Contribution of the familial and genetic factors on monocyte chemoattractant protein-1 variation in healthy human pedigrees

Monocyte chemoattractant protein-1 (MCP-1) is a chemokine whose circulating levels have been detected in the lesions of several diseases such as pulmonary fibrosis, rheumatoid arthritis and atherosclerosis. However, the factors involved in the regulation of its production remain largely unknown. The main aim of the present paper was to ascertain the contribution of the familial/genetic factors on the production of MCP-1 in apparently healthy individuals. We also tested the possible relationships between the plasma levels of MCP-1 and other cytokines involved in bone metabolism (receptor activator NF-kB ligand (RANKL), osteoprotegerin (OPG), interleukin-6, macrophage-colony stimulating factor, tumor necrosis factor-alpha). Using ELISA assays the cytokine levels were measured in 570 apparently healthy individuals belonging to ethnically homogeneous Caucasian families. We found that MCP-1 levels were significantly (P<0.01) correlated with RANKL (in both sexes) and with OPG only in women. The study showed that adjusted for potential covariates, 72% of the MCP-1 variance, was attributable to familial effects. About 49% was due to potential genetic factors and the rest was explained by common environmental sources shared by spouses within each family. In conclusion, our data provide reliable evidence for the substantial role of genetic factors in the determination of the phenotypic variability of MCP-1 plasma levels. The association between the osteoclastogenic cytokines and MCP-1 levels in healthy pedigrees is of special interest and might shed light on MCP-1 involvement in bone remodeling.     

Heritability of circulating growth factors involved in the angiogenesis in healthy human population

The present study examined the extent of genetic and environmental influences on the populational variation of circulating growth factors (VEGF, EGF) involved in angiogenesis in healthy and ethnically homogeneous Caucasian families. The plasma levels of each of the studied biochemical indices were determined by enzyme-linked immunoassay in 478 healthy individuals aged 18-75 years. Quantitative genetic analysis showed that the VEGF and EGF variation was appreciably attributable to genetic effects, with heritability estimates of 79.9% and 48.4%, respectively. Yet, common environmental factors, shared by members of the same household, also played a significant role (P < 0.01) and explained between 20.1% and 32.6% of the variation. The present study additionally examined the covariations between these molecules and either transforming growth factor-beta 1 (TGF-beta 1) or tissue inhibitors of matrix metalloproteinases 1 (TIMP-1), likewise relevant for angiogenesis. Bivariate analysis revealed significant phenotypic correlations (P < 0.002) between all pairs of variables, thus indicating the possible existence of common genetic and environmental factors. The analysis suggested that the pleiotropic genetic effects were consistently the primary (or even the sole) source of correlation between all pairs of studied molecules. The results of our study affirm the existence of specific and common genetic pathways that commonly determine the greater part of the circulating variation of these molecules.     

骨骼的内分泌功能

既往认为骨骼是支持机体基本结构和参与运动及钙磷代谢的主要器官。近年发现组成骨骼的成骨细胞和破骨细胞能合成和分泌多种骨调节蛋白、生长因子、脂肪因子、炎症因子和心血管活性肽等多种生物活性物质,以旁/自分泌方式调节骨骼系统功能,并能通过血液循环远距分泌的方式,调节机体能量代谢、炎症反应和内分泌稳态等。     

Interleukin-1 alpha (IL-1 alpha) and tumor necrosis factor alpha (TNF alpha) regulate insulin-like growth factor binding protein-1 (IGFBP-1) levels and mRNA abundance in vivo and in vitro.

TNF alpha and IL-1 alpha are thought to contribute to impaired anabolism in a variety of clinical states, including sepsis, cancer cachexia and the AIDS wasting syndrome. We asked whether cytokines exert direct effects on hepatic production of IGFBP-1, an important modulator of IGF bioavailability. C57BL/6 mice were treated with 100 micrograms/kg of recombinant IL-1 alpha or TNF alpha by intraperitoneal injection. Western ligand blotting and immunoprecipitation with specific antisera revealed that serum levels of IGFBP-1 (but not IGFBP-2, -3, -4, -5 or -6) are increased approximately 4 fold 2 h after treatment and then decline. Northern blotting confirms that hepatic IGFBP-1 mRNA abundance also is increased acutely in both IL-1 alpha- and TNF alpha-treated animals. Similar results obtained in adrenalectomized mice indicate that adrenal activation is not required for this effect. Cell culture studies show that cytokines exert direct effects on the production of IGFBP-1 by HepG2 hepatoma cells, increasing IGFBP-1 levels in conditioned medium and the abundance of IGFBP-1 mRNA approximately 3-fold. In contrast, transient transfection studies with IGFBP-1 promoter/luciferase reporter gene constructs show that IGFBP-1 promoter activity is reduced after 18 hr cytokine treatment. We conclude that IL-1 alpha and TNF alpha increase circulating levels of IGFBP-1, reflecting direct effects on hepatic IGFBP-1 mRNA abundance. Stimulation of hepatic IGFBP-1 production may contribute to alterations in IGF bioactivity and impaired anabolism in clinical conditions where cytokine production is high. Additional studies are required to identify specific mechanisms mediating effects of cytokines on hepatic production of IGFBP-1.     

Susceptibility to cholesterol gallstone formation: evidence that LITH genes also encode immune-related factors

Cholesterol gallstones are solid calculi that form in the gallbladder from bile constituents and chiefly comprise cholesterol. Cholesterol gallstones are prevalent and costly for healthcare systems. In addition to various environmental factors, genetic risk contributes substantially to gallstone susceptibility. Candidate gene approaches to identify contributory genes are based on prior knowledge of gene-protein function. Whether selected from the entire genome or from limited genomic regions detected by experimental linkage analyses, thus far, candidate genes predominantly were related to lipid homeostasis. Alternatively, comprehensive review of available data suggests that a fundamental driving force underlying cholesterol gallstone formation is inflammation. Therefore, we predict that Lith genes in mice and LITH genes in humans also encode inflammatory molecules, their receptors and other mediators. Indeed, many Lith loci, defined experimentally using inbred mouse models, co-localise with genes that encode inflammation-related proteins. Systematic review of the literature reveals evidence consistent with inflammatory responses that may dictate each of the three cornerstones of cholesterol gallstone formation: biliary cholesterol supersaturation; cholesterol nucleation; gallbladder hypomotility. Genetically targeted inbred mice represent a powerful tool to interrogate the relationship between immune-related genes and gallstone susceptibility. We urge researchers to consider inflammation-related genes when designing population case-control genetic association studies pertaining to the genetic basis of gallstones. Immune and inflammatory events underlie each criterion necessary for cholesterol gallstone formation, which suggests that variation within the respective genes is fundamental for gallstone formation. In turn, inflammatory mediators may exert a spectrum of effects in response to genetic variation within lipid homeostatic genes.     

Interindividual methylomic variation across blood,cortex, and cerebellum: implications for epigenetic studies of neurological and neuropsychiatric phenotypes

Given the tissue-specific nature of epigenetic processes, the assessment of disease-relevant tissue is an important consideration for epigenome-wide association studies (EWAS). Little is known about whether easily accessible tissues, such as whole blood, can be used to address questions about interindividual epigenomic variation in inaccessible tissues, such as the brain. We quantified DNA methylation in matched DNA samples isolated from whole blood and 4 brain regions (prefrontal cortex, entorhinal cortex, superior temporal gyrus, and cerebellum) from 122 individuals. We explored co-variation between tissues and the extent to which methylomic variation in blood is predictive of interindividual variation identified in the brain. For the majority of DNA methylation sites, interindividual variation in whole blood is not a strong predictor of interindividual variation in the brain, although the relationship with cortical regions is stronger than with the cerebellum. Variation at a subset of probes is strongly correlated across tissues, even in instances when the actual level of DNA methylation is significantly different between them. A substantial proportion of this co-variation, however, is likely to result from genetic influences. Our data suggest that for the majority of the genome, a blood-based EWAS for disorders where brain is presumed to be the primary tissue of interest will give limited information relating to underlying pathological processes. These results do not, however, discount the utility of using a blood-based EWAS to identify biomarkers of disease phenotypes manifest in the brain. We have generated a searchable database for the interpretation of data from blood-based EWAS analyses (http://epigenetics.essex.ac.uk/bloodbrain/).     

Disease-specific dynamic biomarkers selected by integrating inflammatory mediators with clinical informatics in ARDS patients with severe pneumonia

Acute respiratory distress syndrome (ARDS) is a heterogeneous syndrome that occurs as a result of various risk factors, including either direct or indirect lung injury, and systemic inflammation triggered also by severe pneumonia (SP). SP-ARDS-associated morbidity and mortality remains high also due to the lack of disease-specific biomarkers. The present study aimed at identifying disease-specific biomarkers in SP or SP-ARDS by integrating proteomic profiles of inflammatory mediators with clinical informatics. Plasma was sampled from the healthy as controls or patients with SP infected with bacteria or infection-associated SP-ARDS on the day of admission, day 3, and day 7. About 15 or 52 cytokines showed significant difference between SP and SP-ARDS patients with controls or 13 between SP-ARDS with SP alone and controls, including bone morphogenetic protein-15 (BMP-15), chemokine (C-X-C motif) ligand 16 (CXCL16), chemokine (C-X-C motif) receptor 3 (CXCR3), interleukin-6 (IL-6), protein NOV homolog (NOV/CCN3), glypican 3, insulin-like growth factor binding protein 4 (IGFBP-4), IL-5, IL-5 R alpha, IL-22 BP, leptin, MIP-1d, and orexin B with a significant correlation with Digital Evaluation Score System (DESS) scores. ARDS patients with overexpressed IL-6, CXCL16, or IGFBP-4 had significantly longer hospital stay and higher incidence of secondary infection. We also found higher levels of those mediators were associated with poor survival rates in patients with lung cancer and involved in the process of the epithelial mesenchymal transition of alveolar epithelial cells. Our preliminary study suggested that integration of proteomic profiles with clinical informatics as part of clinical bioinformatics is important to validate and optimize disease-specific and disease-staged biomarkers.     

PAPPA2, an enzyme that cleaves an insulin-like growth-factor-binding protein, is a candidate gene for a quantitative trait locus affecting body size in mice

Identifying genes responsible for quantitative variation remains a major challenge. We previously identified a quantitative trait locus (QTL) affecting body size that segregated between two inbred strains of mice. By fine mapping, we have refined the location of this QTL to a genomic region containing only four protein-coding genes. One of these genes, PAPPA2, is a strong candidate because it codes for an enzyme that cleaves insulin-like growth-factor-binding protein 5 (IGFBP-5), an important stimulator of bone formation. Among littermates that segregate only for the four-gene region, we show that the QTL has a significant effect on the circulating levels of IGFBP-5 and IGFBP-3 (the latter subject to limited degradation by PAPPA2), but not on levels of IGFBP-2 and IGFBP-4, which are not cleaved by PAPPA2. There are 14 nonsynonymous SNPs among QTL alleles, which may affect the activity of the translated protein. The refinement of the target region to four genes and the finding that the QTL affects IGFBP-5 levels suggest that PAPPA2 may be involved with normal postnatal growth. Our mapping results also illustrate the potentially fractal nature of QTL: as we mapped our QTL with increasing resolution, what appeared to be a single QTL resolved into three closely linked QTL (previous work), and then one of these was further dissected into two in this study.     

IGF-1, IGFBP-1, and IGFBP-3 polymorphisms predict circulating IGF levels but not breast cancer risk: findings from the Breast and Prostate Cancer Cohort Consortium (BPC3)

IGF-1 has been shown to promote proliferation of normal epithelial breast cells, and the IGF pathway has also been linked to mammary carcinogenesis in animal models. We comprehensively examined the association between common genetic variation in the IGF1, IGFBP1, and IGFBP3 genes in relation to circulating IGF-I and IGFBP-3 levels and breast cancer risk within the NCI Breast and Prostate Cancer Cohort Consortium (BPC3). This analysis included 6,912 breast cancer cases and 8,891 matched controls (n = 6,410 for circulating IGF-I and 6,275 for circulating IGFBP-3 analyses) comprised primarily of Caucasian women drawn from six large cohorts. Linkage disequilibrium and haplotype patterns were characterized in the regions surrounding IGF1 and the genes coding for two of its binding proteins, IGFBP1 and IGFBP3. In total, thirty haplotype-tagging single nucleotide polymorphisms (htSNP) were selected to provide high coverage of common haplotypes; the haplotype structure was defined across four haplotype blocks for IGF1 and three for IGFBP1 and IGFBP3. Specific IGF1 SNPs individually accounted for up to 5% change in circulating IGF-I levels and individual IGFBP3 SNPs were associated up to 12% change in circulating IGFBP-3 levels, but no associations were observed between these polymorphisms and breast cancer risk. Logistic regression analyses found no associations between breast cancer and any htSNPs or haplotypes in IGF1, IGFBP1, or IGFBP3. No effect modification was observed in analyses stratified by menopausal status, family history of breast cancer, body mass index, or postmenopausal hormone therapy, or for analyses stratified by stage at diagnosis or hormone receptor status. In summary, the impact of genetic variation in IGF1 and IGFBP3 on circulating IGF levels does not appear to substantially influence breast cancer risk substantially among primarily Caucasian postmenopausal women.     

Linkage of interleukin 6 locus to human osteopenia by sibling pair analysis

Osteopenia and osteoporosis are common human conditions considered to result from the interplay of multiple genetic and environmental factors. Twin and family studies have yielded strong correlations between levels of bone mass and a number of genetic factors. The genes involved could regulate metabolism, formation and resorption of bone, all processes that determine bone mass. We tested 192 sibling pairs of adult Japanese women from 136 families for genetic linkage between osteopenia and allelic variants of four candidate genes (interleukin-6, interleukin-6 receptor, calcium-sensing receptor, and matrix gla protein) using qualitative and quantitative methods, and using as genetic markers dinucleotide-repeat polymorphisms present in or near each of those loci. The interleukin-6 locus showed evidence of linkage to osteopenia analyzed as a qualitative trait, with mean allele sharing of 0.40 (P=0.0001) in discordant pairs and 0.55 (P=0.04) in concordant affected pairs. Variation at this locus was also linked to decreased bone mineral density measured as a quantitative trait (P=0.02). Analyses limited only to the post-menopausal women showed similar or even stronger results. No other locus among those tested showed any evidence of linkage by either method. The results provided strong evidence that genetic variation at the interleukin-6 locus affects regulation of bone mineral metabolism and confers risk for osteopenia and osteoporosis in adult women.     

Insulin-like growth factor-binding proteins and bone metabolism

Insulin-like growth factor-binding proteins (IGFBPs) are important regulators of bone metabolism. However, their precise roles are not fully understood, since IGFBPs can have both enhancing and inhibiting effects on IGF action, depending on context and posttranslational modifications, as well as IGF-independent effects. This review focuses on recent findings from cell culture, rodent models, and clinical studies concerning local IGFBP-2, IGFBP-4, and IGFBP-5 action in bone.     

Combined analysis of transcriptome and proteome data as a tool for the identification of candidate biomarkers in renal cell carcinoma

Results obtained from expression profilings of renal cell carcinoma using different “ome”‐based approaches and comprehensive data analysis demonstrated that proteome‐based technologies and cDNA microarray analyses complement each other during the discovery phase for disease‐related candidate biomarkers. The integration of the respective data revealed the uniqueness and complementarities of the different technologies. While comparative cDNA microarray analyses though restricted to up‐regulated targets largely revealed genes involved in controlling gene/protein expression (19%) and signal transduction processes (13%), proteomics/PROTEOMEX‐defined candidate biomarkers include enzymes of the cellular metabolism (36%), transport proteins (12%), and cell motility/structural molecules (10%). Candidate biomarkers defined by proteomics and PROTEOMEX are frequently shared, whereas the sharing rate between cDNA microarray and proteome‐based profilings is limited. Putative candidate biomarkers provide insights into their cellular (dys)function and their diagnostic/prognostic value but still warrant further validation in larger patient numbers. Based on the fact that merely three candidate biomarkers were shared by all applied technologies, namely annexin A4, tubulin α‐1A chain, and ubiquitin carboxyl‐terminal hydrolase L1, the analysis at a single hierarchical level of biological regulation seems to provide only limited results thus emphasizing the importance and benefit of performing rather combinatorial screenings which can complement the standard clinical predictors.     

Omega-3 polyunsaturated fatty acids and skeletal health

This minireview on skeletal biology describes the actions of prostaglandins and cytokines involved in the local regulation of bone metabolism, it documents the role of lipids in bone biology, and it presents relationships between fatty acids and other factors that impact skeletal metabolism. The data presented herein show consistent and reproducible beneficial effects of omega-3 (n-3) fatty acids on bone metabolism and bone/joint diseases. Polyunsaturated fatty acids modulate eicosanoid biosynthesis in numerous tissues and cell types, alter signal transduction, and influence gene expression. These effects have not been explored in the skeletal system. Future research on n-3 fatty acids in bone biology should focus on the following two aspects. First, the further elucidation of how n-3 fatty acids alter biochemical and molecular processes involved in bone modeling and bone cell differentiation, and second, the evaluation of the potential pharmaceutical applications of these nutraceutical fatty acids in maintaining bone mineral status and controlling inflammatory bone/joint diseases.     

Dynamic alteration of soluble serum biomarkers in healthy aging

Dysbalanced production of inflammatory cytokines is involved in immunosenescence in aging. The age-related changes of the levels of circulating inflammatory mediators and their clinical importance have not been investigated until recently. Still, little is known about the influence of aging on circulating levels of many cytokines, chemokines, growth factors, and angiogenic factors. In the present study, we evaluated the effect of aging on 30 different serum biomarkers involved in pro- and anti-inflammatory responses using multianalyte LabMAP Luminex technology. The simultaneous measurement of serological markers has been done in 397 healthy subjects between 40 and 80 years old. We demonstrated an increase in serum interferon-gamma-inducible chemokines (MIG and IP-10), eotaxin, chemoattractant for eosinophils, and soluble TNFR-II with advancing age. Serum levels of EGFR and EGF, important regulators of cell growth and differentiation, were decreased with age in healthy donors. These data suggest novel pathways, which may be involved in age-associated immunosenescence.     

Copy number variation in CNP267 region may be associated with hip bone size

Osteoporotic hip fracture (HF) is a serious global public health problem associated with high morbidity and mortality. Hip bone size (BS) has been identified as one of key measurable risk factors for HF, independent of bone mineral density (BMD). Hip BS is highly genetically determined, but genetic factors underlying BS variation are still poorly defined. Here, we performed an initial genome-wide copy number variation (CNV) association analysis for hip BS in 1,627 Chinese Han subjects using Affymetrix GeneChip Human Mapping SNP 6.0 Array and a follow-up replicate study in 2,286 unrelated US Caucasians sample. We found that a copy number polymorphism (CNP267) located at chromosome 2q12.2 was significantly associated with hip BS in both initial Chinese and replicate Caucasian samples with p values of 4.73E-03 and 5.66E-03, respectively. An important candidate gene, four and a half LIM domains 2 (FHL2), was detected at the downstream of CNP267, which plays important roles in bone metabolism by binding to several bone formation regulator, such as insulin-like growth factor-binding protein 5 (IGFBP-5) and androgen receptor (AR). Our findings suggest that CNP267 region may be associated with hip BS which might influence the FHL2 gene downstream.     

Circulating levels of insulin-like growth factor-I and -II,and IGF-binding protein-3 in inflammation and after parathyroid hormone infusion

In order to assess if the anabolic action of PTH is related to changes in circulating levels of insulin-like growth factor-I and -II (IGF-I and -II), and IGF binding protein 3 (IGFBP-3), 24 h of PTH infusion was performed in healthy women and in patients with rheumatoid arthritis (RA), a state where both bone metabolism and PTH secretion is influenced by the inflammatory activity. The patients with RA had lower basal levels of both IGF-I and -II than the healthy controls (P < 0.05). In neither group did the IGFs change after 24 h of PTH administration, while IGFBP-3 was significantly increased in the healthy controls (4600 ± 1200 to 5750 ± 2200 μg/l, P < 0.05). IGFBP-3 was not affected by PTH infusion in patients with RA when the disease had high activity, but when inflammation had subsided they responded with a similar increase in IGFBP-3 as the control group and basal IGF-I and -II levels were normalised. Since IGFBP-3 can enhance the anabolic action of IGF-I, increased IGFBP-3 levels after PTH infusion may reflect a mechanism by which PTH is anabolic for bone. Inflammation may inhibit bone formation via decreased serum levels of IGFs and blocked IGFBP-3 response to PTH.     

Genetic diversity in cytokines associated with immune variation and resistance to multiple pathogens in a natural rodent population

Pathogens are believed to drive genetic diversity at host loci involved in immunity to infectious disease. To date, studies exploring the genetic basis of pathogen resistance in the wild have focussed almost exclusively on genes of the Major Histocompatibility Complex (MHC); the role of genetic variation elsewhere in the genome as a basis for variation in pathogen resistance has rarely been explored in natural populations. Cytokines are signalling molecules with a role in many immunological and physiological processes. Here we use a natural population of field voles (Microtus agrestis) to examine how genetic diversity at a suite of cytokine and other immune loci impacts the immune response phenotype and resistance to several endemic pathogen species. By using linear models to first control for a range of non-genetic factors, we demonstrate strong effects of genetic variation at cytokine loci both on host immunological parameters and on resistance to multiple pathogens. These effects were primarily localized to three cytokine genes (Interleukin 1 beta (Il1b), Il2, and Il12b), rather than to other cytokines tested, or to membrane-bound, non-cytokine immune loci. The observed genetic effects were as great as for other intrinsic factors such as sex and body weight. Our results demonstrate that genetic diversity at cytokine loci is a novel and important source of individual variation in immune function and pathogen resistance in natural populations. The products of these loci are therefore likely to affect interactions between pathogens and help determine survival and reproductive success in natural populations. Our study also highlights the utility of wild rodents as a model of ecological immunology, to better understand the causes and consequences of variation in immune function in natural populations including humans.     

Comparing the MicroRNA Spectrum between Serum and Plasma

MicroRNAs (miRNAs) are small, non-coding RNAs that regulate various biological processes, primarily through interaction with messenger RNAs. The levels of specific, circulating miRNAs in blood have been shown to associate with various pathological conditions including cancers. These miRNAs have great potential as biomarkers for various pathophysiological conditions. In this study we focused on different sample types' effects on the spectrum of circulating miRNA in blood. Using serum and corresponding plasma samples from the same individuals, we observed higher miRNA concentrations in serum samples compared to the corresponding plasma samples. The difference between serum and plasma miRNA concentration showed some associations with miRNA from platelets, which may indicate that the coagulation process may affect the spectrum of extracellular miRNA in blood. Several miRNAs also showed platform dependent variations in measurements. Our results suggest that there are a number of factors that might affect the measurement of circulating miRNA concentration. Caution must be taken when comparing miRNA data generated from different sample types or measurement platforms.