Glycosylation of IgG Associates with Hypertension and Type 2 Diabetes Mellitus Comorbidity in the Chinese Muslim Ethnic Minorities and the Han Chinese

Objectives: Hypertension and type 2 diabetes mellitus comorbidity (HDC) is common, which confers a higher risk of cardiovascular disease than the presence of either condition alone. Describing the underlying glycomic changes of immunoglobulin G (IgG) that predispose individuals to HDC may help develop novel protective immune-targeted and anti-inflammatory therapies. Therefore, we investigated glycosylation changes of IgG associated with HDC. Methods: The IgG N-glycan profiles of 883 plasma samples from the three northwestern Chinese Muslim ethnic minorities and the Han Chinese were analyzed by ultra-performance liquid chromatography instrument. Results: We found that 12 and six IgG N-glycan traits showed significant associations with HDC in the Chinese Muslim ethnic minorities and the Han Chinese, respectively, after adjustment for potential confounders and false discovery rate. Adding the IgG N-glycan traits to the baseline models, the area under the receiver operating characteristic curves (AUCs) of the combined models differentiating HDC from hypertension (HTN), type 2 diabetes mellitus (T2DM), and healthy individuals were 0.717, 0.747, and 0.786 in the pooled samples of Chinese Muslim ethnic minorities, and 0.828, 0.689, and 0.901 in the Han Chinese, respectively, showing improved discriminating performance than both the baseline models and the glycan-based models. Conclusion: Altered IgG N-glycan profiles were shown to associate with HDC, suggesting the involvement of inflammatory processes of IgG glycosylation. The alterations of IgG N-glycome, illustrated here for the first time in HDC, demonstrate a biomarker potential, which may shed light on future studies investigating their potential for monitoring or preventing the progression from HTN or T2DM towards HDC.

Glycomics for Type 2 Diabetes Biomarker Discovery: Promise of Immunoglobulin G Subclass-Specific Fragment Crystallizable N-glycosylation in the Uyghur Population

Aberrant immunoglobulin G (IgG) N-glycosylation offers new prospects to detect changes in cell metabolism and by extension, for biomarker discovery in type 2 diabetes mellitus (T2DM). However, past studies did not analyze the individual IgG subclasses in relation to T2DM pathophysiology. We report here original findings through a comparison of the IgG subclass-specific fragment crystallizable (Fc) glycan biosignatures in 115 T2DM patients with 122 healthy controls within the Uyghur population in China. IgG Fc glycosylation profiles were analyzed using nano-liquid chromatography-mass spectrometry to exclude changes attributed to fragment antigen binding N-glycosylation. After correction for clinical covariates, 27 directly measured and 4 derived glycan traits of the IgG subclass-specific N-glycopeptides were significantly associated with T2DM. Furthermore, we observed in T2DM a decrease in bisecting N-acetylglucosamine of IgG2 and agalactosylation of IgG4, and an increase in sialylation of IgG4 and digalactosylation of IgG2. Classification model based on IgG subclass-specific N-glycan traits was able to distinguish patients with T2DM from controls with an area under the receiver operating characteristic curve of 0.927 (95% confidence interval 0.894-0.960, p < 0.001). In conclusion, a robust association between the IgG subclass-specific Fc N-glycomes and T2DM was observed in the Uyghur population sample in China, suggesting a potential for the IgG Fc glycosylation as a biomarker candidate for type 2 diabetes. The integration of glycomics with other system science biomarkers might offer further hope for innovation in diagnosis and treatment of T2DM in the future. Finally, it is noteworthy that "Population Glycomics" is an emerging approach to biomarker discovery for common complex diseases.

The association between subclass-specific IgG Fc N-glycosylation profiles and hypertension in the Uygur, Kazak, Kirgiz, and Tajik populations

Hypertension results from the interaction of genetic and acquired factors. IgG occurs in the form of different subclasses, of which the effector functions show significant variation. The detailed differences between the glycosylation profiles of the individual IgG subclasses may be lost in a profiling method for total IgG N-glycosylation. In this study, subclass-specific IgG Fc glycosylation profile was investigated in the four northwestern Chinese minority populations, namely, Uygur (UIG), Kazak (KZK), Kirgiz (KGZ), and Tajik (TJK), composed of 274 hypertensive patients and 356 healthy controls. The results showed that ten directly measured IgG N-glycan traits (i.e., IgG1G0F, IgG2G0F, IgG2G1FN, IgG2G1FS, IgG2G2S, IgG4G0F, IgG4G1FS, IgG4G1S, IgG4G2FS, and IgG4G2N) representing galactosylation and sialylation are significantly associated with hypertension, with IgG4 consistently showing weaker associations of its sialylation, across the four ethnic groups. We observed a modest improvement on the AUC of ROC curve when the IgG Fc N-glycan traits are added into the glycan-based model (difference between AUCs, 0.044, 95% CI: 0.016-0.072, P = 0.002). The AUC of the diagnostic model indicated that the subclass-specific IgG Fc N-glycan profiles provide more information reinforcing current models utilizing age, gender, BMI, and ethnicity, and demonstrate the potential of subclass-specific IgG Fc N-glycosylation profiles to serve as a biomarker for hypertension. Further research is however required to determine the additive value of subclass-specific IgG Fc N-glycosylation on top of biomarkers, which are currently used.

[A comparative study on characterizations of genetic recombination hotspots in PPARG gene between Kirgiz and Uyghur ethnic groups in Xinjiang]

OBJECTIVE

To investigate the characterizations of genetic recombination hotspots and linkage disequilibrium (LD) patterns in peroxisome proliferative activated receptor gamma (PPARG) gene in Kirgiz and Uyghur ethnic groups.

METHODS

Blood samples were collected from 100 Kirgiz (50 healthy controls and 50 patients with type 2 diabetes mellitus) residents in Halajun County, Artux City, Kizilsu Kirgiz Autonomous Prefecture, Xinjiang in August 2013, and 50 healthy Uyghur residents in Hotan Prefecture of Xinjiang Uygur Autonomous Region in May 2012.Thirty-one tagSNPs in PPARG gene were genotyped using Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF-MS) method.The recombination hotspots and LD patterns within the PPARG gene were estimated by analyzing the SNP genotying data using the Hotspot Fisher program and Haploview software, respectively.

RESULTS

Eighteen tagSNPs (rs1151999, rs1175540, rs1875796, rs1899951, rs2292101, rs2921190, rs2938397, rs2959272, rs2959273, rs2972162, rs3856806, rs4135247, rs4135275, rs709151, rs4135354, rs6805419, rs17036700 and rs4135304) were same with relatively higher recombination rates between the patients with type 2 diabetes mellitus (T2DM) and healthy controls of Kirgiz ethnic group, and healthy controls of Uyghur ethnic group.Five haplotype blocks with LD coefficient D' value of 1, indicating no genetic recombination occurred within the region, were observed in the healthy controls of Kirgiz ethnic groups, whereas five haplotype blocks with LD coefficient D' value less than 1 were observed in the Kirgiz patients with T2DM, indicating historical recombination events occurred within the region.Four haplotype blocks with LD coefficient D' value of 1 were observed in the Uyghur healthy controls, indicating no genetic recombination occurred within the region.There were significantly different recombination hotspot profiles between the Kirgiz, Uyghur, Utah residents with Northern and Western European ancestry (CEU), Yoruban in Ibadan, Nigeria (YRI) and Han Chinese in Beijing (CHB) and Japanese in Tokyo (JPT) samples.There are six recombination hotspots in the HapMap profile of genetic recombination.The last 5 SNPs within the PPARG gene were shown with lower recombination rates in the Kirgiz, whereas no recombination hotspot was found in the Uyghur.

CONCLUSIONS

Variable recombination rates may be present in certain chromosome region between patients and healthy controls within the same or between the different ethnic groups.There may be presence of recombination hotspots of ethnic specificity and with variable recombination rates.

The Uyghur population and genetic susceptibility to type 2 diabetes: potential role for variants in CDKAL1, JAZF1, and IGF1 genes

Substantial evidence suggests that type 2 diabetes mellitus (T2DM) is a multi-factorial disease with a strong genetic component. A list of genetic susceptibility loci in populations of European and Asian ancestry has been established in the literature. Little is known on the inter-ethnic contribution of such established functional polymorphic variants. We performed a case-control study to explore the genetic susceptibility of 16 selected T2DM-related SNPs in a cohort of 102 Uyghur objects (51 cases and 51 controls). Three of the 16 SNPs showed significant association with T2DM in the Uyghur population. There were significant differences between the T2DM and control groups in frequencies of the risk allelic distributions of rs7754840 (CDKAL1) (p=0.014), rs864745 (JAZF1) (p=0.032), and rs35767 (IGF1) (p=0.044). Carriers of rs7754840-C, rs35767-A, and rs864745-C risk alleles had a 2.32-fold [OR (95% CI): 1.19-4.54], 2.06-fold [OR (95% CI): 1.02-4.17], 0.48-fold [OR (95% CI): 0.24-0.94] increased risk for T2DM, respectively. The cumulative risk allelic scores of these 16 SNPs differed significantly between the T2DM patients and the controls [17.1±8.1 vs. 15.4±7.3; OR (95%CI): 1.27(1.07-1.50), p=0.007]. This is the first study to evaluate genomic variation at 16 SNPs in respective T2DM candidate genes for the Uyghur population compared with other ethnic groups. The SNP rs7754840 in CDKAL1, rs864745 in JAZF1, and rs35767 in IGF1 might serve as potential susceptibility loci for T2DM in Uyghurs. We suggest a broader capture and study of the world populations, including who that are hitherto understudied, are essential for a comprehensive understanding of the genetic/genomic basis of T2DM.

[Study of cytochrome P450 1A1 gene 3'-UTR 6235T-C polymorphism and susceptibility to breast cancer with Uighur medicine]

OBJECTIVE

To explore the association between polymorphism of cytochrome P450 1A1 Gene 3'-UTR (3'-untranslated region) 6235T-C and breast cancer with abnormal Hilit in Chinese Han population of Xinjiang.

METHODS

The breast cancer patients were divided into four body fluids according to Uighur medical theories. And the technique of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was employed to detect the genotypic and allelic frequencies of 6235T-C polymorphism situated in 3'-untranslated region of CYP1A1 gene in 137 breast cancer patients with abnormal Hilit and 148 normal control subjects in Han population of Xinjiang province.

RESULTS

(1) Significant differences in the genotypic and allelic distribution frequencies of CYP1A1 gene 3'-UTR6235T-C were found between breast cancer patients with abnormal Sapra Hilit and controls (χ(2) = 8.790, P = 0.012; χ(2) = 7.102, P = 0.008). The frequencies of CC genotype and C allele were significantly higher in breast cancer patients with abnormal Sapra Hilit (16.4% vs 39.8%) than in controls (4.7% vs 25.7%). (2) Significant differences in the genotypes and allelic distribution frequencies of CYP1A1 gene 3'-UTR6235T-C were found between breast cancer patients with abnormal Savda Hilit and controls (χ(2) = 6.638, P = 0.036; χ(2) = 5.824, P = 0.016). And the frequencies of TC, CC genotypes and C allele were significantly higher in breast cancer patients with abnormal Savda Hilit (56.9%, 9.8%, 39.2%) than those of the controls (41.9%, 4.7%, 25.7%).

CONCLUSION

The CC genotype and C allele of 6235T-C polymorphism of CYP1A1 may be linked with breast cancer with abnormal Sapra Hilit and abnormal savda Hilit in Chinese Han population of Xinjiang province. But they are not correlated with the susceptibility to breast cancer with abnormal Balgham Hilit.

[Association analysis between polymorphism of dopamine transporter variable number tandem repeat and breast cancer with abnormal Hilit]

OBJECTIVE

To explore the association between polymorphism of dopamine 1 transporter variable number tandem repeat (DAT1 VNTR) and breast cancer with abnormal Hilit in Chinese Han population from Xinjiang.

METHODS

The breast caner patients were divided into four body fluids according to Uighur medicine theory. And polymerase chain reaction and VNTR polymorphism technique were employed to detect genotypic and allelic frequencies of a 40 bp VNTR polymorphism situated in 3' untranslated region of DAT1 gene in 144 breast cancer patients with abnormal Hilit and 104 normal control subjects in Han population of Xinjiang province.

RESULTS

In our sample, the repeat numbers of 40 bp were 7 and 9 - 11 (PCR product length of 360 bp and 440 bp to 520 bp) and 10-repeat allele (480 bp) detected was the dominant allele of DAT1 gene polymorphisms with an allelic frequency of 90.9%; Seven kinds of genotype were detected and genotype 10/10 was the most common genotype with a genotypic frequency of 83.1%. The frequency of 10-repeats allele and 10/10 genotype was significantly higher in breast caner patients with abnormal balgham Hilit than in controls (OR = 0.127, 95%CI 0.016 - 0.988, P = 0.026; OR = 0.134, 95%CI 0.018 - 1.016, P = 0.020) and breast caner patients with abnormal Sapra Hilit (OR = 0.132, 95%CI 0.016 - 1.075, P = 0.049; OR = 0.132, 95%CI 0.017 - 1.042, P = 0.033).

CONCLUSION

The 10-repeats allele and 10/10 genotype of 40 bp VNTR polymorphism of DAT1 may increase the risk of breast cancer with Uighur medicine abnormal Hilit in Chinese Han population from Xinjiang province and it is not correlated with the susceptibility to breast cancer with Uighur medicine abnormal Sapra Hilit.