The D299G/T399I Toll-like receptor 4 variant associates with body and liver fat: results from the TULIP and METSIM Studies

Advanced statistics identification of participant and treatment predictors associated with severe adverse effects induced by fluoropyrimidine-based chemotherapy

PURPOSE

Adverse effects following fluoropyrimidine-based chemotherapy regimens are common. However, there are no current accepted diagnostic markers for prediction prior to treatment, and the underlying mechanisms remain unclear. This study aimed to determine genetic and non-genetic predictors of adverse effects.

METHODS

Genomic DNA was analyzed for 25 single nucleotide polymorphisms (SNPs). Demographics, comorbidities, cancer and fluoropyrimidine-based chemotherapy regimen types, and adverse effect data were obtained from clinical records for 155 Australian White participants. Associations were determined by bivariate analysis, logistic regression modeling and Bayesian network analysis.

RESULTS

Twelve different adverse effects were observed in the participants, the most common severe adverse effect was diarrhea (12.9%). Bivariate analysis revealed associations between all adverse effects except neutropenia, between genetic and non-genetic predictors, and between 8 genetic and 12 non-genetic predictors with more than 1 adverse effect. Logistic regression modeling of adverse effects revealed a greater/sole role for six genetic predictors in overall gastrointestinal toxicity, nausea and/or vomiting, constipation, and neutropenia, and for nine non-genetic predictors in diarrhea, mucositis, neuropathy, generalized pain, hand-foot syndrome, skin toxicity, cardiotoxicity and fatigue. The Bayesian network analysis revealed less directly associated predictors (one genetic and six non-genetic) with adverse effects and confirmed associations between six adverse effects, eight genetic predictors and nine non-genetic predictors.

CONCLUSION

This study is the first to link both genetic and non-genetic predictors with adverse effects following fluoropyrimidine-based chemotherapy. Collectively, we report a wealth of information that warrants further investigation to elucidate the clinical significance, especially associations with genetic predictors and adverse effects.

TLR4 polymorphism and haplotype are associated with obesity and lipid profile in young population: a pilot study

BACKGROUND

The single nucleotide polymorphisms in the TLR4 gene can decrease or increase the response to lipopolysaccharide, increasing the susceptibility to inflammatory diseases, affecting the expression or receptor function by inducing a low-grade chronic inflammatory response.

PURPOSE

The objective of this study was to evaluate the association of SNPs - 2570 A > G (rs2737190), - 2081 G > A (rs10983755), 896 A > G (rs 4986790), and 1196 C > T (rs4986791) of the TLR4 gene with obesity and metabolic alterations in the young population.

RESULTS

In this study, it was found that the carriers of the heterozygous genotype of the SNPs - 2081 G > A, 896 A > G, and 1196 C > T confer a higher risk of developing obesity (OR = 3.73, p = 0.018; OR = 5.66, p = 0.014, and OR = 8.95, p = 0.014, respectively). Also, with the lipid profile, the SNP - 2081 G > A was associated with total cholesterol (TC) ≥ 200 mg/dL (OR = 3.91, p = 0.020) and Kannel index > 3% (OR = 4.00, p = 0.008). The SNP 896 A > G was associated with LDL-c ≥ 100 mg/dL (OR = 3.64, p = 0.040) and Kannel index > 3% (OR = 4.33, p = 0.016), and the SNP 1196 C > T was associated with TC ≥ 200 mg/dL (OR = 4.37, p = 0.048), Castelli index > 4.5/> 5% (OR = 5.33, p = 0.016), and Kannel index > 3% (OR = 16.00, p = 0.001). Finally, the AGGT haplotype was associated with Castelli index > 4.5/> 5% (OR = 5.40, p = 0.015) and Kannel index > 3% (OR = 10.46, p < 0.001), and the AAAC haplotype was associated with obesity (OR = 3.56, p = 0.020), TC ≥ 200 mg/dL (OR = 4.04, p = 0.007), LDL-c ≥ 100 mg/dL (OR = 2.98, p = 0.030) and Kannel index > 3% (OR = 4.20, p = 0.002).

CONCLUSION

The heterozygous genotype of the SNPs - 2081 G > A, 896 A > G and 1196 C > T of the TLR4 gene was associated with altered lipid profile and development of obesity in young university students of Guerrero State, Mexico.

Microbiome Dysbiosis: A Pathological Mechanism at the Intersection of Obesity and Glaucoma

The rate at which obesity is becoming an epidemic in many countries is alarming. Obese individuals have a high risk of developing elevated intraocular pressure and glaucoma. Additionally, glaucoma is a disease of epidemic proportions. It is characterized by neurodegeneration and neuroinflammation with optic neuropathy and the death of retinal ganglion cells (RGC). On the other hand, there is growing interest in microbiome dysbiosis, particularly in the gut, which has been widely acknowledged to play a prominent role in the etiology of metabolic illnesses such as obesity. Recently, studies have begun to highlight the fact that microbiome dysbiosis could play a critical role in the onset and progression of several neurodegenerative diseases, as well as in the development and progression of several ocular disorders. In obese individuals, gut microbiome dysbiosis can induce endotoxemia and systemic inflammation by causing intestinal barrier malfunction. As a result, bacteria and their metabolites could be delivered via the bloodstream or mesenteric lymphatic vessels to ocular regions at the level of the retina and optic nerve, causing tissue degeneration and neuroinflammation. Nowadays, there is preliminary evidence for the existence of brain and intraocular microbiomes. The altered microbiome of the gut could perturb the resident brain-ocular microbiome ecosystem which, in turn, could exacerbate the local inflammation. All these processes, finally, could lead to the death of RGC and neurodegeneration. The purpose of this literature review is to explore the recent evidence on the role of gut microbiome dysbiosis and related inflammation as common mechanisms underlying obesity and glaucoma.

Innate-Immunity Genes in Obesity

The main functions of adipose tissue are thought to be storage and mobilization of the body’s energy reserves, active and passive thermoregulation, participation in the spatial organization of internal organs, protection of the body from lipotoxicity, and ectopic lipid deposition. After the discovery of adipokines, the endocrine function was added to the above list, and after the identification of crosstalk between adipocytes and immune cells, an immune function was suggested. Nonetheless, it turned out that the mechanisms underlying mutual regulatory relations of adipocytes, preadipocytes, immune cells, and their microenvironment are complex and redundant at many levels. One possible way to elucidate the picture of adipose-tissue regulation is to determine genetic variants correlating with obesity. In this review, we examine various aspects of adipose-tissue involvement in innate immune responses as well as variants of immune-response genes associated with obesity.

TLR4 Receptor D299G/T399I Haplotype Polymorphism Is Associated with Insulin Resistance in Obese Female Subjects

Background: Activation of Toll-like-receptor 4 (TLR4) causes chronic inflammation that can result in obesity and metabolic syndrome (MeS). Aim: This study aimed to investigate the role of TLR4 polymorphisms of TLR4D299G/T399I, and its impact on protein expression of TLR4 in obese female subjects. Methodology: A prospective cross-sectional association study was performed on Arab female subjects from Qatar University. The subjects were categorized according to BMI classifications into two groups: “obese; n = 69” and “non-obese; n = 136”. Anthropometric measurements, weight (kg), height (m) and waist circumference (WC) were evaluated, and the body mass index (BMI) was calculated. Fasting blood samples were collected, and assessment of glucose, lipid profile, C-reactive protein (CRP), leptin, IL-6 and insulin was performed. Insulin resistance was computed using HOMA-IR. Genotyping of the TLR4 polymorphisms of TLR4D299G (rs4986790) and TLR4T399I (rs4986791) was performed by the 5′ nuclease assay by TaqMan MGB probe. Flow cytometry was used to evaluate the monocyte cell surface expression of TLR4. Results: The frequency distribution of the genotype revealed that homozygous AA is the most frequent among obese subjects (86.4%) for (TLR4D299G, A > G) and the homozygous CC genotype is the most frequent (92.4%) for (TLR4T399I, C > T). Haplotype analysis of TLR4 D299G/T399I showed that GT carriers had a significant association with increased probability of insulin resistance (odds ratio = 4.73; 95% CI 1.19–18.90; p-value = 0.016). The monocyte cell surface of TLR4 was significantly higher by 1.3 folds in obese compared to non-obese subjects. Conclusions: TLR4 D299G/T399I haplotype polymorphism is associated with an increased risk of insulin resistance with the upregulation of TLR4 protein expression in obese subjects.

Pattern recognition receptors as potential therapeutic targets in metabolic syndrome: From bench to bedside

Pattern recognition receptors (PRRs) such as Toll-like receptors (TLRs) and NOD-like receptors (NLRs) play crucial roles in the underlying mechanisms of metabolic syndrome (MetS). Mainly, these receptors have been suggested to participate in the pathophysiological processes involved in the complications associated with this condition. Therefore, to evolve therapeutic strategies targeting PRRs might be an imperative approach to avoid the development of further complications in human subjects. In this work, we discuss the understanding regarding the roles of PRRs in the pathways of MetS to further describe potential advancements made to target these receptors within this pathology.

Multidisciplinary Roles of LRRFIP1/GCF2 in Human Biological Systems and Diseases

Leucine Rich Repeat of Flightless-1 Interacting Protein 1/GC-binding factor 2 (LRRFIP1/GCF2) cDNA was cloned for a transcriptional repressor GCF2, which bound sequence-specifically to a GC-rich element of epidermal growth factor receptor (EGFR) gene and repressed its promotor. LRRFIP1/GCF2 was also cloned as a double stranded RNA (dsRNA)-binding protein to trans-activation responsive region (TAR) RNA of Human Immunodeficiency Virus-1 (HIV-1), termed as TAR RNA interacting protein (TRIP), and as a binding protein to the Leucine Rich Repeat (LRR) of Flightless-1(Fli-1), termed as Flightless-1 LRR associated protein 1 (FLAP1) and LRR domain of Flightless-1 interacting Protein 1 (LRRFIP1). Subsequent functional studies have revealed that LRRFIP1/GCF2 played multiple roles in the regulation of diverse biological systems and processes, such as in immune response to microorganisms and auto-immunity, remodeling of cytoskeletal system, signal transduction pathways, and transcriptional regulations of genes. Dysregulations of LRRFIP1/GCF2 have been implicated in the causes of several experimental and clinico-pathological states and the responses to them, such as autoimmune diseases, excitotoxicity after stroke, thrombosis formation, inflammation and obesity, the wound healing process, and in cancers. LRRFIP1/GCF2 is a bioregulator in multidisciplinary systems of the human body and its dysregulation can cause diverse human diseases.

TLR4 polymorphisms seem not to be associated with prediabetes and type 2 diabetes but predispose to diabetic retinopathy; TLR4 polymorphisms in glucose continuum

OBJECTIVES

Compared to type 1 diabetes, the role of the immune and autoimmune pathogenetic mechanisms is much less studied in the type 2 diabetes. Toll-like receptors 4 (TLR4) have a leading role in inflammation, insulin resistance, and vascular damage. This study aimed to analyze the relationship between the polymorphisms in TLR4 gene and different stages in the glucose continuum from prediabetes to the type 2 diabetes and chronic microvascular complications.

MATERIALS AND METHODS

The study included 113 patients with the type 2 diabetes, 29 participants with prediabetes, and 28 controls. Polymerase chain reaction (PCR) was used for genotyping Asp299Gly and Thr399Ile polymorphism, followed by restriction analysis.

RESULTS

The difference in the genotype frequency for both polymorphisms in patients with the type 2 diabetes or prediabetes compared to that in controls was not significant. Patients with heterozygous genotype of Asp299Gly polymorphism had a higher prevalence of diabetic retinopathy (42.9%) than participants with homozygous genotype (9.0%) (OR [95%CI]=7.61 [1.41-41.08]; p=0.018). No association was established for diabetic polyneuropathy and nephropathy. Prevalence of chronic diabetes complications was not related to Thr399Ile polymorphism.

CONCLUSION

Our study demonstrates that Asp299Gly and Thr399Ile polymorphisms seem not to be associated with the type 2 diabetes and prediabetes but Asp299Gly may contribute to diabetic retinopathy predisposition.

Expression level of human TLR4 rather than sequence is the key determinant of LPS responsiveness

To address the role of Toll-like receptor 4 (TLR4) single nucleotide polymorphisms (SNP) in lipopolysaccharide (LPS) recognition, we generated mice that differed only in the sequence of TLR4. We used a bacterial artificial chromosome (BAC) transgenic approach and TLR4/MD-2 knockout mice to specifically examine the role of human TLR4 variants in recognition of LPS. Using in vitro and in vivo assays we found that the expression level rather than the sequence of TLR4 played a larger role in recognition of LPS, especially hypoacylated LPS.

Genetic Variants in Toll-Like Receptor 4 Gene and Their Association Analysis with Estimated Glomerular Filtration Rate in Mexican American Families

BACKGROUND/AIM

Toll-like receptor 4 (TLR4) is one of the regulators of the innate immune response. Genetic variations in TLR4 have been associated with inflammatory diseases, including type 2 diabetes. However, to our knowledge, there are no reports on the role of variations in TLR4 in chronic kidney disease susceptibility. The objective of this study is to determine whether the genetic variants in TLR4 are associated with the estimated glomerular filtration rate (eGFR), a measure of renal function.

METHODS

To evaluate the association between TLR4 variants and eGFR, we used data obtained from 434 Mexican American participants from the San Antonio Family Diabetes/Gallbladder Study. GFR was estimated using the Modification of Diet in Renal Disease formula. The Asp(299)Gly (rs4986790) and Thr(399)Ile (rs4986791) variants of TLR4 were genotyped using the TaqMan assay. Association analyses between genotypes and eGFR were performed using the measured genotype approach.

RESULTS

Of the two genetic markers examined for association, only the Asp(299)Gly variant of TLR4 exhibited a nominally significant association with eGFR (p = 0.025) after accounting for the covariate effects of age and sex terms, diabetes, duration of diabetes, systolic blood pressure, body mass index, and antihypertensive treatment. Carriers of Gly299 had significantly decreased eGFR values. Although, the Thr(399)Ile variant failed to exhibit a statistically significant association with eGFR, the carriers of Ile399, however, showed a trend towards decrease in eGFR.

CONCLUSION

We show for the first time that Asp(299)Gly variants of TLR4 are associated with decrease in renal function in Mexican Americans.

Genetic basis of interindividual susceptibility to cancer cachexia: selection of potential candidate gene polymorphisms for association studies

Cancer cachexia is a complex and multifactorial disease. Evolving definitions highlight the fact that a diverse range of biological processes contribute to cancer cachexia. Part of the variation in who will and who will not develop cancer cachexia may be genetically determined. As new definitions, classifications and biological targets continue to evolve, there is a need for reappraisal of the literature for future candidate association studies. This review summarizes genes identified or implicated as well as putative candidate genes contributing to cachexia, identified through diverse technology platforms and model systems to further guide association studies. A systematic search covering 1986-2012 was performed for potential candidate genes / genetic polymorphisms relating to cancer cachexia. All candidate genes were reviewed for functional polymorphisms or clinically significant polymorphisms associated with cachexia using the OMIM and GeneRIF databases. Pathway analysis software was used to reveal possible network associations between genes. Functionality of SNPs/genes was explored based on published literature, algorithms for detecting putative deleterious SNPs and interrogating the database for expression of quantitative trait loci (eQTLs). A total of 154 genes associated with cancer cachexia were identified and explored for functional polymorphisms. Of these 154 genes, 119 had a combined total of 281 polymorphisms with functional and/or clinical significance in terms of cachexia associated with them. Of these, 80 polymorphisms (in 51 genes) were replicated in more than one study with 24 polymorphisms found to influence two or more hallmarks of cachexia (i.e., inflammation, loss of fat mass and/or lean mass and reduced survival). Selection of candidate genes and polymorphisms is a key element of multigene study design. The present study provides a contemporary basis to select genes and/or polymorphisms for further association studies in cancer cachexia, and to develop their potential as susceptibility biomarkers of cachexia.

Association of Toll-like Receptor 4 Gene polymorphisms with susceptibility to type 2 diabetes mellitus in the Chinese population

BACKGROUND

Toll-like receptor 4 (TLR4) plays an important role in innate immunity. Activation of innate immune response and subsequent chronic low-grade inflammation are thought to be involved in the pathogenesis of type 2 diabetes. In this study, we aimed to investigate the association of TLR4 variants with type 2 diabetes in the Chinese population.

METHODS

Seven tag single nucleotide polymorphisms (SNPs) of TLR4 based on HapMap Chinese data were genotyped in the Shanghai Chinese, including 3404 type 2 diabetes patients and 3401 controls. The controls were extensively phenotyped for the traits related to glucose metabolism and insulin secretion.

RESULTS

In total participants, we identified that rs10759932 and rs1927911 were associated with type 2 diabetes (odds ratio 1.106, P = 0.009 for rs10759532, odds ratio 1.092, P = 0.013 for rs1927911). rs11536889 showed a trend association with type 2 diabetes (odds ratio 0.957, P = 0.057). This SNP was also associated with 2-h plasma glucose (P = 0.033) and high-density lipoprotein-cholesterol (P = 0.031). In female participants, rs10759932, rs1927911 and rs11536889 were associated with type 2 diabetes (odds ratio 1.176, P = 0.002 for rs10759932, odds ratio 1.136, P = 0.009 for rs1927911, odds ratio 0.882, P = 0.024 for rs11536889). Besides, rs11536889 was significantly associated with 2-h plasma glucose (P = 0.050) and HOMA-B (P = 0.046) with adjusting for age and body mass index in female normal subjects.

CONCLUSIONS

We conclude that genetic variants of TLR4 are associated with type 2 diabetes in the Chinese population, especially in female subjects.

TLR4 at the Crossroads of Nutrients, Gut Microbiota, and Metabolic Inflammation

Obesity is accompanied by the activation of low-grade inflammatory activity in metabolically relevant tissues. Studies have shown that obesity-associated insulin resistance results from the inflammatory targeting and inhibition of key proteins of the insulin-signaling pathway. At least three apparently distinct mechanisms-endoplasmic reticulum stress, toll-like receptor (TLR) 4 activation, and changes in gut microbiota-have been identified as triggers of obesity-associated metabolic inflammation; thus, they are expected to represent potential targets for the treatment of obesity and its comorbidities. Here, we review the data that place TLR4 in the center of the events that connect the consumption of dietary fats with metabolic inflammation and insulin resistance. Changes in the gut microbiota can lead to reduced integrity of the intestinal barrier, leading to increased leakage of lipopolysaccharides and fatty acids, which can act upon TLR4 to activate systemic inflammation. Fatty acids can also trigger endoplasmic reticulum stress, which can be further stimulated by cross talk with active TLR4. Thus, the current data support a connection among the three main triggers of metabolic inflammation, and TLR4 emerges as a link among all of these mechanisms.

The genetics of innate immunity sensors and human disease

Since their discovery, innate immunity microbial sensors have been increasingly studied and shown to play a critical role in innate responses to microbes in several experimental in vitro, ex vivo, and animal models. However, their role in the human response to infection in natural conditions has just started to be deciphered, by means of clinical studies of primary immunodeficiencies and epidemiological genetic studies. Here, we summarize the major findings concerning the genetic diversity of the various families of microbial sensors in humans, and of other molecules involved in the signaling pathways they trigger. Specifically, we review the genetic associations, revealed by both clinical and epidemiological genetics studies, of microbial sensors from five different families: Toll-like receptors, C-type lectin receptors, NOD-like receptors, RIG-I-like receptors, and cytosolic DNA sensors. In particular, we consider the relationships between variation at the genes encoding these molecules and susceptibility to and the severity of infectious diseases and other clinical conditions associated with immune dysfunction, including autoimmunity, inflammation, allergy, and cancer. Despite the fact that the genetic links between innate immunity sensors and human disorders remain still limited, human genetics studies are increasingly improving our understanding of the genuine functions of microbial sensors and downstream signaling molecules in the natural setting.

A nonsense polymorphism (R392X) in TLR5 protects from obesity but predisposes to diabetes

The TLR5 gene encodes an innate immunity receptor. Mice lacking Tlr5 (T5KO) develop insulin resistance and increased adiposity. Owing to the segregation of a dominant nonsense polymorphism (R392X, rs5744168), a portion of humans lack TLR5 function. We investigated whether the nonsense polymorphism influences obesity and susceptibility to type 2 diabetes (T2D). R392X was genotyped in two cohorts from Saudi Arabia, a region where obesity and type 2 diabetes (T2D) are highly prevalent. The nonsense allele was found to protect from obesity (p(combined) = 0.0062; odds ratio, 0.51) and to associate with lower body mass index (BMI) (p(combined) = 0.0061); this allele also correlated with a reduced production of proinflammatory cytokines. A significant interaction was noted between rs5744168 and sex in affecting BMI (p(interaction) = 0.006), and stratification by gender revealed that the association is driven by females (p(combined) = 0.0016 and 0.0006 for obesity and BMI, respectively). The nonsense polymorphism also associated with BMI in nonobese women. After correction for BMI, the 392X allele was found to represent a risk factor for T2D with a sex-specific effect (p(interaction) = 0.023) mediated by females (p = 0.021; odds ratio, 2.60). Fasting plasma glucose levels in nondiabetic individuals were also higher in women carrying the nonsense allele (p = 0.012). Thus, in contrast to T5KO mice, loss of human TLR5 function protects from weight gain, but in analogy to the animal model, the nonsense allele predisposes to T2D. These effects are apparently sex-specific. Data in this study reinforce the hypothesis that metabolic diseases, including T2D, are associated with immune dysregulation.

Within-person variation in the postprandial lipemic response of healthy adults

BACKGROUND

The response to dietary fat plays a key role in metabolic health. Although this can vary widely between individuals, variation within an individual and the associated contribution of phenotypic and genotypic factors to this variation are less defined.

OBJECTIVES

The objectives were to quantify within-person variation in triacylglycerol response by means of a novel variation score (S(v)) and to explore the phenotypic and genotypic factors associated with this score.

DESIGN

Two consecutive 5-h oral-lipid-tolerance tests (OLTTs) were conducted in 51 healthy adults aged 18-60 y with a BMI (in kg/m²) of 18.5 to 49.8. Detailed body composition, physical function, biochemistry, and genotype data were gathered.

RESULTS

The postprandial triacylglycerol response profile did not differ (P = 0.64) across OLTTs for the group; nor did average concentrations of functional markers apolipoprotein C2 (P = 0.73) and apolipoprotein C3 (P = 0.74). S(v) was low in most (82%) of the adults and was significantly (P < 0.05) associated with age, fasting triacylglycerol, triacylglycerol AUC, and fasting nonessential fatty acids. Significant associations were also observed between S(v) and single nucleotide polymorphisms in 7 genes (APOA1, IL1α, IL1β, TLR4, TCF7L2, CCK1Rec, and STAT3) after correction for phenotypic differences.

CONCLUSIONS

This work showed that the within-person variability in postprandial lipemic response is low in most healthy adults. It also showed that variability in this response is associated with a defined set of phenotypic and genotypic characteristics.

Innate immune function by Toll-like receptors: distinct responses in newborns and the elderly

Given the "inborn" nature of the innate immune system, it is surprising to find that innate immune function does in fact change with age. Similar patterns of distinct Toll-like-receptor-mediated immune responses come to light when one contrasts innate immune development at the beginning of life with that toward the end of life. Importantly, these developmental patterns of innate cytokine responses correlate with clinical patterns of susceptibility to disease: A heightened risk of suffering from excessive inflammation is often detected in prematurely born infants, disappears over the first few months of life, and reappears toward the end of life. In addition, risk periods for particular infections in early life reemerge in older adults. The near-mirror-image patterns that emerge in contrasts of early versus late innate immune ontogeny emphasize changes in host-environment interactions as the underlying molecular and teleologic drivers.

A variant in the LRRFIP1 gene is associated with adiposity and inflammation

Inflammation is an important factor linking abdominal obesity with insulin resistance and related cardiometabolic risk. A genome-wide association study of adiposity-related traits performed in the Quebec Family Study (QFS) revealed that a single-nucleotide polymorphism (SNP) in the LRRFIP1 gene (rs11680012) was associated with abdominal adiposity (P = 4.6 × 10(-6)).

OBJECTIVE

The objective of this study was to assess the relationship between polymorphisms in LRRFIP1 gene and adiposity (BMI, fat mass (FM), waist circumference (WC), and computed tomography-derived areas of total, subcutaneous and visceral abdominal adipose tissue) and markers of inflammation (C-reactive protein (CRP) and interleukin-6 (IL-6)).

DESIGN AND METHODS

Using Sequenom, 16 tag SNPs in the LRRFIP1 gene, capturing 78% of the genetic variation, were genotyped in 926 participants of the QFS.

RESULTS

Eight SNPs (rs7575941, rs3769053, rs11689421, rs3820808, rs11680012, rs3806505, rs6739130, and rs11686141) showed evidence of association with at least two adiposity phenotypes and plasma levels of one marker of inflammation. The strongest evidence of association was observed with rs11680012, which explained 1.8-3.4% of the variance in areas of abdominal adiposity and 2.0% of the variation in CRP levels. Carriers of the rare allele of rs11680012 had ≈ 30% more abdominal adiposity (P values between 2.7 × 10(-4) and 3.8 × 10(-6)) and 75% higher CRP levels (P = 1.6 × 10(-4)) than the common allele in age and sex adjusted data. Rs11680012 is a G/C SNP converting an arginine into a threonine and this amino acid substitution may potentially alter exonic splicing.

CONCLUSION

This gene may therefore represent a potential interesting target to investigate in further functional studies on adiposity and inflammation.

CD14 deficiency impacts glucose homeostasis in mice through altered adrenal tone

The toll-like receptors comprise one of the most conserved components of the innate immune system, signaling the presence of molecules of microbial origin. It has been proposed that signaling through TLR4, which requires CD14 to recognize bacterial lipopolysaccharide (LPS), may generate low-grade inflammation and thereby affect insulin sensitivity and glucose metabolism. To examine the long-term influence of partial innate immune signaling disruption on glucose homeostasis, we analyzed knockout mice deficient in CD14 backcrossed into the diabetes-prone C57BL6 background at 6 or 12 months of age. CD14-ko mice, fed either normal or high-fat diets, displayed significant glucose intolerance compared to wild type controls. They also displayed elevated norepinephrine urinary excretion and increased adrenal medullary volume, as well as an enhanced norepinephrine secretory response to insulin-induced hypoglycemia. These results point out a previously unappreciated crosstalk between innate immune- and sympathoadrenal- systems, which exerts a major long-term effect on glucose homeostasis.

Nasopharyngeal bacterial colonization and gene polymorphisms of mannose-binding lectin and toll-like receptors 2 and 4 in infants

BACKGROUND

Human nasopharynx is often colonized by potentially pathogenic bacteria. Gene polymorphisms in mannose-binding lectin (MBL), toll-like receptor (TLR) 2 and TLR4 have been reported. The present study aimed to investigate possible association between nasopharyngeal bacterial colonization and gene polymorphisms of MBL, TLR2 and TLR4 in healthy infants.

METHODOLOGY/PRINCIPAL FINDINGS

From August 2008 to June 2010, 489 nasopharyngeal swabs and 412 blood samples were taken from 3-month-old healthy Finnish infants. Semi-quantitative culture was performed and pyrosequencing was used for detection of polymorphisms in MBL structural gene at codons 52, 54, and 57, TLR2 Arg753Gln and TLR4 Asp299Gly. Fifty-nine percent of subjects were culture positive for at least one of the four species: 11% for Streptococcus pneumoniae, 23% for Moraxella catarrhalis, 1% for Haemophilus influenzae and 25% for Staphylococcus aureus. Thirty-two percent of subjects had variant types in MBL, 5% had polymorphism of TLR2, and 18% had polymorphism of TLR4. Colonization rates of S. pneumoniae and S. aureus were significantly higher in infants with variant types of MBL than those with wild type (p = .011 and p = .024). Colonization rates of S. aureus and M. catarrhalis were significantly higher in infants with polymorphisms of TLR2 and of TLR4 than those without (p = .027 and p = .002).

CONCLUSIONS

Our study suggests that there is an association between nasopharyngeal bacterial colonization and genetic variation of MBL, TLR2 and TLR4 in young infants. This finding supports a role for these genetic variations in susceptibility of children to respiratory infections.

Toll-like receptor 2 and 4 stimulation elicits an enhanced inflammatory response in human obese patients with atherosclerosis

The innate immune response elicited by activation of TLRs (Toll-like receptors) plays an important role in the pathogenesis of atherosclerosis. We hypothesized that cardiovascular risk factors are associated with the activation status of the innate immune system. We therefore assessed the responsiveness of TLRs on circulating cells in two groups of patients with established atherosclerosis and related this to the presence of cardiovascular risk factors. TNF (tumour necrosis factor)-α release induced by TLR2 and TLR4 activation was measured in patients with established coronary [PCI (percutaneous coronary intervention) study, n=78] or carotid artery disease [CEA (carotid endarterectomy) study, n=104], by stimulating whole blood samples with lipopolysaccharide (TLR4 ligand) and Pam3CSK4 [tripalmitoylcysteinylseryl-(lysyl)4; TLR2 ligand]. As an early activation marker, CD11b expression was measured by flow cytometry on CD14+ cells. Obesity was the ‘only’ risk factor that correlated with the TLR response. In both studies, obese patients had significantly higher TNF-α levels after stimulation of TLR2 compared with non-obese patients [16.9 (7.7–49.4) compared with 7.5 (1.5–19.2) pg/ml (P=0.008) in coronary artery disease and 14.6 (8.1–28.4) compared with 9.5 (6.1–15.7) pg/ml (P=0.015) in carotid artery disease; values are medians (interquartile range)]. Similar results were obtained following TLR4 stimulation. The enhanced inflammatory state in obese patients was also confirmed by a significant increased expression of the activation marker CD11b on circulating monocytes. In conclusion, obesity is associated with an enhanced TLR response in patients suffering from established atherosclerotic disease.