A Polymorphism in the Chitotriosidase Gene Associated with Risk of Mycetoma Due to Madurella mycetomatis Mycetoma–A Retrospective Study

Background Madurella mycetomatis is the most prevalent causative agent of eumycetoma in Sudan, an infection characterized by the formation of grains. Many patients are exposed to the causative agent, however only a small number develop infection. M. mycetomatis contains chitin in its cell wall, which can trigger the human immune system. Polymorphisms in the genes encoding for the chitin-degrading enzymes chitotriosidase and AMCase were described, resulting in altered chitinase activity. We investigated the association between 4 of these polymorphisms and the incidence of M. mycetomatis mycetoma in a Sudanese population.MethodologyPolymorphisms studied in 112 eumycetoma patients and 103 matched controls included a 24-bp insertion in the chitotriosidase gene (rs3831317), resulting in impaired chitinase activity and single nucleotide polymorphism (SNP) in the AMCase gene (rs61756687), resulting in decreased AMCase activity. Also, a SNP (rs41282492) and a 10-bp insertion in the 5’UTR region of the AMCase gene (rs143789088) were studied, both resulting in increased AMCase activity. DNA was isolated from blood and genotypes were determined using PCR-RFLP.ConclusionDecreased chitotriosidase activity was associated with increased risk of M. mycetomatis mycetoma.     

Neutrophils as a Source of Chitinases and Chitinase-Like Proteins in Type 2 Diabetes

Purpose

The pathophysiological role of human chitinases and chitinase-like proteins (CLPs) is not fully understood. We aimed to determine the levels of neutrophil-derived chitotriosidase (CHIT1), acidic mammalian chitinase (AMCase) and chitinase 3-like protein 1 (YKL-40) in patients with type 2 diabetes (T2D) and verify their association with metabolic and clinical conditions of these patients.

Methods

Neutrophils were obtained from the whole blood by gradient density centrifugation from 94 T2D patients and 40 control subjects. The activities of CHIT1 and AMCase as well as leukocyte elastase (LE) were measured fluorometrically and concentration of YKL-40 immunoenzymatically. Also, routine laboratory parameters in serum/plasma were determined by standard methods.

Results

The levels of all three examined proteins were about 2-times higher in diabetic patients in comparison to control subjects. They were significantly correlated with the activity of LE and increased progressively across tertiles of LE activity. Moreover, the activities of CHIT1 and AMCase were significantly correlated with each other. Metabolic compensation of diabetes did not influence the levels of these proteins. In the subgroup of patients with inflammatory evidence only YKL-40 concentration was significantly higher compared to those without inflammation. The highest levels of all three proteins were observed in patients with macroangiopathies. Insulin therapy was associated with lower levels of examined proteins.

Conclusions

We revealed that neutrophils may be an important source of the increased levels of chitinases and CLPs in T2D, and these proteins may participate in inflammatory mechanisms in the course of the disease and consequent development of diabetic angiopathies.     

Evaluation of AMCase and CHIT-1 expression in monocyte macrophages lineage

Acidic mammalian chitinase (AMCase) and chitotriosidase (CHIT-1) are two active chitinases expressed in humans. The chitinase activity of AMCase was found to be causative in allergic inflammation and its expression was found to be induced by interleukin-13. CHIT1-1 is expressed by phagocytic cells and extremely high levels are seen in lysosomal storage diseases. Despite that AMCase expression in the inflammation is under investigation, little is known regarding its regulation during macrophages' full maturation and polarization. In this study, we compared AMCase and CHIT-1 modulation during monocyte to macrophage transition and polarization. Gene expression analysis was investigated by real-time PCR from mRNA of human monocytes obtained from buffy coat of healthy volunteers, from mRNA of polarized to classically activated macrophages (or M1), obtained by interferon (IFN)-γ and lipopolysaccharide (LPS) treatment, and from mRNA of alternatively activated macrophages (or M2) obtained by interleukin (IL)-4 exposure. Our results showed that the expression of AMCase and CHIT-1 were differently modulated in HMMs at different stage of maturation. The behavior of these two active chitinase suggests that in the immune response their role is complementary.     

X-Ray Crystal Structure of the Full Length Human Chitotriosidase (CHIT1) Reveals Features of Its Chitin Binding Domain

Chitinases are enzymes that catalyze the hydrolysis of chitin. Human chitotriosidase (CHIT1) is one of the two active human chitinases, involved in the innate immune response and highly expressed in a variety of diseases. CHIT1 is composed of a catalytic domain linked by a hinge to its chitin binding domain (ChBD). This latter domain belongs to the carbohydrate-binding module family 14 (CBM14 family) and facilitates binding to chitin. So far, the available crystal structures of the human chitinase CHIT1 and the Acidic Mammalian Chitinase (AMCase) comprise only their catalytic domain. Here, we report a crystallization strategy combining cross-seeding and micro-seeding cycles which allowed us to obtain the first crystal structure of the full length CHIT1 (CHIT1-FL) at 1.95 Å resolution. The CHIT1 chitin binding domain (ChBD_CHIT1) structure shows a distorted β-sandwich 3D fold, typical of CBM14 family members. Accordingly, ChBD_CHIT1 presents six conserved cysteine residues forming three disulfide bridges and several exposed aromatic residues that probably are involved in chitin binding, including the highly conserved Trp465 in a surface- exposed conformation. Furthermore, ChBD_CHIT1 presents a positively charged surface which may be involved in electrostatic interactions. Our data highlight the strong structural conservation of CBM14 family members and uncover the structural similarity between the human ChBD_CHIT1, tachycitin and house mite dust allergens. Overall, our new CHIT1-FL structure, determined with an adapted crystallization approach, is one of the few complete bi-modular chitinase structures available and reveals the structural features of a human CBM14 domain.     

Nicotinic acetylcholine receptor variants are related to smoking habits, but not directly to COPD

Genome-wide association studies identified single nucleotide polymorphisms (SNPs) in the nicotinic acetylcholine receptors (nAChRs) cluster as a risk factor for nicotine dependency and COPD. We investigated whether SNPs in the nAChR cluster are associated with smoking habits and lung function decline, and if these potential associations are independent of each other. The SNPs rs569207, rs1051730 and rs8034191 in the nAChR cluster were analyzed in the Vlagtwedde-Vlaardingen cohort (n = 1,390) that was followed for 25 years. We used GEE and LME models to analyze the associations of the SNPs with quitting or restarting smoking and with the annual FEV(1) decline respectively. Individuals homozygote (CC) for rs569207 were more likely to quit smoking (OR (95%CI) = 1.58 (1.05-2.38)) compared to wild-type (TT) individuals. Individuals homozygote (TT) for rs1051730 were less likely to quit smoking (0.64 (0.42; 0.97)) compared to wild-type (CC) individuals. None of the SNPs was significantly associated with the annual FEV(1) decline in smokers and ex-smokers. We show that SNPs in the nAChR region are associated with smoking habits such as quitting smoking, but have no significant effect on the annual FEV(1) decline in smokers and ex-smokers, suggesting a potential role of these SNPs in COPD development via smoking habits rather than via direct effects on lung function.     

Toll-Like Receptor (TLR2 and TLR4) Polymorphisms and Chronic Obstructive Pulmonary Disease

Toll-like receptors (TLRs) participate in the defence against bacterial infections that are common in patients with Chronic Obstructive Pulmonary Disease (COPD). We studied all tagging SNPs in TLR2 and TLR4 and their associations with the level and change over time of both FEV(1) and sputum inflammatory cells in moderate-to-severe COPD. Nine TLR2 SNPs and 17 TLR4 SNPs were genotyped in 110 COPD patients. Associations of SNPs with lung function and inflammatory cells in induced sputum were analyzed cross-sectionally with linear regression and longitudinally with linear mixed-effect models. Two SNPs in TLR2 (rs1898830 and rs11938228) were associated with a lower level of FEV(1) and accelerated decline of FEV(1) and higher numbers of sputum inflammatory cells. None of the TLR4 SNPs was associated with FEV(1) level. Eleven out of 17 SNPs were associated with FEV(1) decline, including rs12377632 and rs10759931, which were additionally associated with higher numbers of sputum inflammatory cells at baseline and with increase over time. This is the first longitudinal study showing that tagging SNPs in TLR2 and TLR4 are associated with the level and decline of lung function as well as with inflammatory cell numbers in induced sputum in COPD patients, suggesting a role in the severity and progression of COPD.     

Marked differences in tissue-specific expression of chitinases in mouse and man.

Two distinct chitinases have been identified in mammals: a phagocyte-specific enzyme named chitotriosidase and an acidic mammalian chitinase (AMCase) expressed in the lungs and gastrointestinal tract. Increased expression of both chitinases has been observed in different pathological conditions: chitotriosidase in lysosomal lipid storage disorders like Gaucher disease and AMCase in asthmatic lung disease. Recently, it was reported that AMCase activity is involved in the pathogenesis of asthma in an induced mouse model. Inhibition of chitinase activity was found to alleviate the inflammation-driven pathology. We studied the tissue-specific expression of both chitinases in mice and compared it to the situation in man. In both species AMCase is expressed in alveolar macrophages and in the gastrointestinal tract. In mice, chitotriosidase is expressed only in the gastrointestinal tract, the tongue, fore-stomach, and Paneth cells in the small intestine, whereas in man the enzyme is expressed exclusively by professional phagocytes. This species difference seems to be mediated by distinct promoter usage. In conclusion, the pattern of expression of chitinases in the lung differs between mouse and man. The implications for the development of anti-asthma drugs with chitinases as targets are discussed.     

Quantification of Chitinase mRNA Levels in Human and Mouse Tissues by Real-Time PCR: Species-Specific Expression of Acidic Mammalian Chitinase in Stomach Tissues

Chitinase hydrolyzes chitin, which is an N-acetyl-D-glucosamine polymer that is present in a wide range of organisms, including insects, parasites and fungi. Although mammals do not contain any endogenous chitin, humans and mice express two active chitinases, chitotriosidase (Chit1) and acidic mammalian chitinase (AMCase). Because the level of expression of these chitinases is increased in many inflammatory conditions, including Gaucher disease and mouse models of asthma, both chitinases may play important roles in the pathophysiologies of these and other diseases. We recently established a quantitative PCR system using a single standard DNA and showed that AMCase mRNA is synthesized at extraordinarily high levels in mouse stomach tissues. In this study, we applied this methodology to the quantification of chitinase mRNAs in human tissues and found that both chitinase mRNAs were widely expressed in normal human tissues. Chit1 mRNA was highly expressed in the human lung, whereas AMCase mRNA was not overexpressed in normal human stomach tissues. The levels of these mRNAs in human tissues were significantly lower than the levels of housekeeping genes. Because the AMCase expression levels were quite different between the human and mouse stomach tissues, we developed a quantitative PCR system to compare the mRNA levels between human and mouse tissues using a human-mouse hybrid standard DNA. Our analysis showed that Chit1 mRNA is expressed at similar levels in normal human and mouse lung. In contrast, the AMCase expression level in human stomach was significantly lower than that expression level observed in mouse stomach. These mRNA differences between human and mouse stomach tissues were reflecting differences in the chitinolytic activities and levels of protein expression. Thus, the expression level of the AMCase in the stomach is species-specific.     

Triad of polar residues implicated in pH specificity of acidic mammalian chitinase

Acidic mammalian chitinase (AMCase) is a mammalian chitinase that has been implicated in allergic asthma. One of only two active mammalian chinases, AMCase, is distinguished from other chitinases by several unique features. Here, we present the novel structure of the AMCase catalytic domain, both in the apo form and in complex with the inhibitor methylallosamidin, determined to high resolution by X‐ray crystallography. These results provide a structural basis for understanding some of the unique characteristics of this enzyme, including the low pH optimum and the preference for the β‐anomer of the substrate. A triad of polar residues in the second‐shell is found to modulate the highly conserved chitinase active site. As a novel target for asthma therapy, structural details of AMCase activity will help guide the future design of specific and potent AMCase inhibitors.     

DNMT3A rs36012910 A>G polymorphism and gastric cancer susceptibility in a Chinese population

DNA-methyltransferase (DNMT)-3A plays a crucial role in embryonic development and aberrant DNA methylation in carcinogenesis. Polymorphisms of the DNMT3A gene may influence its enzymatic activity and its contribution to susceptibility to cancer. This study evaluated the association of DNMT3A rs36012910 A>G with susceptibility to gastric cancer (GC) in a Chinese population. Genomic DNA was extracted from samples taken from 340 patients with GC and 251 healthy control subjects. The genotype frequency of DNMT3A rs36012910 A>G in all subjects was detected by polymerase chain reaction–restriction fragment length polymorphism and confirmed by sequencing. Stratification analyses were used to study subgroups by age and gender and to evaluate the association of rs36012910 A>G polymorphism with genetic susceptibility to GC. All patients and control individuals were successfully genotyped for the DNMT3A rs36012910 A>G polymorphism. The frequency of DNMT3A rs36012910 allele G is 3.39?% in healthy individuals and 7.78?% in GC patients, respectively. The rs36012910 AG genotype was significantly more common in the GC group than in the controls, although the rs36012910 GG genotype was only one case in GC patients. Further stratification indicated that AG+GG genotypes were associated with susceptibility to GC in males older than 60, but this polymorphism has no significant association with GC susceptibility in females. Male individuals who carried AG+GG genotypes had a 2.362-fold increased risk of GC compared to those who carried the AA genotype. The rs36012910 allele G was associated with an increased risk of GC compared to the rs36012910 allele A. This is the first report to investigate the distribution and evaluate the association of a rare SNP in DNMT3A with genetic susceptibility to GC. DNMT3A rs36012910 A>G might become a potential biomarker for use in GC prediction, although further studies in larger groups and different populations are needed for confirmation.     

Replication study of PLCE1 and C20orf54 polymorphism and risk of esophageal cancer in a Chinese population

Esophageal cancer is one of the most aggressive cancers in the world. Recent large-scale genome-wide association studies (GWAS) reported that functional genetic variations in the phospholipase C epsilon gene (PLCE1) were strongly associated with risk of esophageal squamous cell carcinoma (ESCC) and gastric cardia adenocarcinoma (GCA) in Chinese population. For C20orf54 rs13042395 genotype and risk of esophageal cancer, the results were inconsistent. We conducted a replication case-control study to evaluate the genetic effects of these two functional single nucleotide polymorphisms (SNPs) on the development of esophageal cancer. A total of 380 cases and 380 controls were recruited for this study. The genotypes were determined by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS). The variant alleles of the functional polymorphism, PLCE1 rs2274223 SNP was associated with the increased risk of esophageal cancer [adjusted odds ratio (OR) = 1.95, 95 % confidence interval (CI) = 1.05-3.59 for PLCE1 rs2274223 GG vs. AA]. However, there was no significant association between the C20orf54 rs13042395 genotype and esophageal cancer risk (adjusted OR = 0.99, 95 % CI = 0.63-1.57 for C20orf54 rs13042395 TT vs. CC). Stratified analyses indicated a significantly increased risk of esophageal cancer associated with the PLCE1 rs2274223 AG genotype was more evident among females, younger patients and never drinkers, compared with the PLCE1 rs2274223 AA genotypes. Stratified analyses also indicated a significantly increased risk of esophageal cancer associated with the PLCE1 rs2274223 GG genotype was more evident among never smokers and never drinkers compared with the PLCE1 rs2274223 AA genotypes. These findings indicated that functional polymorphisms PLCE1 rs2274223 might contribute to esophageal cancer susceptibility.     

Identification of a novel duplication CFTRdup2 and functional impact of large rearrangements identified in the CFTR gene

The aim of this study was to investigate associations of two candidate gene SNPs of the endocannabinoid receptor type 1 gene (CNR1) with overweight, obesity and obesity-related traits in Chinese retired women. The study subjects were a subsample of the Taizhou Retiree Women Cohort, consisting of 2812 retired women aged 50-64 years recruited from Taizhou, Jiangsu, China. Neither rs2023239 nor rs806381 polymorphism was significantly associated with body mass index-defined overweight and obesity or waist-to-hip-ratio-defined obesity. For obesity-related traits, rs2023239 was significantly associated with glutamate pyruvate transaminase (GPT) (median, 18.00 vs 17.00 for TT and TC genotypes, respectively, P=0.043). The rs806381 also showed significant association with triglyceride (TG) (mean±SD, 1.46±0.20 vs 1.53±0.20 for GA and GG+AA genotypes, respectively, P=0.013) under the dominant genetic model. In conclusion, the rs2023239 and rs806381 polymorphisms of CNR1 were not associated with increased overweight and obesity risk. But the rs2023239 polymorphism was significantly associated with GPT, and the rs806381 polymorphism was significantly associated with TG.     

rs11567842 SNP in <Emphasis Type="Italic">SLC13A2</Emphasis> gene associates with hypocitraturia in Thai patients with nephrolithiasis

Hypocitraturia is a profound risk for kidney stone formation and recurrence. Sodium-dicarboxylate cotransporter-1 (NaDC-1) is a main transporter responsible for citrate reabsorption in renal proximal tubules. To investigate an association of sodium-dicarboxylate cotransporter-1 (NaDC-1) polymorphism with hypocitraturia in Thai patients with nephrolithiasis (NL). Exonic SNPs in NaDC-1 were screened in peripheral blood DNA of 13 NL patients. The rs11567842 (A/G) variant was found and further genotyped in 145 NL patients and 115 non-stone forming controls. NL patients had significantly lower level of urinary citrate than the controls. Based on logistic regression, hypocitraturia was significantly associated with urinary stone formation (adjusted OR 8.34, 95% CI 4.63–15.04). Significant association of urinary citrate level with rs11567842 genotype was found only in the NL group. NL patients with GG genotype had significantly higher urinary citrate than those with AA and AG genotypes. GG carrying patients had significantly reduced risk for hypocitraturia (adjusted OR 0.15; 95% CI 0.05–0.48, AA as reference). In selected 15 calcium oxalate stone patients, AA carriers had significantly higher intrarenal NaDC-1 mRNA than GG and AG carriers. Homozygous GG of rs11567842 SNP in NaDC-1 gene was a protective genotype for hypocitraturia in kidney stone patients. The findings suggested that patients with AA genotypes were more susceptible to hypocitraturia than those with GG, hence carrying a higher risk for kidney stone recurrence.     

Association Between Single Nucleotide Polymorphisms of DOT1L Gene and Risk of Knee Osteoarthritis in a Chinese Han Population

To investigate associations between single nucleotide polymorphisms rs12982744 and rs12459350 in the DOT1L gene and knee osteoarthritis (OA) susceptibility in a Chinese Han population. DOT1L rs12982744 and rs12459350 polymorphisms were genotyped in patients with knee OA and age- and sex-matched OA-free controls from a Chinese Han population. A total of 605 patients with knee OA and 615 controls were enrolled in the study. GC and CC genotypes of rs12982744, and variant C, were associated with a significantly increased risk of knee OA. On stratification analysis, the association between the risk of OA and rs12982744 GC heterozygotes compared with GG homozygotes was stronger in females and those aged >65 years. In contrast, the GA and AA genotypes of rs12459350 were not significantly associated with the risk of knee OA, even after further stratification analysis according to age or sex. Our results showed that DOT1L rs12982744 G to C change and variant C genotype may contribute to knee OA risk in a Chinese Han population.     

Retracted: Rs11655237 polymorphism of LINC00673 affects the prognosis of cervical cancer by interfering with the interaction between LINC00673 and microRNA-1231

Single-nucleotide polymorphism (SNP) in long noncoding RNAs (lncRNAs) is known to disrupt the binding between lncRNAs and microRNAs. In this paper, we aimed to explore the role of LINC00673 rs11655237 SNP in the survival of cervical cancer (CC). Real-time polymerase chain reaction and western-blot analysis were used to detect expressions of LINC00673 and microRNA-1231 (miR-1231) in CC patients with different rs11655237 SNP genotypes. And the expression of LINC00673, miR-1231, and IFNAR1 was measured in mice and cells treated with exosomes carrying GG, GA, and AA rs11655237 genotypes. Compared with patients carrying the rs11655237 A allele of LINC00673 rs11655237 SNP, patients carrying the G allele showed higher overall survival and higher miR-1231 expression. In addition, the expression of miR-1231 was the highest in patients carrying the GG genotype and the lowest in patients carrying the AA genotype. Furthermore, the exosomes carrying GG, GA, and AA genotypes of LINC00673 rs11655237 SNP reduced tumor growth in mice, while the inhibitory effect of rs11655237 A allele was much stronger than that of the rs11655237 G allele. Additionally, exosome treatment upregulated the expression of LINC000673 and IFNAR1 while downregulating the expression of miR-1231. Interestingly, the A allele of rs11655237 generated a binding site for miR-1231 and subsequently affected the expression of IFNAR1, a target gene of miR-1231 containing a miR-1231 binding site in its 3′-untranslated region. Cells transfected with exosomes carrying GG, GA, and AA genotypes of LINC00673 rs11655237 SNP achieved higher LINC000673 and IFNAR1 expression along with lower miR-1231 expression. Therefore, rs11655237 can be used as a prognostic biomarker for CC.     

在青岛汉族人群中INSIG1rs9769826单核苷酸多态性与血糖水平有关,与血脂水平无关（英文）

目的：探讨青岛汉族人群中INSIG1rs9769826单核苷酸多态性与血糖和血脂的关系。方法：随机选取217名年龄在35-86岁健康的青岛汉族居民作为受试者。应用聚合酶链式反应-限制片段长度多态性检测技术（PCR-RFLP）对INSIG1基因rs9769826多态性进行基因分型,用协方差分析的方法分析rs9769826多态性与血糖和血脂的关系。结果：INSIG1基因rs9769826位点AAAG GG基因型的频率分别为70.04%,36.73%和3.23%,INSIG1基因rs9769826多态性与空腹血糖水平之间差异有显著意义（P〈0.001）,与血脂水平差异无显著意义。结论：INSIGIrs9769826突变基因G与空腹血糖升高有关。     

Leukocyte Telomere Length-Related rs621559 and rs398652 Genetic Variants Influence Risk of HBV-Related Hepatocellular Carcinoma

Recent genome-wide association studies (GWAS) have identified eleven leukocyte telomere length (LTL)-related single nucleotide polymorphisms (SNPs). Since LTL has been associated with risk of many malignancies, LTL-related SNPs may contribute to cancer susceptibility. To test this hypothesis in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC), we genotyped these eleven LTL-related SNPs in a case-control set including 1186 HBV-related HCC cases, 508 chronic HBV carriers and 1308 healthy controls at the discovery stage. The associations of HCC risk with these SNPs were further confirmed in an independent case-control set. We found that 1p34.2 rs621559 and 14q21 rs398652 were significantly associated with HBV-related HCC risk (both P<0.005 after Bonferroni corrections). There was no significant difference of either rs621559 or rs398652 genotypes between chronic HBV carriers and healthy controls, demonstrating that the association was not due to predisposition to HBV infection. In the pooled analyses (1806 HBV-related HCC cases and 1954 controls), we observed a decreased HCC risk, 0.72-times, associated with the 1p34.2 rs621559 AA genotype compared to the GG genotype (P = 1.6×10⁻⁶). Additionally, there was an increased HCC risk, 1.27-fold, associated with the rs398652 GG genotype (P = 3.3×10⁻⁶). A statistical joint effect between the rs621559 GG and rs398652 GG genotypes may exist in elevating risk of HBV-related HCC. We show, for the first time, that rs398652 and rs621559 might be marker genetic variants for risk of HBV-related HCC in the Chinese population.