-interaction protein-2). This leads to ubiquitination of RIP2 and in turn to the activation of NFκB and MAPK transcription factors, to command the host defensive response against pathogenic infections. RIP2 is also activated by TLRs 2 and 4, although the mechanism of this activation is less. The role of RIP2 in otitis media (OM) pathogenesis has yet to be examined. Herein, we used in vivo animal models including C57BL/6 wild-type (WT) and RIP2-/- knockout mice inoculated in the middle ear (ME) with non-typeable Haemophilus influenzae (NTHi), a common human OM pathogen, to evaluate the expression of RIP2 and its signaling genes at the cellular level to determine the role of RIP2 in OM pathogenesis and recovery. The Nod1, Nod2, and Ripk2 genes are minimally expressed in the normal ME. However, they are strongly upregulated during acute OM, as are many genes related to RIP2 signaling. However, while signaling genes were expressed by various ME cell types, only mucosal epithelial and stromal cells expressed the NODs, RIP2, and signaling genes required for the activation of the host defensive response. Whereas WT mice clear ME bacteria and recover from OM within 5 days after infection, RIP2-deficient mice show persistent ME bacterial carriage and inflammation to at least 15 days. This includes significantly prolonged mucosal hyperplasia and ME leukocytic infiltration. Recruitment of macrophages is also delayed in comparison to WT mice. Thus, RIP2 is required to elicit a robust innate immune response that promotes bacterial clearance and increases host innate resistance. The results also identify the structural cells of the ME mucosa, as opposed to leukocytes, as the primary sites of NOD/RIP2 activity in the infected ME.

Genomics of Otitis Media (OM): Molecular Genetics Approaches to Characterize Disease Pathophysiology

Otitis media (OM) is an infective and inflammatory disorder known to be a major cause of hearing impairment across all age groups. Both acute and chronic OM result in substantial healthcare utilization related to antibiotic prescription and surgical procedures necessary for its management. Although several studies provided evidence of genetics playing a significant role in the susceptibility to OM, we had limited knowledge about the genes associated with OM until recently. Here we have summarized the known genetic factors that confer susceptibility to various forms of OM in mice and in humans and their genetic load, along with associated cellular signaling pathways. Spotlighted in this review are fucosyltransferase (FUT) enzymes, which have been implicated in the pathogenesis of OM. A comprehensive understanding of the functions of OM-associated genes may provide potential opportunities for its diagnosis and treatment.

NOD1/NOD2-mediated recognition of non-typeable Haemophilus influenzae activates innate immunity during otitis media

Pathogen recognition following infection in mammals depends mainly on TLRs and NLRs. Herein, we evaluate the role of NOD1 and NOD2 signaling in the inflammatory responses of the middle ear (ME) mucosa and leukocytes recruitment to infection site during otitis media (OM). OM is a common pediatric disease with prevalent repercussions on hearing health. While many risk factors have been implicated to OM proneness, immunity and the triggering of inflammation are central to OM pathology. We observed that many genes encoding members of the NOD leucine-rich repeat and their downstream adaptor/effector molecules were strongly regulated during the course of OM. When compared to wild type C57BL/6 mice, NOD1- and NOD2-deficient mice were susceptible to prolonged OM infection by non-typeable Haemophilus influenza. NOD1-deficient mice appeared to have reduced macrophage enlistment with a delayed inflammatory response by neutrophils and prolonged mucosal hyperplasia, whereas NOD2 knockouts exhibited an overall reduction in the number of leukocytes recruited to the ME, leading to delayed bacterial clearance. Altogether, these data show that the NODs play a role in the pathogenesis and recovery of OM and reinforce the importance of innate immune signaling in the protective host response.

Genome-wide association analysis reveals variants on chromosome 19 that contribute to childhood risk of chronic otitis media with effusion

To identify genetic risk factors of childhood otitis media (OM), a genome-wide association study was performed on Finnish subjects, 829 affected children, and 2118 randomly selected controls. The most significant and validated finding was an association with an 80 kb region on chromosome 19. It includes the variants rs16974263 (P = 1.77 × 10(-7), OR = 1.59), rs268662 (P = 1.564 × 10(-6), OR = 1.54), and rs4150992 (P = 3.37 × 10(-6), OR = 1.52), and harbors the genes PLD3, SERTAD1, SERTAD3, HIPK4, PRX, and BLVRB, all in strong linkage disequilibrium. In a sub-phenotype analysis of the 512 patients with chronic otitis media with effusion, one marker reached genome-wide significance (rs16974263, P = 2.92 × 10(-8)). The association to this locus was confirmed but with an association signal in the opposite direction, in a UK family cohort of 4860 subjects (rs16974263, P = 3.21 × 10(-4), OR = 0.72; rs4150992, P = 1.62 × 10(-4), OR = 0.71). Thus we hypothesize that this region is important for COME risk in both the Finnish and UK populations, although the precise risk variants or haplotype background remain unclear. Our study suggests that the identified region on chromosome 19 includes a novel and previously uncharacterized risk locus for OM.

Association of cytokine gene polymorphisms and risk factors with otitis media proneness in children

In order to assess the association between gene polymorphisms and otitis media (OM) proneness, tumor necrosis factor alpha (TNFA) -308, interleukin (IL) 10-1082 and -3575, IL6 -597, IL2 -330, and CD14 -159 genotyping was performed in 58 OM-prone children and 85 controls who were exposed to similar number and frequency of environmental and host risk factors. The frequencies of genotypes (wild type vs. genotypes containing at least one polymorphic allele) were not significantly different between groups, except for IL10 -1082. Polymorphic genotypes IL10 -1082 GA and GG were more frequent in OM-prone children than in control group (RR 1.145, 95 % CI 1.011-1.298; p = 0.047). However, logistic regression did not confirm IL10 -1082 polymorphic genotypes as an independent risk factor for OM proneness.

CONCLUSION

The present study indicates that high-producing IL10 -1082 GA/GG genotypes may increase the risk for OM proneness in its carriers when exposed to other environmental/host risk factors (day care attendance, passive smoking, male sex, respiratory infections, and atopic manifestations). This study revealed no significant independent genetic association, but the lack of breastfeeding in infancy was found to be the only independent risk factor for development of OM-prone phenotype, implying that breastfeeding had a protective role in development of susceptibility to OM.

WHAT IS KNOWN

• The pathogenesis of OM is of multifactorial nature, dependent on infection, environmental factors, and immune response of the child. • Cytokines and CD14 play an important role in the presentation and clinical course of otitis media, but a clear link with otitis media proneness was not established. What is new: • This is the first clinical and genetic study on Montenegrin children with the otitis media-prone phenotype. • The study revealed that high-producing IL10 -1082 genotypes may influence otitis media proneness in children exposed to other environmental/host risk factors.

Differences of plasma IL-1 and TNF-α in healthy Chinese Population

Pleiotropic proinflammatory cytokines, interleukin- 1 (IL-1) and tumor necrosis factor-α (TNF-α), involved in the regulations of various immune responses, inflammatory processes and hematopoiesis. In the present study, the expression levels of IL-1 and TNF-α were detected by enzyme-linked immunosorbent assay (ELISA). Following the cytokine blockade as a successful clinical therapy for autoimmune diseases such as rheumatoid arthritis, the patients are more susceptible to a variety of opportunistic infections. IL-1 and TNF-α may be useful predictive biomarkers of diseases and offer potential targets for therapeutic intervention of inflammatory diseases. However, our results showed that the plasma IL-1 level was significantly higher in women compared to men (69.5 ± 19.8 pg/ml in men and 80.1 ± 19.5 pg/ml in women, respectively); the plasma levels of TNF-α were higher in men than women (20.8 ± 4.9 pg/ml and 18.7 ± 7.1 pg/ml, respectively). The significant gender difference of plasma interleukin-1 (IL-1) and TNF-α levels present in healthy adults in Jiangsu Province, China (P=0.002 and P=0.015, respectively), and may be as a hint for sex differences of susceptibility to many diseases and elementary immune response.

NOD-Like Receptor Signaling in Cholesteatoma

Background. Cholesteatoma is a destructive process of the middle ear resulting in erosion of the surrounding bony structures with consequent hearing loss, vestibular dysfunction, facial paralysis, or intracranial complications. The etiopathogenesis of cholesteatoma is controversial but is associated with recurrent ear infections. The role of intracellular innate immune receptors, the NOD-like receptors, and their associated signaling networks was investigated in cholesteatoma, since mutations in NOD-like receptor-related genes have been implicated in other chronic inflammatory disorders. Results. The expression of NOD2 mRNA and protein was significantly induced in cholesteatoma compared to the external auditory canal skin, mainly located in the epithelial layer of cholesteatoma. Microarray analysis showed significant upregulation for NOD2, not for NOD1, TLR2, or TLR4 in cholesteatoma. Moreover, regulation of genes in an interaction network of the NOD-adaptor molecule RIPK2 was detected. In addition to NOD2, NLRC4, and PYCARD, the downstream molecules IRAK1 and antiapoptotic regulator CFLAR showed significant upregulation, whereas SMAD3, a proapoptotic inducer, was significantly downregulated. Finally, altered regulation of inflammatory target genes of NOD signaling was detected. Conclusions. These results indicate that the interaction of innate immune signaling mediated by NLRs and their downstream target molecules is involved in the etiopathogenesis and growth of cholesteatoma.

Immunity genes and susceptibility to otitis media: a comprehensive review

Otitis media (OM) is a middle ear infection associated with inflammation and pain. This disease frequently afflicts humans and is the major cause of hearing loss worldwide. OM continues to be one of the most challenging diseases in the medical field due to its diverse host targets and wide range of clinical manifestations. Substantial morbidity associated with OM is further exacerbated by high frequency of recurrent infections leading to chronic suppurative otitis media (CSOM). Children have greater susceptibility to, and thus, suffer most frequently from OM, which can cause significant deterioration in quality of life. Genetic factors have been demonstrated, in large part by twin and family studies, to be key determinants of OM susceptibility. In this review, we summarize the current knowledge on immunity genes and selected variants that have been associated with predisposition to OM. In particular, polymorphisms in innate immunity and cytokine genes have been strongly linked with the risk of developing OM. Future studies employing state-of-the-art technologies, including next-generation sequencing (NGS), will aid in the identification of novel genes associated with susceptibility to OM. This, in turn, will open up avenues for identifying high-risk individuals and designing novel therapeutic strategies based on precise targeting of these genes.

The effect of perinatal anxiety on bronchiolitis is influenced by polymorphisms in ROS-related genes

Background

Exposure to perinatal anxiety affects disease susceptibility in offspring but studies on the association between perinatal anxiety and gene polymorphisms are lacking. This study aimed to elucidate the interaction between perinatal anxiety and polymorphisms in antioxidant defense and innate immunity genes on the development of respiratory tract infections (RTIs) during early infancy.

Methods

Trait anxiety levels in 440 women were assessed by the State-Trait Anxiety Inventory during late gestation. The occurrence of RTIs, including bronchiolitis, during the first year of life was assessed by parent-reported doctor diagnosis. Polymorphisms in glutathione S-transferase P-1 (GSTP1, rs1695) and CD14 (rs2569190) were genotyped using the TaqMan assay. Copy number variations of GSTT1 were measured by real-time polymerase chain reaction.

Results

Exposure to high levels of perinatal anxiety increased the risk of bronchiolitis in the first year of life (adjusted odds ratio [aOR], 1.30; 95% confidence interval [CI]: 1.00–1.80), in particular among children with the AG + GG genotype of GSTP1 or the GSTT1 null genotype (aOR 3.36 and 2.79). In infants with the TC + CC genotype of CD14, high levels of perinatal anxiety were associated with an increased risk of upper RTI, lower RTI, and bronchiolitis (aOR 2.51, 4.60, and 4.31, respectively).

Conclusions

Perinatal maternal anxiety levels affect the occurrence of bronchiolitis in offspring. The effect of perinatal anxiety on the occurrence of bronchiolitis during infancy was influenced by genetic polymorphisms in antioxidant defense and innate immunity genes.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2466-14-154) contains supplementary material, which is available to authorized users.

Polymorphisms of immunity genes and susceptibility to otitis media in children

BACKGROUND

Acute otitis media (OM) is a common disease which often develops through complex interactions between the host, the pathogen and environmental factors. We studied single nucleotide polymorphisms (SNPs) of genes involved in innate and adaptive immunity, and other host and environmental factors for their role in OM.

METHODS

Using Sequenom Massarray platform, 21 SNPs were studied in 653 children from prospective (n = 202) and retrospective (n = 451) cohorts. Data were analyzed for the relationship between SNPs and upper respiratory infection (URI) frequency, risk of acute OM during URI episodes, and proneness to recurrent OM.

RESULTS

Increased risk for OM proneness was associated with CX3CR1 (Thr280Met) SNP and with a jointly interactive group of IL-10 (-1082) SNP, IL-1β (-511) wild type genotype and white race. Family history of OM proneness independently increased the risk for frequent URIs, OM occurrence during URI, and OM proneness. Additionally, IL-1β (-31) SNP was associated with increased risk for frequent URIs, but IL-10 (-592), IL-1β (-511), IL-5 (-746) and IL-8 (-251) SNPs were associated with decreased risk of URI.

CONCLUSION

IL-1β (-31), CX3CR1 (Thr280Met), IL-10 (-1082) and IL-1β (-511) SNPs were associated with increased risk for frequent URIs or OM proneness.

Current knowledge of the genetics of otitis media

Otitis media is one of the most common childhood infections leading to doctor's visits and a leading cause of antibiotic prescriptions in children. Twin and family studies have confirmed that the predisposition of developing a bacterial middle ear infection is genetically determined. Several case-control studies have been performed to analyze genes involved in inflammatory processes in search of potential associations. Modern genome-wide association approaches that require no prior assumptions of the involvement of a given gene locus in the risk of otitis media are currently being used to identify otitis media genes, and will hopefully give more detailed information on the pathogenesis of childhood otitis media. That information could be used in finding the high-risk patient, in the prevention of the disease, and in the design of new treatments.

The facial evolution: looking backward and moving forward

Three-dimensional (3D) facial analysis is ideal for high-resolution, nonionizing, noninvasive objective, high-throughput phenotypic, and phenomic studies. It is a natural complement to (epi)genetic technologies to facilitate advances in the understanding of rare and common diseases. The face is uniquely reflective of the primordial tissues, and there is evidence supporting the application of 3D facial analysis to the investigation of variation and disease including studies showing that the face can reflect systemic health, provides diagnostic clues to disorders, and that facial variation reflects biological pathways. In addition, facial variation has been related to evolutionary factors. The purpose of this review is to look backward to suggest that knowledge of human evolution supports, and may instruct, the application and interpretation of studies of facial morphology for documentation of human variation and investigation of its relationships with health and disease. Furthermore, in the context of advances of deep phenotyping and data integration, to look forward to suggest approaches to scalable implementation of facial analysis, and to suggest avenues for future research and clinical application of this technology.

Exome sequencing identifies a missense mutation in Isl1 associated with low penetrance otitis media in dearisch mice

Background

Inflammation of the middle ear (otitis media) is very common and can lead to serious complications if not resolved. Genetic studies suggest an inherited component, but few of the genes that contribute to this condition are known. Mouse mutants have contributed significantly to the identification of genes predisposing to otitis media

Results

The dearisch mouse mutant is an ENU-induced mutant detected by its impaired Preyer reflex (ear flick in response to sound). Auditory brainstem responses revealed raised thresholds from as early as three weeks old. Pedigree analysis suggested a dominant but partially penetrant mode of inheritance. The middle ear of dearisch mutants shows a thickened mucosa and cellular effusion suggesting chronic otitis media with effusion with superimposed acute infection. The inner ear, including the sensory hair cells, appears normal. Due to the low penetrance of the phenotype, normal backcross mapping of the mutation was not possible. Exome sequencing was therefore employed to identify a non-conservative tyrosine to cysteine (Y71C) missense mutation in the Islet1 gene, Isl1^Drsh. Isl1 is expressed in the normal middle ear mucosa. The findings suggest the Isl1^Drshmutation is likely to predispose carriers to otitis media.

Conclusions

Dearisch, Isl1^Drsh, represents the first point mutation in the mouse Isl1 gene and suggests a previously unrecognized role for this gene. It is also the first recorded exome sequencing of the C3HeB/FeJ background relevant to many ENU-induced mutants. Most importantly, the power of exome resequencing to identify ENU-induced mutations without a mapped gene locus is illustrated.

Evaluation of 15 functional candidate genes for association with chronic otitis media with effusion and/or recurrent otitis media (COME/ROM)

DNA sequence variants in genes involved in the innate immune response and secondary response to infection may confer susceptibility to chronic otitis media with effusion and/or recurrent otitis media (COME/ROM). We evaluated single nucleotide polymorphisms (SNPs) in 15 functional candidate genes. A total of 99 SNPs were successfully genotyped on the Sequenom platform in 142 families (618 subjects) from the Minnesota COME/ROM Family Study. Data were analyzed for association with COME/ROM using the Generalized Disequilibrium Test (GDT). Sex and age at exam were adjusted as covariates, relatedness was accounted for, and genotype differences from all phenotypically discordant relative pairs were utilized to measure the evidence of association between COME/ROM and each SNP. SNP rs2735733 in the region of the mucin 5, subtypes A/C gene (MUC5AC) exhibited nominal evidence for association with COME/ROM (P = 0.002). Two additional SNPs from this region had P values<0.05. Other variants exhibiting associations with COME/ROM at P<0.05 included the SCN1B SNP rs8100085 (P = 0.013), SFTPD SNP rs1051246 (P = 0.039) and TLR4 SNP rs2770146 (P = 0.038). However, none of these associations replicated in an independent sample of COME/ROM families. The candidate gene variants examined do not appear to make a major contribution to COME/ROM susceptibility, despite a priori evidence from functional or animal model studies for a role in COME/ROM pathology.

Innate signaling in otitis media: pathogenesis and recovery

Otitis media (OM) is the most prevalent childhood disease in developed countries. Involvement of innate immunity mediated by Toll-like receptors (TLRs) in OM has been implicated primarily in cell lines and by association studies of innate immune gene polymorphisms with OM prevalence. However, the precise role of innate immunity in OM is incompletely understood. We review recent research that has advanced our understanding of how innate immunity in the middle ear is mediated by the interaction of pathogen molecules with receptors such as the TLRs, leading to the activation of adaptor molecules and production of proinflammatory cytokines. TLR genes and signaling molecules are upregulated in OM in a murine model. Deletion of several key innate immune genes results in persistent OM in mice, coupled with an inability to clear bacterial infection from the middle ear. It is concluded that an intact innate immune signaling system is critical to recovery from bacterial OM.

Unraveling the genetics of otitis media: from mouse to human and back again

Otitis media (OM) is among the most common illnesses of early childhood, characterised by the presence of inflammation in the middle ear cavity. Acute OM and chronic OM with effusion (COME) affect the majority of children by school age and have heritability estimates of 40-70%. However, the majority of genes underlying this susceptibility are, as yet, unidentified. One method of identifying genes and pathways that may contribute to OM susceptibility is to look at mouse mutants displaying a comparable phenotype. Single-gene mouse mutants with OM have identified a number of genes, namely, Eya4, Tlr4, p73, MyD88, Fas, E2f4, Plg, Fbxo11, and Evi1, as potential and biologically relevant candidates for human disease. Recent studies suggest that this "mouse-to-human" approach is likely to yield relevant data, with significant associations reported between polymorphisms at the FBXO11, TLR4, and PAI1 genes and disease in humans. An association between TP73 and chronic rhinosinusitis has also been reported. In addition, the biobanks of available mouse mutants provide a powerful resource for functional studies of loci identified by future genome-wide association studies of OM in humans. Mouse models of OM therefore are an important component of current approaches attempting to understand the complex genetic susceptibility to OM in humans, and which aim to facilitate the development of preventative and therapeutic interventions for this important and common disease.

Allergy is an important factor in asthma exacerbation: a pro/con debate

Allergy and allergens have been implicated in asthma and it has historically been assumed that deteriorating asthma is related to allergen exposure. In the current pro/con debate some leading academics and researchers in the field consider this notion in the light of recent evidence. They conclude that allergy does not directly cause exacerbations but suggest that it may contribute to acute asthma in a different fashion. Possibilities that are proposed by the authors include specific allergy phenotypes acting as risk factors for virus-associated exacerbations or alternatively that allergy may be implicated in the blunted innate immune responses detected in asthma.

Theories of otitis media pathogenesis, with a focus on Indigenous children

Otitis media is a common childhood illness associated with hearing loss, social disadvantage and medical costs. Prevalence and severity are high among Indigenous children. Respiratory bacterial and viral pathogens ascend the eustachian tube from the nasopharynx to the middle ear, causing inflammation, fluid accumulation, and bulging of the tympanic membrane, with or without pain. Among Australian Indigenous children, ear disease commences earlier in life, and involves multiple strains of bacterial pathogens at high density that persist longer. Persistent nasal discharge, overcrowded living conditions (particularly exposure to many children) and poor facilities for washing children perpetuate a vicious cycle of transmission and infection. Risk factors include environmental tobacco smoke, season, lack of breastfeeding, younger age and immature immune system, and possibly genetic factors. The innate immune system is a critical first response to infection, particularly as passive maternal antibodies decline and during the maturation of the infant adaptive immune response. The relative contributions of innate factors to protection from otitis media are currently not well understood. A diversity of antibodies that target strain-specific and conserved antigens are generated in response to natural exposure to otitis media pathogens (or to vaccines). Deficiencies in these antibodies may explain susceptibility to recurrent infections. Incremental contributions from all these elements are likely to be important in otitis media susceptibility versus protection. Effective medical and social strategies to prevent early age of onset are urgently needed.

CC chemokine ligand 3 overcomes the bacteriocidal and phagocytic defect of macrophages and hastens recovery from experimental otitis media in TNF-/- mice

Innate immune mechanisms are crucial in defense against bacterial illnesses in humans, as evidenced by abnormal antibacterial responses due to defects in TLR signaling, seen in children with MyD88 or IL-1R-associated kinase 4 deficiency. Otitis media (OM) is the most common disease of childhood, and the role of innate immune molecules in this disorder remains unclear. In a murine model of OM, we show that, in the absence of TNF, a key effector of innate immunity, this disease is prolonged after middle ear infection with nontypeable Haemophilus influenzae (NTHi). In the absence of TNF, mice fail to upregulate both TLRs and downstream genes and proteins, such as CCL3, resulting in defects in both inflammatory cell recruitment and macrophage function. Peritoneal macrophages of mice lacking TNF have a diminished ability to phagocytose and kill NTHi, and this defect is partially corrected in vitro by exogenous rTNF. Addition of rCCL3 alone or in combination with rTNF restores phagocytosis and killing by TNF-deficient macrophages to that of unstimulated wild-type macrophages. In vivo administration of rCCL3 to animals deficient in TNF fully restores the ability to control OM due to NTHi, whereas a CCL3-blocking Ab impaired the ability of wild-type mice to recover from OM. Thus, CCL3 is a potent downstream effector of TNF-mediated inflammation in vitro and in vivo. Manipulation of CCL3 and/or TNF may prove to be effective therapeutic approaches in OM or other conditions associated with defective TNF generation.

The toll-Like receptor adaptor TRIF contributes to otitis media pathogenesis and recovery

Background

Toll-like receptor (TLR) signalling is crucial for innate immune responses to infection. The involvement of TLRs in otitis media (OM), the most prevalent childhood disease in developed countries, has been implicated by studies in middle ear cell lines, by association studies of TLR-related gene polymorphisms, and by altered OM in mice bearing mutations in TLR genes. Activated TLRs signal via two alternative intracellular signaling molecules with differing effects; MyD88 (Myeloid differentiation primary response gene 88) inducing primarily interleukin expression and TRIF (Tir-domain-containing adaptor inducing interferon β) mediating type I interferon (IFN) expression. We tested the hypothesis that TRIF and type I IFN signaling play a role in OM, using a murine model of OM induced by non-typeable Haemophilus influenzae (NTHi). The ME inflammatory response to NTHi was examined in wild-type (WT) and TRIF-/- mice by qPCR, gene microarray, histopathology and bacterial culture.

Results

Expression of TRIF mRNA was only modesty enhanced during OM, but both type I IFN signalling genes and type I IFN-inducible genes were significantly up-regulated in WT mice. TRIF-deficient mice showed reduced but more persistent mucosal hyperplasia and less leukocyte infiltration into the ME in response to NTHi infection than did WT animals. Viable bacteria could be cultured from MEs of TRIF-/- mice for much longer in the course of disease than was the case for middle ears of WT mice.

Conclusion

Our results demonstrate that activation of TRIF/type I IFN responses is important in both the pathogenesis and resolution of NTHi-induced OM.

TLR4-mediated induction of TLR2 signaling is critical in the pathogenesis and resolution of otitis media

Otitis media is the most prevalent childhood disease in developed countries. The involvement of Toll-like receptors (TLRs) in otitis media pathophysiology has been implicated by studies in cell lines and association studies of TLR gene polymorphisms. However, precise functions of TLRs in the etiology of otitis media in vivo have not been examined. We investigated the inflammatory response to nontypeable Haemophilus influenzae using a model of otitis media in wild-type, TLR2(- /-) and TLR4(-/ -) mice by gene microarray, qPCR, immunohistochemistry, Western blot analysis and histopathology. Toll-like receptor-2(- /-) and TLR4(- /-) mice exhibited a more profound, persistent inflammation with impaired bacterial clearance compared to controls. While wild-type mice induced tumor necrosis factor-a (TNF) after non-typeable H. influenzae challenge, TLR2(-/-) and TLR4(-/-) mice lack TNF induction in the early phase of otitis media. Moreover, lack of TLR2 resulted in a late increase in IL-10 expression and prolonged failure to clear bacteria. Toll-like receptor-4(-/- ) mice showed impaired early bacterial clearance and loss of TLR2 induction in early otitis media. Our results demonstrate that both TLR2 and TLR4 signalling are critical to the regulation of infection in non-typeable H. influenzae-induced otitis media. Toll-like receptor-4 signalling appears to induce TLR2 expression, and TLR2 activation is critical for bacterial clearance and timely resolution of otitis media.

Therapeutic targeting of Toll-like receptors for infectious and inflammatory diseases and cancer

Since first being described in the fruit fly Drosophila melanogaster, Toll-like receptors (TLRs) have proven to be of great interest to immunologists and investigators interested in the molecular basis to inflammation. They recognize pathogen-derived factors and also products of inflamed tissue, and trigger signaling pathways that lead to activation of transcription factors such as nuclear factor-kappaB and the interferon regulatory factors. These in turn lead to induction of immune and inflammatory genes, including such important cytokines as tumor necrosis factor-alpha and type I interferon. Much evidence points to a role for TLRs in immune and inflammatory diseases and increasingly in cancer. Examples include clear roles for TLR4 in sepsis, rheumatoid arthritis, ischemia/reperfusion injury, and allergy. TLR2 has been implicated in similar pathologic conditions and also in systemic lupus erythematosus (SLE) and tumor metastasis. TLR7 has also been shown to be important in SLE. TLR5 has been shown to be radioprotective. Recent advances in our understanding of signaling pathways activated by TLRs, structural insights into TLRs bound to their ligands and antagonists, and approaches to inhibit TLRs (including antibodies, peptides, and small molecules) are providing possiblemeans by which to interfere with TLRs clinically. Here we review these recent advances and speculate about whether manipulating TLRs is likely to be successful in fighting off different diseases.

Association of interacting genes in the toll-like receptor signaling pathway and the antibody response to pertussis vaccination

BACKGROUND

Activation of the Toll-like receptor (TLR) signaling pathway through TLR4 may be important in the induction of protective immunity against Bordetella pertussis with TLR4-mediated activation of dendritic and B cells, induction of cytokine expression, and reversal of tolerance as crucial steps. We examined whether single nucleotide polymorphisms (SNPs) in genes of the TLR4 pathway and their interaction are associated with the response to whole-cell vaccine (WCV) pertussis vaccination in 490 one-year-old children.

METHODOLOGY/PRINCIPAL FINDINGS

We analyzed associations of 75 haplotype-tagging SNPs in genes in the TLR4 signaling pathway with pertussis toxin (PT)-IgG titers. We found significant associations between the PT-IgG titer and SNPs in CD14, TLR4, TOLLIP, TIRAP, IRAK3, IRAK4, TICAM1, and TNFRSF4 in one or more of the analyses. The strongest evidence for association was found for two SNPs (rs5744034 and rs5743894) in TOLLIP that were almost completely in linkage disequilibrium, provided statistically significant associations in all tests with the lowest p-values, and displayed a dominant mode of inheritance. However, none of these single gene associations would withstand correction for multiple testing. In addition, Multifactor Dimensionality Reduction Analysis, an approach that does not need correction for multiple testing, showed significant and strong two and three locus interactions between SNPs in TOLLIP (rs4963060), TLR4 (rs6478317) and IRAK1 (rs1059703).

CONCLUSIONS/SIGNIFICANCE

We have identified significant interactions between genes in the TLR pathway in the induction of vaccine-induced immunity. These interactions underline that these genes are functionally related and together form a true biological relationship in a protein-protein interaction network. Practically all our findings may be explained by genetic variation in directly or indirectly interacting proteins at the extra- and intracytoplasmic sites of the cell membrane of antigen-presenting cells, B cells, or both. Fine tuning of interacting proteins in the TLR pathway appears important for the induction of an optimal vaccine response.

Cytokine polymorphisms predict the frequency of otitis media as a complication of rhinovirus and RSV infections in children

Previous studies suggested that the otitis media (OM) complication rate of viral upper respiratory infection (vURI) is conditioned by genes affecting cytokine production. Two hundred and thirty children (114 male; 187 White, 25 Black; aged 1–9.3 years, average = 3.6 ± 1.6 years) were prospectively followed over the typical cold season for cold-like illness and OM. Nasopharyngeal secretion samples collected during cold-like illness and OM were assayed for upper respiratory viruses and buccal samples were assayed for TNFα (−308), IL-10(−1082, −819, −592), IL-6 (−174) and IFN-γ (+874) polymorphisms. Logistic regression was used to identify genotypes that predict OM coincident with RSV and rhinovirus (RV) infection. Of the 157 children with RV detection (79 male; 132 White, 13 Black, 12 Other; aged 3.6 ± 1.5 years), simple logistic regression identified age (B = −0.34, Z = −2.8, P < 0.01, OR = 0.71), IL-6 (B = −0.76, Z = −3.3, P < 0.01, OR = 0.47) and IL-10 (B = 0.49, Z = 2.0, P = 0.05, OR = 1.6) as significant predictors of OM coincidence. A more complex logistic regression model for RV detection that included selected OM risk factors identified these factors as well as the TNFα genotype, OM history, breastfeeding history and daily environment as significant predictors of OM coincidence. Of the 43 children with RSV detection (21 male; 35 White, 5 Black, 3 Other, aged 3.9 ± 1.7 years), logistic regression identified IL-10 (B = 1.05, Z = 2.0, P = 0.05, OR = 2.9) as a significant predictor of OM coincidence. New OM episodes coincident with evidence of RSV and RV infection were significantly more frequent in children with high production IL-10 phenotypes. The low production IL-6 and high production TNFα phenotypes also contributed to OM risk during RV detection. Cytokine polymorphisms may be one of an expectedly large number of genetic factors contributing to the known heritability of OM.

Gender-specific effects of cytokine gene polymorphisms on childhood vaccine responses

Cytokine gene polymorphisms affect vaccine responses and gender-specific effects are known for many phenotypes. Therefore, this study investigated gender-specific effects of cytokine gene polymorphisms on vaccine responses. In 263 2-year-old subjects selected for parental history of atopy, boys with IL-4 C-589T and IL-4Ralpha I50V genotypes associated with atopy had increased Diptheria Toxoid (DiphTox) and Tetanus Toxoid (TetTox) responses compared with the remaining alleles (IL-4 C-589T: DipTox p=0.01, TetTox p=0.04; IL-4Ralpha.I50V: DipTox p=0.04, TetTox p=0.08). Contrastingly, girls with IL-10 -592C genotypes associated with atopy had lower levels of DiphTox (p=0.03) and TetTox (p=0.02) responses compared with the remaining allele. Additionally, interaction effects were found for IL-4 C-589T (p=0.01) and IL-4Ralpha I50V (p=0.04) polymorphisms. In conclusion, these findings support the interaction of primary genetic and modifying factors on vaccine responses and the importance of atopic genetics to these responses.

CD14, endotoxin, and asthma risk: actions and interactions

A functional single nucleotide polymorphism in the 5 genomic region of CD14 (CD14/-159) is one of the most widely tested genetic variations in relation to asthma and associated traits. The results of these studies have shown a remarkable, statistically significant heterogeneity, with some studies indicating the T-allele as a risk factor, others the C-allele, and others finding no association. Recent studies in which exposure to house-dust endotoxin or to domestic sources of microbial exposure were assessed concomitantly with CD14/-159 have shown a consistent, replicable gene-environment interaction. Specifically, results suggest that the C-allele is a risk factor for allergic phenotypes at low levels of exposure, whereas the T-allele is a risk factor at high levels of exposure. This finding seems to be explained by a genetically-determined heterogeneity for the protective effect of microbial exposure on allergic phenotypes, with homozygotes for the C-allele showing a much stronger negative association between exposure and allergic outcomes than carries of the other two genotypes. These results suggest that the often encountered, limited replicability of genetic associations may, at least in part, be due to complex interactions between genes and environment in determining asthma-related outcomes.