The DEFB1 gene rs11362 A/G genetic variant is associated with risk of developing CAD: a case-control study

BACKGROUND

In the present study, we evaluated whether DEFB1 gene polymorphisms are associated with the presence of coronary artery disease (CAD).

METHODS

Two rs11362 A/G, and rs1800972 C/G gene polymorphisms of DEFB1 gene were genotyped by 5'exonuclease TaqMan assays in 219 patients with CAD and 522 control individuals.

RESULTS

The distribution of rs1800972 C/G polymorphisms was similar in patients with CAD and healthy controls. Nonetheless, under the co-dominant, dominant, recessive, and additive models, the AA genotype of the rs11362 A/G polymorphism was associated with the risk of developing CAD (OR = 1.89 pCCo-Dom = 0.041, OR = 1.46, pCDom = 0.034, OR = 1.69, pCRes = 0.039, and OR = 1.37, pCAdd = 0.012, respectively). In addition, the linkage disequilibrium showed that the 'AG' haplotype was associated with an increased risk of developing CAD (OR = 1.23, p = 0.042). According, with the Genotype-Tissue Expression (GTEx) consortium data, the rs11362 AA genotype is associated with a low mRNA expression of the β-defensin-1 in tissues, such as artery aorta, artery coronary, heart left ventricle, and heart atrial appendage (p < 0.001).

CONCLUSION

This study demonstrates that rs11362 A/G polymorphism of the DEFB1 gene is involved in the risk of developing CAD, and with a low RNA expression of the β-defensin-1 in heart tissue.

Relationship between biofilm-forming microorganisms (BFM: Staphylococcus aureus and Pseudomonas aeruginosa) and DEFB1 gene variants on β-defensin levels in periprosthetic joint infection (PJI)

BACKGROUND

The purpose of this study was to investigate the relationship between biofilm-forming microorganisms (BFM) and DEFB1 gene variants on β-defensin levels in patients with periprosthetic joint infection (PJI) of Mexican origin.

METHODS AND RESULTS

One hundred and five clinical aspirates were obtained from patients with suspected PJI. After microbiologic culture, samples were classified as non-septic and septic; of the latter, only those positive for Staphylococcus aureus and Pseudomonas aeruginosa were selected. β-Defensin levels were quantified by ELISA, DNA was extracted from total leukocytes of the samples, and - 20G > A (rs11362) and - 44 C > G (rs1800972) variants were genotyped using TaqMan probes. Forty-one clinical aspirates were non-septic, 18 were positive for S. aureus and 18 were positive for P. aeruginosa. It was observed that β-defensin levels were higher in the P. aeruginosa group compared to S. aureus group (2339.0 pg/mL IQR = 1809.2 vs. 1821.3 pg/mL IQR = 1536.4) and non-septic group (2339.0 pg/mL IQR = 1809.2 vs. 1099.7 pg/mL IQR = 1744.5, P < 0.001). The CG genotype of the rs1800972 variant was associated with higher β-defensin levels compared to the CC genotype for both P. aeruginosa and S. aureus (1905.8 vs. 421.7 pg/mL, P = 0.004; and 1878.2 vs. 256.4 pg/mL, P = 0.006, respectively).

CONCLUSIONS

Our results show that β-defensin levels are significantly elevated in patients with BFM-associated PJI compared to those without infection. Furthermore, carriers of the CG genotype of the rs1800972 variant have an increased risk of PJI. Further research is needed to replicate these findings in a larger population.

Human beta-defensin 1 circulating level and gene polymorphism in non-segmental vitiligo Egyptian patients

BACKGROUND

Vitiligo is an acquired depigmented skin disorder. It has a genetic and autoimmune background. Human beta defensin-1(HBD-1) plus its gene polymorphism were linked to some autoimmune disorders.

OBJECTIVE

To elucidate the possible role of HBD-1 in the pathogenesis of non-segmental vitiligo (NSV) through evaluation of HBD-1 serum levels and its single nucleotide polymorphism (SNP) in patients having NSV, in addition, to correlating the results with the extent of vitiligo in those patients.

METHODS

A current case-control study included 50 patients having NSV and 50 controls. The authors used Vitiligo Area Scoring Index (VASI) score to assess vitiligo severity and laboratory investigations to assess serum HBD-1 level using ELISA and defensin-beta1 (DEFB1) SNP using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS

There were significantly lower HBD-1 serum levels in NSV cases than in controls (p < 0.001). There was a significant predominance of GG DEFB1 genotype and G allele in NSV patients in comparison to controls (p < 0.001). The levels of serum HBD-1 and DEFB1 genotypes were not associated or correlated significantly with any of the personal and clinical parameters of vitiligo patients.

STUDY LIMITATION

The small sample size.

CONCLUSIONS

DEFB1 gene polymorphism (GG genotype and G allele) may modulate vitiligo risk and contribute to vitiligo development in Egyptian populations. Decreased circulating HBD-1 levels might have an active role in vitiligo etiopathogenesis that could be mediated through its possible anti-inflammatory effects.

Identification of Novel Disease-Relevant Genes and Pathways in the Pathogenesis of Type 1 Diabetes: A Potential Defect in Pancreatic Iron Homeostasis

Multiple pathways contribute to the pathophysiological development of type 1 diabetes (T1D); however, the exact mechanisms involved are unclear. We performed differential gene expression analysis in pancreatic islets of NOD mice versus age-matched congenic NOD.B10 controls to identify genes that may contribute to disease pathogenesis. Novel genes related to extracellular matrix development and glucagon and insulin signaling/secretion were changed in NOD mice during early inflammation. During "respective" insulitis, the expression of genes encoding multiple chemosensory olfactory receptors were upregulated, and during "destructive" insulitis, the expression of genes involved in antimicrobial defense and iron homeostasis were downregulated. Islet inflammation reduced the expression of Hamp that encodes hepcidin. Hepcidin is expressed in β-cells and serves as the key regulator of iron homeostasis. We showed that Hamp and hepcidin levels were lower, while iron levels were higher in the pancreas of 12-week-old NOD versus NOD.B10 mice, suggesting that a loss of iron homeostasis may occur in the islets during the onset of "destructive" insulitis. Interestingly, we showed that the severity of NOD disease correlates with dietary iron intake. NOD mice maintained on low-iron diets had a lower incidence of hyperglycemia, while those maintained on high-iron diets had an earlier onset and higher incidence of disease, suggesting that high iron exposure combined with a loss of pancreatic iron homeostasis may exacerbate NOD disease. This mechanism may explain the link seen between high iron exposure and the increased risk for T1D in humans.

β-defensin 1 Gene Polymorphisms are Associated with Kidney Disease in Northwestern Mexicans with Type 2 Diabetes

Diabetic kidney disease (DKD) is one of the more limiting complications to the quality of life of diabetes mellitus patients. Studies including cultured cells, animal models, and case-control studies highlight the role of human β-defensin-1 (hBD-1) in diabetes.This study assessed the association of hBD-1 gene (DEFB1) functional variations -52 G/A (rs1799946), -44 C/G (rs1800972) and -20 G/A (rs11362) with type 2 diabetes mellitus (T2DM) in order to investigate its effects on genetic susceptibility and progression to DKD in a Mexican population. A total of 214 T2DM patients with and without DKD (n = 102 and n = 112, respectively) and 117 healthy subjects participated in this case-control study. Genotyping was made by PCR-RFLPs. Clinical and biochemical parameters of all patients were measured. There was no statistically significant difference in genotype or allele frequencies between patients and healthy individuals. Nevertheless, compared with patients without DKD, DKD patients have a reduced prevalence of AA genotype of -52 G/A (OR = 0.307, 95% CI = 0.104-0.905, p =.026), as well as a higher frequency of GA genotype of -20 G/A variant (OR = 1.875, 95%CI = 1.031-3.409, p = .038). Our results suggest that rs1799946 and rs11362 could be useful variants to stratify T2DM Mexican patients in order to prescribe closer follow-up to prevent or retard DKD. Further tests in different ethnic groups are encouraged.

DEFB1 gene polymorphisms modify vitiligo extent and response to NB-UVB phototherapy

Human beta defensin-1(hBD-1); an antimicrobial peptide, has immune regulatory effects which may be involved in autoimmunity. The aims were to evaluate the association between defensin beta 1 (DEFB1) (-44 C/G) and (-20 G/A) gene polymorphisms with the risk of vitiligo development, the extent of the disease and the response to NB-UVB treatment in a sample of Egyptian population. 178 active nonsegmental vitiligo patients and 182 control subjects were included in this prospective case control study. Vitiligo extent was evaluated using vitiligo area scoring index (VASI). Gene polymorphisms in all participants were studied by RFLP PCR technique. Patients were treated by three narrowband UVB (NB-UVB) treatment sessions per week. After 12 weeks, the patients were reevaluated clinically to assess the extent of the disease using VASI scoring again and to evaluate the type of repigmentation, if any. AA genotype of DEFB1 (-20G/A) has a protective role against vitiligo development, while (DEFB1 -44 C/G) GG genotype and G allele increase the risk of vitiligo development about two folds. Patients carrying polymorphism in DEFB1 (-20G/A) only showed the lowest VASI scores (14.23 ± 2.77) and the highest percentage of improvement (66.12 ± 18.01%), while patients carrying polymorphism in DEFB1(-44 C/G) only showed the highest baseline VASI scores (38.87 ± 6.7) and the lowest therapeutic response (23.79 ± 19.42%) among all patients groups. Different DEFB1 gene polymorphisms may modify the risk of vitiligo development, the disease extent and the response to NB-UVB phototherapy.

Association of systemic beta-defensin-1 and -20G/A DEFB1 gene polymorphism with Behçet's disease

BACKGROUND

Behçet's disease (BD) is a multisystem inflammatory disease of unknown etiology. Beta-defensins are antimicrobial peptides involved in epithelial host defense. To explore whether beta-defensins might be involved in BD pathogenesis, we examined plasma human beta-defensin-1 (hBD-1) and DEFB1 -20G/A polymorphism in BD patients.

METHODS

This case-control study included 106 BD patients fulfilling the criteria of the International Study Group for BD and 156 controls. The -20G/A genotypes were determined by PCR-RFLP analysis in all participants, and plasma hBD-1 was assessed by ELISA in 77 BD patients and 44 controls, only. Stepwise multiple regression models were applied to determine independent predictors for plasma hBD-1 in BD patients.

RESULTS

Distribution of -20G/A genotypes was different between BD patients and controls. Compared to GG genotype, "GA" genotype [OR (95% CI), 3.12 (1.56-6.16); p = .001] and "AA" genotype [2.57 (1.10-5.96); p = .027)] were associated with increased risk for BD. Plasma hBD-1 concentrations were significantly higher in BD patients than controls (9.81 ± 3.52 ng/mL vs. 5.30 ± 3.02 ng/mL; p < .001), and in BD patients with neurological involvement than those without (11.1 ± 4.12 ng/mL vs. 9.19 ± 3.10 ng/mL; p = .040). No variation was noted according to other clinical features, treatment received or -20G/A genotypes. In multivariate analysis, neurological involvement was the only predictor for plasma hBD-1 (β, 0.274; p = .029).

CONCLUSIONS

Findings suggest that hBD-1 and its encoding gene DEFB1 could modulate the risk for BD, especially for BD neurological involvement. Further work is needed for a better understanding of role of hBD-1 and its genetic variants in the pathogenesis of BD.

The -44 C/G (rs1800972) polymorphism of the β-defensin 1 is associated with increased risk of developing type 2 diabetes mellitus

Background

The aim of this study was to establish the association of two polymorphisms of the β‐defensin 1 gene (DEFB1, OMIM#602056) with the risk of developing type 2 diabetes mellitus (T2DM) in a group of Mexican patients.

Methods

The 5′UTR −20 G/A, and −44 C/G polymorphisms of DEFB1 gene were genotyped by 5′ exonuclease TaqMan assays in a group of 252 patients with T2DM and 522 healthy control.

Results

Under dominant and additive models adjusted for the risk factors, the C allele of the −44 C/G polymorphism was associated with increased risk of T2DM (OR = 1.63, 95% CI = 1.07–2.48, pC_dom = 0.021 and OR = 1.42, 95% CI = 1.05–1.91, pC_add = 0.023, respectively). In addition, the linkage disequilibrium analysis showed that AC haplotype was associated with an increased risk of developing T2DM (OR = 4.39, p = 0.04). The in‐silico analysis showed that the −44 C allele produces a binding site for the transcription factor Ikaros (IK).

Conclusion

This study demonstrates that the C allele of −44 C/G polymorphism, as well as haplotype AC are associated with the presence of T2DM in the Mexican population. The variation in this polymorphism of the DEFB1 gene could increase the migration of the macrophages to pancreatic islets accelerate the β‐cell dysfunction in T2DM.

Prediction of the impact of coding missense and nonsense single nucleotide polymorphisms on HD5 and HBD1 antibacterial activity against Escherichia coli

Defensins confer host defense against microorganisms and are important for human health. Single nucleotide polymorphisms (SNPs) in defensin gene-coding regions could lead to less active variants. Using SNP data available at the dbSNP database and frequency information from the 1000 Genomes Project, two DEFA5 (L26I and R13H) and eight DEFB1 (C35S, K31T, K33R, R29G, V06I, C12Y, Y28* and C05*) missense and nonsense SNPs that are located within mature regions of the coded defensins were retrieved. Such SNPs are rare and population restricted. In order to assess their antibacterial activity against Escherichia coli, two linear regression models were used from a previous work, which models the antibacterial activity as a function of solvation potential energy, using molecular dynamics data. Regarding only the antibacterial predictions, for HD5, no biological differences between wild-type and its variants were observed; while for HBD1, the results suggest that the R29G, K31T, Y28* and C05* variants could be less active than the wild-type one. The data here reported could lead to a substantial improvement in knowledge about the impact of missense SNPs in human defensins and their world distribution. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 633-644, 2016.

DEFB1 gene polymorphisms and tuberculosis in a Northeastern Brazilian population

β-Defensin-1, an antimicrobial peptide encoded by the DEFB1 gene, is known to play an important role in lung mucosal immunity. In our association study we analyzed three DEFB1 functional polymorphisms −52G>A (rs1799946), −44C>G (rs1800972) and −20G>A (rs11362) in 92 tuberculosis patients and 286 healthy controls, both from Northeast Brazil: no association was found between the studied DEFB1 polymorphisms and the disease. However we cannot exclude that this lack of association could be due to the low number of subjects analyzed, as suggested by the low statistical power achieved for the three analyzed SNPs (values between 0.16 and 0.50).

Association between graves' disease and renal coloboma syndrome: a case report

Renal coloboma syndrome is an autosomal dominant condition characterized by renal lesions and optic nerve abnormalities. We report an 11-yr-old Japanese girl with familial renal coloboma syndrome, who also had Graves’ disease. Four affected family members had a previously reported heterozygous mutation (c.76dupG, p.Val26Glyfs*28) in the PAX2 gene. We hypothesized that PAX2 mutations may increase the risk of autoimmune diseases through alterations of human β-defensin 1 expression.

Antimicrobial peptide elicitors: New hope for the post-antibiotic era

Antimicrobial peptides or host defense peptides are fundamental components of human innate immunity. Recent and growing evidence suggests they have a role in a broad range of diseases, including cancer, allergies and susceptibility to infection, including HIV/AIDS. Antimicrobial peptide elicitors (APEs) are physical, biological or chemical agents that boost human antimicrobial peptide expression. The current knowledge of APEs and their potential use in the treatment of human infectious diseases are reviewed, and a classification system for APEs is proposed. The efficient use of APEs in clinical practice could mark the beginning of the urgently needed post-antibiotic era, but further trials assessing their efficacy and safety are required.