Circulating Calprotectin as a Biomarker of COVID-19 Severity.

INTRODUCTION: Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Although demographic and clinical parameters such as sex, age, comorbidities, genetic background and various biomarkers have been identified as risk factors, there is an unmet need to predict the risk and onset of severe inflammatory disease leading to poor clinical outcomes. In addition, very few mechanistic biomarkers are available to inform targeted treatment of severe (auto)-inflammatory conditions associated with COVID-19. Calprotectin, also known as S100A8/S100A9, MRP8/14 (Myeloid-Related Protein) or L1, is a heterodimer involved in neutrophil-related inflammatory processes. In COVID-19 patients, calprotectin levels were reported to be associated with poor clinical outcomes such as significantly reduced survival time, especially in patients with severe pulmonary disease. AREAS COVERED: Pubmed was searched using the following keywords: Calprotectin + COVID19, S100A8/A9 + COVID19, S100A8 + COVID-19, S100A9 + COVID-19, MRP8/14 + COVID19; L1 + COVID-19 between May 2020 and 8 March 2021. The results summarized in this review provide supporting evidence and propose future directions that define calprotectin as an important biomarker in COVID-19. EXPERT OPINION: Calprotectin represents a promising serological biomarker for the risk assessment of COVID-19 patients.

Increased expressions of cellular ATP-binding cassette transporters may be a promising diagnostic marker for colorectal cancer.

OBJECTIVES: To measure the blood expression levels of related drug-resistant ATP-binding cassette (ABC) transporters in colorectal cancer (CRC) patients and to assess these examined transporters for whether they present signi cant expression in connection with the tumor appearance of CRC. METHODS: In this case-control study, the messenger ribonucleic acids were isolated from the blood of 62 CRC patients who were recruited from King Abdulaziz University Hospital Oncology Clinic and 46 controls from King Fahad General Hospital Blood Bank (Jeddah, Saudi Arabia) from September 2016 to March 2017. The Biomedical Ethics Unit at King Abdulaziz University, Jeddah, Saudi Arabia approved this study. The expressions of ABC transporters were measured using quantitative polymerase chain reaction. GraphPad Prism 5 and REST 2009 Software were used to correlate the expressions with clinicopathological independent stages and body mass index. A p-value of less than 0.05 was considered significant. RESULTS: The results showed that the 3 ABC transporters, particularly ABCC1 (p less than 0.0001), were highly expressed in the blood of CRC patients compared with controls. However, none of the 3 transporters was related to the progression of CRC, age, gender, or body mass index. CONCLUSION: The expressions of ABC transporters were found to be significantly higher in CRC patients, and they may act as diagnostic markers and should potentially be tested for their contribution to drug sensitivity in CRC patients.

Expression quantitative trait loci in ABC transporters are associated with survival in 5-FU treated colorectal cancer patients.

The chemotherapeutic efficacy in colorectal cancer (CRC) is limited due to the inter-individual variability in drug response and the development of tumour resistance. ATP-binding cassette (ABC) transporters are crucial in the development of resistance by the efflux of anticancer agents from cancer cells. In this study, we identified 14 single nucleotide polymorphisms (SNPs) in 11 ABC transporter genes acting as an expression of quantitative trait loci (eQTLs), i.e. whose variation influence the expression of many downstream genes. These SNPs were genotyped in a case-control study comprising 1098 cases and 1442 healthy controls and analysed in relation to CRC development risk and patient survival. Considering a strict correction for multiple tests, we did not observe any significant association between SNPs and CRC risk. The rs3819720 polymorphism in the ABCB3/TAP2 gene was statistically significantly associated with shorter overall survival (OS) in the codominant, and dominant models [GA vs. GG, hazard ratio (HR) = 1.48; P = 0.002; AA vs. GG, HR = 1.70; P = 0.004 and GA + AA vs. GG, HR = 1.52; P = 0.0006]. Additionally, GA carriers of the same SNP displayed worse OS after receiving 5-FU based chemotherapy. The variant allele of rs3819720 polymorphism statistically significantly affected the expression of 36 downstream genes. Screening for eQTL polymorphisms in relevant genes such as ABC transporters that can regulate the expression of several other genes may help to identify the genetic background involved in the individual response to the treatment of CRC patients.

Nilotinib interferes with cell cycle, ABC transporters and JAK-STAT signaling pathway in CD34+/lin- cells of patients with chronic phase chronic myeloid leukemia after 12 months of treatment.

Chronic myeloid leukemia (CML) is characterized by the constitutive tyrosine kinase activity of the oncoprotein BCR-ABL1 in myeloid progenitor cells that activates multiple signal transduction pathways leading to the leukemic phenotype. The tyrosine-kinase inhibitor (TKI) nilotinib inhibits the tyrosine kinase activity of BCR-ABL1 in CML patients. Despite the success of nilotinib treatment in patients with chronic-phase (CP) CML, a population of Philadelphia-positive (Ph+) quiescent stem cells escapes the drug activity and can lead to drug resistance. The molecular mechanism by which these quiescent cells remain insensitive is poorly understood. The aim of this study was to compare the gene expression profiling (GEP) of bone marrow (BM) CD34+/lin- cells from CP-CML patients at diagnosis and after 12 months of nilotinib treatment by microarray, in order to identify gene expression changes and the dysregulation of pathways due to nilotinib action. We selected BM CD34+/lin- cells from 78 CP-CML patients at diagnosis and after 12 months of first-line nilotinib therapy and microarray analysis was performed. GEP bioinformatic analyses identified 2,959 differently expressed probes and functional clustering determined some significantly enriched pathways between diagnosis and 12 months of nilotinib treatment. Among these pathways, we observed the under expression of 26 genes encoding proteins belonging to the cell cycle after 12 months of nilotinib treatment which led to the up-regulation of chromosome replication, cell proliferation, DNA replication, and DNA damage checkpoint at diagnosis. We demonstrated the under expression of the ATP-binding cassette (ABC) transporters ABCC4, ABCC5, and ABCD3 encoding proteins which pumped drugs out of the cells after 12 months of nilotinib. Moreover, GEP data demonstrated the deregulation of genes involved in the JAK-STAT signaling pathway. The down-regulation of JAK2, IL7, STAM, PIK3CA, PTPN11, RAF1, and SOS1 key genes after 12 months of nilotinib could demonstrate the up-regulation of cell cycle, proliferation and differentiation via MAPK and PI3K-AKT signaling pathways at diagnosis.

Clinical Significance of Myeloid-Related Protein 8/14 as a Predictor for Biological Treatment and Disease Activity in Rheumatoid Arthritis.

OBJECTIVES: To investigate the serum level of Myeloid-Related Protein 8/14 complex (MRP8/14) and to predict and monitor the response to biologic treatment in rheumatoid arthritis (RA) patients. METHODS: Each patient underwent clinical examination and blood sampling for assessment of serum high-sensitivity C-reactive protein (hs-CRP) levels, erythrocyte sedimentation rate (ESR), rheumatoid factors (RF), anti-cyclic citrullinated protein antibodies (anti-CCP), and serum concentrations of MRP8/14 protein complexes (myeloid-related proteins, MRP8/14) were measured at baseline, and weeks 4 and 12 (after initiation of treatment). RESULTS: Serum MRP8/14 protein complex levels correlated with DAS28 and anti-CCP antibody. MRP8/14 protein complex levels decreased significantly after 12 weeks treatment with biological therapy: mono-rhTNFR-Fc active group. rhTNFR-Fc plus methotrexate (MTX) decreased MRP8/14 protein complex levels from 11839±1849 ng/ml to 5423±1130 ng/ml (p<0.01) a reduction of 54.2% compared with 32.9% in the rhTNFR-Fc group. CONCLUSIONS: MRP8/14 protein complex levels were increased in active stage RA patients. MRP8/14 levels were decreased with rhTNFR-Fc treatment, suggesting serum concentrations of MRP8/14 protein complex might be a promising biomarker to predict responses to biological therapy in active RA patients at baseline and could be used to monitor responses to treatment across different mechanisms of action.

7-Ketocholesterol is increased in the plasma of X-ALD patients and induces peroxisomal modifications in microglial cells: Potential roles of 7-ketocholesterol in the pathophysiology of X-ALD.

X-linked adrenoleukodystrophy (X-ALD) is a genetic disorder induced by a mutation in the ABCD1 gene, which causes the accumulation of very long-chain fatty acids in tissue and plasma. Oxidative stress may be a hallmark of X-ALD. In the plasma of X-ALD patients with different forms of the disease, characterized by high levels of C24:0 and C26:0, we observed the presence of oxidative stress revealed by decreased levels of GSH, α-tocopherol, and docosahexaenoic acid (DHA). We showed that oxidative stress caused the oxidation of cholesterol and linoleic acid, leading to the formation of cholesterol oxide derivatives oxidized at C7 (7-ketocholesterol (7KC), 7ß-hydroxycholesterol (7ß-OHC), and 7α-hydroxycholesrol (7α-OHC)) and of 9- and 13-hydroxyoctadecadienoic acids (9-HODE, 13-HODE), respectively. High levels of 7KC, 7ß-OHC, 7α-OHC, 9-HODE and 13-HODE were found. As 7KC induces oxidative stress, inflammation and cell death, which could play key roles in the development of X-ALD, the impact of 7KC on the peroxisomal status was determined in microglial BV-2 cells. Indeed, environmental stress factors such as 7KC could exacerbate peroxisomal dysfunctions in microglial cells and thus determine the progression of the disease. 7KC induces oxiapoptophagy in BV-2 cells: overproduction of H2O2 and O2-, presence of cleaved caspase-3 and PARP, nuclear condensation and/or fragmentation; elevated [LC3-II/LC3-I] ratio, increased p62 levels. 7KC also induces several peroxisomal modifications: decreased Abcd1, Abcd2, Abcd3, Acox1 and/or Mfp2 mRNA and protein levels, increased catalase activity and decreased Acox1-activity. However, the Pex14 level was unchanged. It is suggested that high levels of 7KC in X-ALD patients could foster generalized peroxisomal dysfunction in microglial cells, which could in turn intensify brain damage.

Serum myeloid-related protein 8/14 in minimal change- and glomerulonephritis-related nephrotic syndrome.

BACKGROUND: Myeloid-related protein 8/14 (MRP8/14) forms stable heterodimers and is the major calcium-binding protein secreted by activated granulocytes and monocytes. We evaluated whether serum MRP8/14 level is a useful indicator for a differential diagnosis of glomerulonephritis (GN)- and minimal change disease (MC)- related nephrotic syndrome (NS). METHODS: Serum MRP8/14 complex was evaluated in 37 NS patients with MC or GN. These patients were divided into two groups. Group 1 consisted of 13 NS patients with MC, and group 2 consisted of 24 NS patients with GN. Group 2 was further divided into four subgroups: IgA nephropathy (IgAN; n = 5), Henoch-Schönlein purpura nephritis (HSPN; n = 6), focal segmental glomerulosclerosis (FSGS; n = 12), and acute GN Poststreptococcal acute glomeruloNephritis (PSAGN; n = 1). RESULTS: The clinical manifestations, laboratory findings, serum MRP8/14 level, and renal accumulation of MRP8 were investigated for each group. No significant inter-group differences were observed for serum total protein, serum albumin, or blood urea nitrogen and urinary protein excretions. Mean serum MRP8/14 in the IgAN, HSPN, FSGS, and PSAGN groups was higher than in group 1. Further, the mean glomerular and interstitial MRP8 staining scores in the IgAN, HSPN, and PSAGN groups were higher than in group 1. CONCLUSIONS: Serum MRP8/14 level may be a useful indicator for differential diagnosis between GN- and MC- related NS.

Chemotherapy Agents Alter Plasma Lipids in Breast Cancer Patients and Show Differential Effects on Lipid Metabolism Genes in Liver Cells.

Cardiovascular complications have emerged as a major concern for cancer patients. Many chemotherapy agents are cardiotoxic and some appear to also alter lipid profiles, although the mechanism for this is unknown. We studied plasma lipid levels in 12 breast cancer patients throughout their chemotherapy. Patients received either four cycles of doxorubicin and cyclophosphamide followed by weekly paclitaxel or three cycles of epirubicin, cyclophosphamide and 5'-fluorouracil followed by three cycles of docetaxel. Patients demonstrated a significant reduction (0.32 mmol/L) in high density lipoprotein cholesterol (HDL-C) and apolipoprotein A1 (apoA1) levels (0.18 g/L) and an elevation in apolipoprotein B (apoB) levels (0.15 g/L) after treatment. Investigation of the individual chemotherapy agents for their effect on genes involved in lipoprotein metabolism in liver cells showed that doxorubicin decreased ATP binding cassette transporter A1 (ABCA1) via a downregulation of the peroxisomal proliferator activated receptor γ (PPARγ) and liver X receptor α (LXRα) transcription factors. In contrast, ABCA1 levels were not affected by cyclophosphamide or paclitaxel. Likewise, apoA1 levels were reduced by doxorubicin and remained unaffected by cyclophosphamide and paclitaxel. Doxorubicin and paclitaxel both increased apoB protein levels and paclitaxel also decreased low density lipoprotein receptor (LDLR) protein levels. These findings correlate with the observed reduction in HDL-C and apoA1 and increase in apoB levels seen in these patients. The unfavourable lipid profiles produced by some chemotherapy agents may be detrimental in the longer term to cancer patients, especially those already at risk of cardiovascular disease (CVD). This knowledge may be useful in tailoring effective follow-up care plans for cancer survivors.

Myeloid-related proteins-8 and -14 are expressed but dispensable in the pathogenesis of experimental epidermolysis bullosa acquisita and bullous pemphigoid.

BACKGROUND: Myeloid-related protein-8 (MRP-8) and its heterodimeric partner, MRP-14 belong to the group of danger-associated molecular patterns (DAMPs) and are associated with numerous chronic human disorders. However, their functional role in autoimmunity remains largely unclear. OBJECTIVE: Here, we examined the involvement of MRP-8/-14 in two difficult-to-treat autoimmune blistering diseases, epidermolysis bullosa acquisita (EBA) and bullous pemphigoid (BP). METHODS: MRP-8/-14 concentrations in the sera of EBA and BP patients were quantified by ELISA. Experimental EBA and BP in mice were induced by transfer of antibodies directed against type VII or XVII collagen, respectively. Expression of MRP-8/-14 was analyzed in skin samples of these experimental mouse models. The functional role of MRP-8/-14 proteins was evaluated by the induction of experimental EBA and BP in MRP-14-deficient mice. RESULTS: We found serum levels of MRP-8/-14 to be elevated in both, EBA and BP patients. Furthermore, in the lesional skin of mice with experimental diseases expression of MRP-8/-14 was increased as compared to healthy controls. However, MRP-14-deficient mice were fully susceptible to experimental disease with a phenotype comparable to that of wild type controls. CONCLUSION: Although MRP-8/-14 expression is highly increased in experimental as well as human disease, these proteins do not contribute to the pathogenesis in the effector phase of EBA and BP.

Elevated expressions of myeloid-related proteins-8 and -14 are danger biomarkers for lupus nephritis.

Myeloid-related proteins, MRP-8 and -14, which have been identified as molecules that mediate the danger signaling in innate immune response, are also known as the DAMPs (damage associated molecular pattern molecules). The proteins were found in infiltrating macrophages and neutrophils at inflammatory sites. Their expression was correlated with severe forms of glomerulonephritis. Therefore, this study examined whether or not MRP-8 and -14 can be used as biomarkers for identifying severely active lupus nephritis (LN). Total blood leukocyte samples and renal biopsy tissues from a prospective cohort of LN patients were used to determine mRNA and protein expression levels of MRP-8 and -14. The mRNA levels of MRP-8 and -14 in total blood leukocytes were significantly higher in active LN patients than quiescent LN patients and healthy controls. Moreover, the mRNA levels of MRP-8 and -14 in the total blood leukocytes and kidney tissues were significantly correlated with therapeutic response and the mRNA expression levels in the kidney were associated with an early loss of the kidney function. MRP-8 and -14 can be used as non-invasive prognostic biomarkers in patients with LN.

Distinct Plasma Bile Acid Profiles of Biliary Atresia and Neonatal Hepatitis Syndrome.

Biliary atresia (BA) is a severe chronic cholestasis disorder of infants that leads to death if not treated on time. Neonatal hepatitis syndrome (NHS) is another leading cause of neonatal cholestasis confounding the diagnosis of BA. Recent studies indicate that altered bile acid metabolism is closely associated with liver injury and cholestasis. In this study, we systematically measured the bile acid metabolome in plasma of BA, NHS, and healthy controls. Liver bile acids were also measured using biopsy samples from 48 BA and 16 NHS infants undergoing operative cholangiography as well as 5 normal adjacent nontumor liver tissues taken from hepatoblastoma patients as controls. Both BA and NHS samples had significantly elevated bile acid levels in plasma compared to normal controls. BA patients showed a distinct bile acid profile characterized by the higher taurochenodeoxycholic acid (TCDCA) level and lower chenodeoxycholic acid (CDCA) level than those in NHS patients. The ratio of TCDCA to CDCA in plasma was significantly higher in BA compared to healthy infants (p < 0.001) or NHS (p < 0.001). The area under receiver operating characteristic curve for TCDCA/CDCA to differentiate BA from NHS was 0.923 (95% CI: 0.862-0.984). These findings were supported by significantly altered expression levels of bile acid transporters and nuclear receptors in liver including farnesoid X receptor (FXR), small heterodimer partner (SHP), bile salt export pump (BSEP), and multidrug resistant protein 3 (MDR3) in BA compared to NHS. Taken together, the plasma bile acid profiles are distinct in BA, NHS, and normal infants, as characterized by the ratio of TCDCA/CDCA differentially distributed among the three groups of infants.

MRP8/14 serum levels as a predictor of response to starting and stopping anti-TNF treatment in juvenile idiopathic arthritis.

INTRODUCTION: Approximately 30% of juvenile idiopathic arthritis (JIA) patients fail to respond to anti-TNF treatment. When clinical remission is induced, some patients relapse after treatment has been stopped. We tested the predictive value of MRP8/14 serum levels to identify responders to treatment and relapse after discontinuation of therapy. METHODS: Samples from 88 non-systemic JIA patients who started and 26 patients who discontinued TNF-blockers were analyzed. MRP8/14 serum levels were measured by in-house MRP8/14 ELISA and by Bühlmann Calprotectin ELISA at start of anti-TNF treatment, within 6 months after start and at discontinuation of etanercept in clinical remission. Patients were categorized into responders (ACRpedi ≥ 50 and/or inactive disease) and non-responders (ACRpedi < 50) within six months after start, response was evaluated by change in JADAS-10. Disease activity was assessed within six months after discontinuation. RESULTS: Baseline MRP8/14 levels were higher in responders (median MRP8/14 of 1466 ng/ml (IQR 1045-3170)) compared to non-responders (median MRP8/14 of 812 (IQR 570-1178), p < 0.001). Levels decreased after start of treatment only in responders (p < 0.001). Change in JADAS-10 was correlated with baseline MRP8/14 levels (Spearman's rho 0.361, p = 0.001). Patients who flared within 6 months after treatment discontinuation had higher MRP8/14 levels (p = 0.031, median 1025 ng/ml (IQR 588-1288)) compared to patients with stable remission (505 ng/ml (IQR 346-778)). Results were confirmed by Bühlmann ELISA with high reproducibility but different overall levels. CONCLUSION: High levels of baseline MRP8/14 are associated with good response to anti-TNF treatment, whereas elevated MRP8/14 levels at discontinuation of etanercept are associated with higher chance to flare.

Prognostic value of circulating CD133(+) cells in patients with gastric cancer.

OBJECTIVES: Gastric cancer is an important cause of cancer-related mortality worldwide (1). There is increasing evidence that the existence of cancer stem cells (CSC) is responsible for tumour formation and maintenance. MATERIALS AND METHODS: The present study was designed to recognise circulating CSCs from blood samples of patients with gastric cancer, using CD133 and ABCG2 as potential markers. CD133(-) , CD133(+)  ABCG2(-) and CD133(+)  ABCG2(+) cells lines were analysed by flow cytometry, immunofluorescence staining, western blotting and real-time PCR. Furthermore, functional assays (clonogenic assay in vitro and tumourigenic assay in vivo) were also performed using these cell lines. RESULTS: Higher percentages of CD133(+) cells were identified in blood samples from gastric cancer patients compared to normal controls. In addition, we found by using Kaplan-Meier analysis, that numbers of CD133(+) cells correlated with poor prognosis gastric cancer patients. Finally, tumourigenic properties of CD133(+)  ABCG2(+) cells were determined in vitro and in vivo. CONCLUSIONS: Our in vitro and in vivo experiments demonstrated that CD133(+)  ABCG2(+) cells exhibited well-known CSC characteristics; thus when circulating they could be used as a prognostic marker for gastric cancer.

MRP8/14 serum levels as a strong predictor of response to biological treatments in patients with rheumatoid arthritis.

BACKGROUND: One-third of rheumatoid arthritis (RA) patients treated with biological therapy show lack of response. The use of predictive biomarkers to identify responders to treatment may provide guidance in optimising treatment strategies and reduce unnecessary side effects and costs. OBJECTIVE: To test the ability of myeloid-related proteins (MRP)8/14 protein complexes, an endogenous TLR-4 receptor agonist, to predict and monitor response to biologics in RA patients. METHODS: 170 RA patients treated with adalimumab (n=86), infliximab (n=60) or rituximab (n=24) were categorised into clinical responders (n=123) and non-responders (n=47). MRP8/14 serum complexes were measured at baseline, and 4 and 16 weeks after initiation of treatment and related to response outcome. RESULTS: Before initiation of treatment, responders showed significantly higher MRP8/14 protein complex levels compared with non-responders in each prospective cohort (p=0.010, p=0.001 and p<0.001, respectively). Logistic regression analysis showed that having high MRP8/14 baseline levels increased the odds of being a responder by 3.3 up to 55. In responders to adalimumab or infliximab treatment, MRP8/14 levels decreased after 4 weeks of treatment by 46% and 60% and after 16 weeks by 61% and 68%, respectively. In contrast, MRP8/14 levels were stable in non-responders. In patients treated with rituximab, MRP8/14 levels decreased by 59% after 16 weeks in responders and increased by 89% after 16 weeks in non-responders. CONCLUSION: Serum concentrations of MRP8/14 protein complex are a promising biomarker to predict response to biological therapy in active RA patients at baseline and could be used to monitor response to treatment across different mechanisms of action.

Chlorogenic acid protects against atherosclerosis in ApoE-/- mice and promotes cholesterol efflux from RAW264.7 macrophages.

Chlorogenic acid (CGA) is one of the most abundant polyphenols in the human diet and is suggested to be a potential antiatherosclerotic agent due to its proposed hypolipidemic, anti-inflammatory and antioxidative properties. The aim of this study was to evaluate the effect of CGA on atherosclerosis development in ApoE(-/-) mice and its potential mechanism. ApoE(-/-) mice were fed a cholesterol-rich diet without (control) or with CGA (200 and 400 mg/kg) or atorvastatin (4 mg/kg) for 12 weeks. During the study plasma lipid and inflammatory parameters were determined. Treatment with CGA (400 mg/kg) reduced atherosclerotic lesion area and vascular dilatation in the aortic root, comparable to atorvastatin. CGA (400 mg/kg) also significantly decreased plasma levels of total cholesterol, triglycerides and low-density lipoprotein-cholesterol as well as inflammatory markers. Supplementation with CGA or CGA metabolites-containing serum suppressed oxidized low-density lipoprotein (oxLDL)-induced lipid accumulation and stimulated cholesterol efflux from RAW264.7 cells. CGA significantly increased the mRNA levels of PPARγ, LXRα, ABCA1 and ABCG1 as well as the transcriptional activity of PPARγ. Cholesterol efflux assay showed that three major metabolites, caffeic, ferulic and gallic acids, significantly stimulated cholesterol efflux from RAW264.7 cells. These results suggest that CGA potently reduces atherosclerosis development in ApoE(-/-) mice and promotes cholesterol efflux from RAW264.7 macrophages. Caffeic, ferulic and gallic acids may be the potential active compounds accounting for the in vivo effect of CGA.

Metabolic syndrome, alcohol consumption and genetic factors are associated with serum uric acid concentration.

OBJECTIVE: Uric acid is the end product of purine metabolism in humans, and increased serum uric acid concentrations lead to gout. The objective of the current study was to identify factors that are independently associated with serum uric acid concentrations in a cohort of Czech control individuals. METHODS: The cohort consisted of 589 healthy subjects aged 18-65 years. We studied the associations between the serum uric acid concentration and the following: (i) demographic, anthropometric and other variables previously reported to be associated with serum uric acid concentrations; (ii) the presence of metabolic syndrome and the levels of metabolic syndrome components; and (iii) selected genetic variants of the MTHFR (c.665C>T, c.1286A>C), SLC2A9 (c.844G>A, c.881G>A) and ABCG2 genes (c.421C>A). A backward model selection procedure was used to build two multiple linear regression models; in the second model, the number of metabolic syndrome criteria that were met replaced the metabolic syndrome-related variables. RESULTS: The models had coefficients of determination of 0.59 and 0.53. The serum uric acid concentration strongly correlated with conventional determinants including male sex, and with metabolic syndrome-related variables. In the simplified second model, the serum uric acid concentration positively correlated with the number of metabolic syndrome criteria that were met, and this model retained the explanatory power of the first model. Moderate wine drinking did not increase serum uric acid concentrations, and the urate transporter ABCG2, unlike MTHFR, was a genetic determinant of serum uric acid concentrations. CONCLUSION: Metabolic syndrome, moderate wine drinking and the c.421C>A variant in the ABCG gene are independently associated with the serum uric acid concentration. Our model indicates that uric acid should be clinically monitored in persons with metabolic syndrome.

Epipolymorphisms within lipoprotein genes contribute independently to plasma lipid levels in familial hypercholesterolemia.

Gene polymorphisms associated so far with plasma lipid concentrations explain only a fraction of their heritability, which can reach up to 60%. Recent studies suggest that epigenetic modifications (DNA methylation) could contribute to explain part of this missing heritability. We therefore assessed whether the DNA methylation of key lipoprotein metabolism genes is associated with high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglyceride levels in patients with familial hypercholesterolemia (FH). Untreated FH patients (61 men and 37 women) were recruited for the measurement of blood DNA methylation levels at the ABCG1, LIPC, PLTP and SCARB1 gene loci using bisulfite pyrosequencing. ABCG1, LIPC and PLTP DNA methylation was significantly associated with HDL-C, LDL-C and triglyceride levels in a sex-specific manner (all P<0.05). FH subjects with previous history of coronary artery disease (CAD) had higher LIPC DNA methylation levels compared with FH subjects without CAD (P = 0.02). Sex-specific multivariable linear regression models showed that new and previously reported epipolymorphisms (ABCG1-CpGC3, LIPC-CpGA2, mean PLTP-CpGC, LPL-CpGA3, CETP-CpGA2, and CETP-CpGB2) significantly contribute to variations in plasma lipid levels (all P<0.001 in men and P<0.02 in women), independently of traditional predictors such as age, waist circumference, blood pressure, fasting plasma lipids and glucose levels. These results suggest that epigenetic perturbations of key lipoprotein metabolism genes are associated with plasma lipid levels, contribute to the interindividual variability and might partially explain the missing heritability of plasma lipid levels, at least in FH.

Defining the Jr(a-) phenotype in the Japanese population.

BACKGROUND: The Jr(a-) phenotype is rare in European and North American populations but is not so rare in Japanese and other Asian populations. Recently, two groups have established the connection between the Jr(a-) phenotype and the ATP-binding cassette, member G2 (ABCG2) gene and concluded that ABCG2-null alleles encode the Jr(a-) phenotype. In Japanese Red Cross Blood Centers, the Jr(a-) phenotype is found with a prevalence of 0.05% among blood donors, and we applied DNA-based genotyping to investigate the molecular basis of the Jr(a-) phenotype in Japan, in addition to serologic typing. STUDY DESIGN AND METHODS: Purified genomic DNA extracts of Japanese donor samples [500 Jr(a+) and 85 Jr(a-) phenotypes] were amplified using specific amplification primers for the c.376C>T mutation, which is the most common mutation in the Asian JRnull allele. Polymerase chain reaction products were examined by high-resolution melt techniques and DNA sequence analyses. RESULTS: Seventy-nine of 85 Jr(a-) samples were homozygous for the single-nucleotide polymorphism c.376C>T (Gln126Stop) change. In other samples, two novel null alleles were detected: c.2T>C and c.421C>A: c.1515delC. CONCLUSION: In this study, more than 90% of the Japanese Jr(a-) phenotypes had c.376C>T (Gln126Stop) nucleotide change. In the other Jr(a-), a new mutation (c.2T>C) in the start codon encoding Thr instead of Met, c.1515delC encoding Ala505AlafsStop and heterozygous for c.337C/T and c.736C/T were detected. DNA-based genotyping is accurate and useful for Jr(a-) donor typing.