TGF-β1 and TSC-22 Gene Polymorphisms and Susceptibility to Microvascular Complications in Type 2 Diabetes

The rs1800469 T/T and rs1800470 C/C genotypes of the TGFB1 gene confer protection against diabetic retinopathy in a Southern Brazilian population

The transforming growth factor beta 1 (TGFB1) is a pro-inflammatory cytokine that plays a key role in the mechanisms of angiogenesis and breakdown of the blood-retina barrier, which are implicated in the pathogenesis of diabetic retinopathy (DR). Polymorphisms in the TGFB1 gene have been associated with DR; however, results are still contradictory. Therefore, the aim of this study was to investigate the potential association between two TGFB1 polymorphisms and DR. This study included 992 patients with diabetes mellitus (DM): 546 patients with DR (cases) and 446 patients without DR and with ≥10 years of DM (controls). The TGFB1 rs1800469 and rs1800470 polymorphisms were genotyped by real-time PCR. Frequency of rs1800469 T/T genotype was higher in controls compared to DR cases (18.3% vs. 12.7%, P= 0.022). This genotype remained associated with protection for DR, adjusting for covariables (OR= 0.604; 95% CI 0.395 - 0.923; P= 0.020, recessive model). The rs1800470 C/C genotype was observed in 25.4% of the controls and 18.0% of the cases (P= 0.015); thus, being associated with protection against DR under the recessive model (OR= 0.589; 95% CI 0.405 - 0.857; P= 0.006), adjusting for covariables. In conclusion, the TGFB1 rs1800469 and rs1800470 polymorphisms are associated with protection against DR in DM patients from Southern Brazil.

Intraretinal Microvascular Abnormalities and Venous Beading Have Different Genetic Profiles in Caucasian Patients with Non-Proliferative Diabetic Retinopathy

Diabetic Retinopathy (DR) is a leading cause of preventable visual impairment in the working age population. Despite the increasing prevalence of DR, there remain gaps in our understanding of its pathophysiology. This is a prospective case-control study comparing the genetic profiles of patients with no DR vs. non-proliferative DR (NPDR) focusing on intraretinal microvascular abnormalities (IRMA) and venous beading (VB) in Caucasians. A total of 596 participants were recruited to the study; 199 with moderate/severe NPDR and 397 with diabetes for at least 5 years without DR. Sixty-four patients were excluded due to technical issues. In total, 532 were analysed; 181 and 351 were in the NPDR group and no DR group, respectively. Those with severe IRMA and VB had distinctly different genetic profiles from each other and from the no DR group, which further supports the theory that these two features of DR might have different etiologies. This also suggests that IRMA and VB are independent risk factors for the development of PDR and may have different pathophysiologies. If these findings are confirmed in larger studies, this could pave the way for personalised treatment options for those more at risk of developing different features of NPDR.

Association between polymorphisms of cytokine genes and diabetic nephropathy: A comprehensive systematic review and meta-analysis

AIM

Diabetic nephropathy (DN) is one of the microvascular complications of diabetes, leading to renal failure. In this study, we sought to systematically investigate the cytokine gene polymorphisms association with DN.

METHODS

A structured bibliographic search on PubMed, Scopus, and EMBASE databases has been performed to identify related papers. The odds ratio and corresponding 95% confidence intervals (CIs) were calculated to estimate the association.

RESULTS

Overall, the pooled results showed that the dominant models of TNF-α rs1800629, IL-1β rs16944, IL-8 rs4073, and IL-10 rs1800896 were associated with increased susceptibility to DN. Also, the pooled analyses of the mutant allele vs wild allele of TNF-α rs1800629, rs1799964, IL-1β rs16944, and IL-8 rs4073 were associated with increased susceptibility to DN. Rs1800629, rs16944, rs4073, and rs1800896 polymorphisms were significantly associated with DN susceptibility, suggesting its potential use as a genetic risk marker in the population.

Association between diabetic retinopathy and polymorphisms of cytokine genes: a systematic review and meta-analysis

INTRODUCTION

Diabetic retinopathy (DR) is a medical condition caused by damage to the blood vessels of retina tissue due to diabetes mellitus. DR leads to injury in neural and vascular structures and is reported to be significantly influenced by inflammation and inflammatory mediators like cytokines. In this study, a systematic review and meta-analysis were performed to analyze the association between cytokine gene polymorphisms and DR.

METHODS

We identified relevant studies from Scopus, PubMed, and Google scholar databases. Allele and genotype frequencies were pooled. Heterogeneity and publication bias were explored. The odds ratio (OR) and corresponding 95% confidence intervals (CIs) were calculated to estimate the relation.

RESULTS

A total of 3337 cases and 4945 controls in 19 eligible studies were included in the meta-analysis. Overall, results indicated the negative association between the cytokine gene polymorphisms and DR susceptibility in the allelic model (IFN-γ (rs2430561): OR 0.64, [CI]: 0.5 to 0.82; and TGF-β (rs1800471): [OR] = 0.15, [CI]: 0.03 to 0.79); and also, in the dominant model (IFN-γ (rs2430561): OR = 0.4, [CI]: 0.22 to 0.75; and TGF-β (rs1800471): OR = 0.14, [CI]: 0.05 to 0.4).

CONCLUSION

The present study suggests that IFN-γ (rs2430561) and TGF-β (rs1800471) polymorphisms are associated with decreased susceptibility to DR.

Relationship between transforming growth factor-β1 and type 2 diabetic nephropathy risk in Chinese population

BACKGROUND

Diabetes mellitus (DM) is divided into four different etiological categories: type 1 DM (T1DM), type 2 DM (T2DM), other specific types, and gestational DM. One severe complication of T2DM is type 2 diabetic nephropathy (T2DN). The possible association of serum transforming growth factor-β1 (TGF-β1) levels and the TGF-β1 T869C gene polymorphism with patient susceptibility to T2DN in Chinese population is unclear at present. This study was conducted to assess these relationships in Chinese population by a meta-analysis.

METHODS

Association reports were searched and pulled from the Cochrane Library, the China Biological Medicine Database (CBM), and PubMed on March 1, 2018, and eligible studies were selected and used for calculations. The results were expressed as weighted mean differences (MD) for continuous data. Odds ratios (OR) were used to express the results for dichotomous data. Additionally, 95% confidence intervals (CI) were calculated.

RESULTS

Forty-eight reports for the relationship between serum TGF-β1 levels and the risk of T2DN and 13 studies on the association of the TGF-β1 T869C gene polymorphism with susceptibility to T2DN in Chinese population were retrieved from this study. Serum TGF-β1 levels in the T2DM group were higher than those in the normal control group (MD = 17.30, 95% CI: 12.69-21.92, P < 0.00001). The serum TGF-β1 level in the T2DN group was significantly higher than that in the normal control group (MD = 70.03, 95% CI: 60.81-79.26, P < 0.00001;). The serum TGF-β1 level in the T2DN group was significantly higher than that in the T2DM group (MD = 56.18, 95% CI: 46.96-65.39, P < 0.00001). Serum TGF-β1 levels in T2DM patients with microalbuminuria were increased when compared with those in T2DM patients with normoalbuminuria. Furthermore, serum TGF-β1 levels in T2DM patients with macroalbuminuria were increased when compared with those in T2DM patients with microalbuminuria. The TGF-β1 T allele, TT allele and CC genotype were associated with T2DN susceptibility in Chinese population (T: OR = 0.74, 95% CI: 0.59-0.92, P = 0.007; TT: OR = 0.55, 95% CI: 0.31-0.96, P = 0.04; CC: OR = 1.38, 95% CI: 1.14-1.67, P = 0.001).

CONCLUSIONS

High levels of TGF-β1 are associated with susceptibility to T2DM, T2DN and the progression of proteinuria in T2DN patients in Chinese population. Further, the TGF-β1 T allele, and TT genotype were protective factors against the onset of T2DN and CC genotype was a risk factor for the susceptibility of T2DN in Chinese populations.

Diabetic macular oedema: under-represented in the genetic analysis of diabetic retinopathy

Diabetic retinopathy, a complication of both type 1 and type 2 diabetes, is a complex disease and is one of the leading causes of blindness in adults worldwide. It can be divided into distinct subclasses, one of which is diabetic macular oedema. Diabetic macular oedema can occur at any time in diabetic retinopathy and is the most common cause of vision loss in patients with type 2 diabetes. The purpose of this review is to summarize the large number of genetic association studies that have been performed in cohorts of patients with type 2 diabetes and published in English-language journals up to February 2017. Many of these studies have produced positive associations with gene polymorphisms and diabetic retinopathy. However, this review highlights that within this large body of work, studies specifically addressing a genetic association with diabetic macular oedema, although present, are vastly under-represented. We also highlight that many of the studies have small patient numbers and that meta-analyses often inappropriately combine patient data sets. We conclude that there will continue to be conflicting results and no meaningful findings will be achieved if the historical approach of combining all diabetic retinopathy disease states within patient cohorts continues in future studies. This review also identifies several genes that would be interesting to analyse in large, well-defined cohorts of patients with diabetic macular oedema in future candidate gene association studies.

The Increased Transforming Growth Factor-β Signaling Induced by Diabetes Protects Retinal Vessels

The roles of transforming growth factor (TGF)-β in extracellular matrix production and vascular remodeling, coupled with increased TGF-β expression and signaling in diabetes, suggest TGF-β as an important contributor to the microangiopathy of diabetic retinopathy and nephropathy. To investigate whether increased TGF-β signaling could be a therapeutic target for preventing retinopathy, we used a pharmacologic approach (SM16, a selective inhibitor of the type 1 TGF-β receptor activin receptor-like kinase 5, orally active) to inhibit the increased, but not the basal, Tgf-β signaling in retinal vessels of diabetic rats. At the level of vascular gene expression, 3.5 months' diabetes induced minimal changes. Diabetes + SM16 for 3 weeks caused widespread changes in gene expression poised to enhance vascular inflammation, thrombosis, leakage, and wall instability; these changes were not observed in control rats given SM16. The synergy of diabetes and SM16 in altering gene expression was not observed in the lung. At the level of vascular network morphology, 7 months' diabetes induced no detectable changes. Diabetes + SM16 for 3 weeks caused instead distorted morphology and decreased density. Thus, in diabetes, retinal vessels become dependent on a small increase in TGF-β signaling via activin receptor-like kinase 5 to maintain early integrity. The increased TGF-β signaling may protect against rapid retinopathy progression and should not be a target of inhibitory interventions.

Overexpression of TSC-22 (transforming growth factor- β-stimulated clone-22) causes marked obesity, splenic abnormality and B cell lymphoma in transgenic mice

In this study, we generated transgenic (Tg) mice, which overexpressed transforming growth factor (TGF)-β stimulated clone-22 (TSC-22), and investigate the functional role of TSC-22 on their development and pathogenesis. We obtained 13 Tg-founders (two mice from C57BL6/J and 11 mice from BDF1). Three of 13 Tg-founders were sterile, and the remaining Tg-founders also could generate only a limited number of the F1 generation. We obtained 32 Tg-F1 mice. Most of the Tg-mice showed marked obesity. Histopathological examination could be performed on 31 Tg-mice; seventeen mice died by some disease in their entire life and 14 mice were killed for examination. Most of the Tg-mice examined showed splenic abnormality, in which marked increase of the megakaryocytes, unclearness of the margin of the red pulp and the white pulp, and the enlargement of the white pulp was observed. B cell lymphoma was developed in 10 (71%) of 14 disease-died F1 mice. These results indicate that constitutive over-expression of TSC-22 might disturb the normal embryogenesis and the normal lipid metabolism, and induce the oncogenic differentiation of hematopoietic cells.

Study of the association of the T869C polymorphism of the transforming growth factor-β1 gene with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common multifactorial disorder characterized by hyperandrogenism, insulin resistance and chronic oligoanovulation. In addition, a number of females with PCOS have ovaries with multiple cysts, an irregular or no menstrual cycle and an imbalance of female hormones compared with normal controls. The transforming growth factor β1 (TGF‑β1) gene is one of the genes associated with obesity and type 2 diabetes, which are characteristic symptoms of PCOS. The present study, therefore, investigated the association between the T869C polymorphism of the TGF‑β1 gene, a single nucleotide polymorphism (SNP) of TGF‑β1 and PCOS. The genomic DNA from 285 patients with PCOS and 129 healthy control individuals was used in the present study. P<0.05 was considered to indicate a statistically significant difference between the groups. The present study findings suggested that the frequency of genotypes provided no significant association between the T869C polymorphism in the TGF‑β1 gene and patients with PCOS. Although the present study concluded that the T869C polymorphism in the TGF‑β1 gene is not associated with the pathogenesis of PCOS, further studies regarding the correlation between other SNPs of the TGF‑β1 gene and PCOS are required.

Association of transforming growth factor-β1 T869C gene polymorphism with diabetic nephropathy risk

AIM

A possible association between the transforming growth factor-β1 (TGF-β1) T869C gene polymorphism and the risk of developing diabetic nephropathy (DN) remains unclear. This investigation was performed to assess if an association between the TGF-β1 T869C gene polymorphism and DN risk exists by using meta-analysis to combine comparable studies, thereby increasing sample size and statistical significance, and to identify patterns in various studies.

METHODS

The association reports were identified from PubMed, Cochrane Library, and CBM-disc (China Biological Medicine Database) on 1 May 2013, and eligible studies were recruited and synthesized.

RESULTS

Fifty reports were recruited into this meta-analysis for the association of the TGF-β1 T869C gene polymorphism with DN risk. The TT genotype in the overall population was shown to be associated with DN risk (odds ratio (OR) = 0.74, 95% confidence interval (CI): 0.56-0.98, P = 0.04). In the sub-group analysis, CC genotype was associated with DN risk in Asians, Caucasians, and Africans. However, the sample size for Caucasians and Africans was relatively small. Furthermore, T allele was distinctly associated with the risk of developing DN in the Asian population (OR = 0.76, 95% CI: 0.62-0.92, P = 0.005).

CONCLUSIONS

The TT genotype of TGF-β1 T869C in the overall population was associated with DN risk, whereas the CC genotype and T allele were distinctly associated with DN risk in the Asian population. Nonetheless, additional studies are required to firmly establish a correlation between the aforementioned polymorphism and DN risk.

Developments in renal pharmacogenomics and applications in chronic kidney disease

Chronic kidney disease (CKD) has shown an increasing prevalence in the last century. CKD encompasses a poor prognosis related to a remarkable number of comorbidities, and many patients suffer from this disease progression. Once the factors linked with CKD evolution are distinguished, it will be possible to provide and enhance a more intensive treatment to high-risk patients. In this review, we focus on the emerging markers that might be predictive or related to CKD progression physiopathology as well as those related to a different pattern of response to treatment, such as inhibitors of the renin–angiotensin system (including angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers; the vitamin D receptor agonist; salt sensitivity hypertension; and progressive kidney-disease markers with identified genetic polymorphisms). Candidate-gene association studies and genome-wide association studies have analyzed the genetic basis for common renal diseases, including CKD and related factors such as diabetes and hypertension. This review will, in brief, consider genotype-based pharmacotherapy, risk prediction, drug target recognition, and personalized treatments, and will mainly focus on findings in CKD patients. An improved understanding will smooth the progress of switching from classical clinical medicine to gene-based medicine.

Diabetic macular edema: new concepts in patho-physiology and treatment

Diabetic macular edema (DME), a serious eye complication caused primarily by hyperglycemia, is one of the major causes of blindness. DME, which is characterized by cystic retinal thickening or lipid deposition, is prone to relapse after successful treatment. DME is a complex pathological process caused by multiple factors, including breakdown of the inner and outer blood-retinal barriers, oxidative stress, and elevated levels of vascular endothelial growth factor which have been demonstrated in both preclinical and clinical studies. Starling's law theory explains many of the features of DME. Early detection and treatment of DME can prevent vision loss. Current effective interventions for DME include treatment of systemic risk factors, such as elevated blood glucose, blood pressure and dyslipidemia. Ophthalmic treatments include laser photocoagulation, surgery and intraocular pharmacotherapy. New drugs, which are given by intraocular injection, have emerged in recent years to become first line treatment for DME that affects the central macula with loss of vision. Laser photocoagulation is still the gold standard of treatment for DME which does not involve the central macular. This review outlines these new treatments with particular emphasis on the optimal timing of how they are given.

TGF-beta1 gene polymorphism in association with diabetic retinopathy susceptibility: a systematic review and meta-analysis

Background

Transforming growth factor-beta (TGF-β1) gene has been regarded as an important mechanism in angiogenesis, endothelial cell proliferation, adhesion,and the deposition of extracellular matrix. The TGF-β1 gene may be involved in the development of diabetic retinopathy (DR) through disrupting angiogenesis. However, studies investigating the relationship between −509C/T and +869T/C(L10P) polymorphisms and DR yielded contradictory and inconclusive outcomes. In order to realize these ambiguous findings, a meta-analysis was performed to assess the association between the TGF-β1 gene polymorphisms and susceptibility to DR.

Methodology/Principal Findings

We conducted a search of all English reports on studies for the association between the TGF-β1 gene polymorphisms and susceptibility to DR using Medline, the Cochrane Library, EMbase, Web of Science, Google (scholar), and all Chinese reports were identified manually and on-line using CBMDisc, Chongqing VIP database, and CNKI database. The strict selection criteria and exclusion criteria were determined, and odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of associations. The fixed or random effect model was selected based on the heterogeneity test among studies. Publication bias was estimated using Begg's funnel plots and Egger's regression test.

Results

A total of three studies were included in the meta-analysis and all included studies analyzed patients with type 2 diabetes. For +869T/C(L10P) polymorphism, significant association was observed in an allele model (L versus P: OR = 1.34, 95%CI = 1.03–1.73) and the recessive model (LL versus LP+PP: OR = 1.70, 95%CI = 1.13–2.56). As regards −509C/T polymorphism, no obvious associations were found for all genetic models.

Conclusions

This meta-analysis suggested that the +869T/C(L10P) polymorphism in TGFβ1 gene would be a potential protect factor for DR. However, the −509C/T polymorphism is not associated with DR.

The Role of Transforming Growth Factor-Beta in Diabetic Nephropathy

Several studies have demonstrated that chronic and low-grade inflammation is closely linked to type 2 diabetes mellitus. The associated mechanisms are related to synthesis and release of proinflammatory and anti-inflammatory cytokines, mainly by the adipose tissue. Moreover, there are evidences that cytokines and adhesion molecules are important for development of diabetic nephropathy. Among the cytokines associated with inflammatory responses in type 2 diabetes mellitus, the transforming growth factor-β (TGF-β) has been recognized as a central player in the diabetic nephropathy being involved in the development of glomerulosclerosis and interstitial fibrosis, as observed in the course of end-stage renal disease. Although TGF-β1 is classically an anti-inflammatory immune mediator it has been shown that in the presence of IL-6, which increases before the onset of T2D, TGF-β1 favors the differentiation of T helper 17 (Th17) cells that are activated in many pro-inflammatory conditions. Since TGF-β1 mRNA and consequently serum TGF-β1 levels are under genetic control, this review aims to discuss the relationship of TGF-β1 levels and polymorphisms in the development of nephropathy in type 2 diabetes mellitus.

A meta-analysis of the association of G915C, G800A, C509T gene polymorphism of transforming growth factor-β1 with diabetic nephropathy risk

This meta-analysis was conducted to evaluate the association of transforming growth factor-β1 (TGF-β1) G915C, G800A, C509T gene polymorphism with the risk of diabetic nephropathy (DN). The association literatures were identified from PubMed, Cochrane Library, and CBM-disc (China Biological Medicine Database) on March 1, 2013, and eligible reports were recruited and synthesized. Seven reports were recruited into this meta-analysis for the association of TGF-β1 G800A, C509T, G915C gene polymorphism with DN risk. GG genotype, CC genotype, and C allele of TGF-β1 G915C were not associated with the DN risk (GG: OR = 0.84, 95% CI: 0.62-1.14, p = 0.27; CC: OR = 1.05, 95% CI: 0.50-2.22, p = 0.90; C allele: OR = 1.16, 95% CI: 0.88-1.51, p = 0.29). Furthermore, TGF-β1 G800A, C509T gene polymorphism was not associated with the DN risk. In conclusion, TGF-β1 G915C, G800A, and C509T gene polymorphism are not associated with the DN risk. However, more studies should be performed to confirm this relationship in the future.

Association of rs1800471 polymorphism of TGFB1 gene with chronic kidney disease occurrence and progression and hypertension appearance

INTRODUCTION

Transforming growth factor β1 (TGF-β1) is a cytokine involved in the process of pathological tissue sclerosis, which is part of the pathophysiological mechanism of end stage renal disease development. The aim of the study was to evaluate the association of the single nucleotide polymorphism rs1800471 of the TGFB1 gene with chronic kidney disease (CKD) occurrence and progression as well as hypertension appearance.

MATERIAL AND METHODS

It was a case-control study where 109 patients with CKD and 111 very old people were enrolled. The association of the studied polymorphism with mentioned diseases was assessed in the whole study group as well as in the subgroups stratified according to the underlying etiology of CKD: nephropathy in type 1 diabetes (n = 13), chronic glomerulonephritis (n = 50) and chronic interstitial nephritis (n = 46).

RESULTS

No association of CKD progression with rs1800471 polymorphism was observed. The C allele was identified as the one associated with higher risk of the disease occurrence in the dominant model of inheritance (p = 0.035). The C allele in women, opposite to male gender, was associated with higher risk of CKD development (p = 0.038). GG genotype was associated with elevated risk of hypertension appearance (p = 0,0021).

CONCLUSIONS

Due to the lack of accordance with previously performed studies it is still impossible to state an unequivocal conclusion regarding the association between rs1800471 polymorphism of the TGFB1 gene and risk of CKD occurrence and progression as well as hypertension appearance. That is why it is necessary to perform further studies in this field.

Fenofibrate Inhibits Endothelin-1 Expression by Peroxisome Proliferator–Activated Receptor α–Dependent and Independent Mechanisms in Human Endothelial Cells

Objective—

Dyslipidemia contributes to endothelial dysfunction in type 2 diabetes mellitus. Fenofibrate (FF), a ligand of the peroxisome proliferator–activated receptor-α (PPARα), has beneficial effects on microvascular complications. FF may act on the endothelium by regulating vasoactive factors, including endothelin-1 (ET-1). In vitro, FF decreases ET-1 expression in human microvascular endothelial cells. We investigated the molecular mechanisms involved in the effect of FF treatment on plasma levels of ET-1 in type 2 diabetes mellitus patients.

Methods and Results—

FF impaired the capacity of transforming growth factor-β to induce ET-1 gene expression. PPARα activation by FF increased expression of the transcriptional repressor Krüppel-like factor 11 and its binding to the ET-1 gene promoter. Knockdown of Krüppel-like factor 11 expression potentiated basal and transforming growth factor-β–stimulated ET-1 expression, suggesting that Krüppel-like factor 11 downregulates ET-1 expression. FF, in a PPARα-independent manner, and insulin enhanced glycogen synthase kinase-3β phosphorylation thus reducing glycogen synthase kinase-3 activity that contributes to the FF-mediated reduction of ET-1 gene expression. In type 2 diabetes mellitus, improvement of flow-mediated dilatation of the brachial artery by FF was associated with a decrease in plasma ET-1.

Conclusion—

FF decreases ET-1 expression by a PPARα-dependent mechanism, via transcriptional induction of the Krüppel-like factor 11 repressor and by PPARα-independent actions via inhibition of glycogen synthase kinase-3 activity.

The linkage between inflammation and Type 2 diabetes mellitus

The Type 2 diabetes mellitus (DM2) is considered nowadays as one of the most important chronic disturbances because of the significant number of people with diabetes and its severe complications, responsible for elevated indexes of morbidity and mortality. DM2 is characterized by several degrees of insulin resistance and relative deficiency in its secretion. Genetic and environmental factors have been described as of major importance in the DM2 development as obesity, which is directly correlated with development of resistance in peripheral tissues and inflammatory state in metabolic activated adipose tissue. Inflammatory responses may have a dual role in DM2, since it may have either a causal relationship leading to resistance to insulin or may be intensified by the hyperglycemic state, resulting in DM2 complications. In this review, we discuss the association of polymorphisms in genes encoding inflammatory cytokines and the increased level of these pro-inflammatory markers, associated to chronic pathologic conditions in DM2.

Association between the T869C polymorphism of transforming growth factor-beta 1 and diabetic nephropathy: a meta-analysis

Accumulating evidence has suggested that transforming growth factor-beta 1 (TGF-β1) is a functional candidate for diabetic nephropathy (DN). However, association studies investigating the relationship of TGF-β1 gene T869C polymorphism and DN generate inconsistent results. To comprehensively clarify this issue, we performed a meta-analysis to evaluate the impact of the polymorphism on DN. We searched studies from PubMed and China National Knowledge Infrastructure (CNKI) through March 2011. Pooled ORs were calculated under allelic/additive/dominant/recessive/over-dominant genetic models. Nine studies with 1776 cases and 1740 controls were included. Our results indicated that C allele of T869C conferred a significantly increased risk of DN compared with T allele (OR = 1.25, 95% CI: 1.05-1.48) for allelic contrast. Similar results were also found under additive (OR = 1.57, 95% CI: 1.10-2.23) and dominant (OR = 1.40, 95% CI: 1.06-1.85) genetic models. However, subgroup analyses stratified by types of diabetes showed that significantly increased risks were only observed in type 2 diabetic patients, and the association persistently existed in further analysis for Asian populations. As for type 1 diabetic subjects, no significant association was detected under all the genetic models (P > 0.05). Our meta-analysis suggested that the TGF-β1 T869C polymorphism conferred an elevated risk of DN. However, significant associations were only observed in type 2 diabetic patients.

Genome-wide association study of diabetic retinopathy in a Taiwanese population

PURPOSE

Diabetic retinopathy (DR) is a microvascular complication of diabetes with a complex multifactorial pathogenesis. The aim of this study was to identify the susceptibility genes that increase the risk of DR in type 2 diabetes (T2D) and to further elucidate the underlying mechanism of DR pathogenesis.

DESIGN

A case-control study.

PARTICIPANTS

We included 749 unrelated individuals with T2D (174 with DR and 575 without DR) and 100 nondiabetic controls.

METHODS

We conducted a genome-wide association study using Illumina HumanHap550-Duo BeadChips.

MAIN OUTCOME MEASURES

Compared with the genotypic distribution of single nucleotide polymorphisms (SNPs) between subjects with DR and without DR.

RESULTS

Using statistical models, we selected a total of 12 SNPs with P-values <1 × 10(-6) that were associated with DR. After controlling for diabetes duration and hemoglobin A(1C), 9 of the 12 SNPs located on 5 chromosomal regions were found to be associated with DR. Five loci not previously associated with DR susceptibility were identified in and around the following genes: MYSM1 (Myb-like, SWIRM, and MPN domains 1) located on chromosome 1p (odds ratio [OR], 1.50; 95% confidence interval [CI], 1.03-2.20); PLXDC2 (plexin domain-containing 2) located on the chromosome 10p (OR, 1.67; 95% CI, 1.06-2.65); ARHGAP22 (Rho GTPase-activating protein 22) located on chromosome 10q (OR, 1.65; 95% CI, 1.05-2.60); and HS6ST3 (heparan sulfate 6-O-sulfotransferase 3) located on chromosome 13q (OR, 2.33; 95% CI, 1.13-4.77). The SNPs rs13163610 and rs17376456 located in the unknown gene on chromosome 5q were also associated with DR (OR, 3.63; 95% CI, 1.38-9.58).

CONCLUSIONS

We identified a genetic association for susceptibility to DR in 5 novel chromosomal regions and PLXDC2 and ARHGAP22, the latter 2 of which are genes implicated in endothelial cell angiogenesis and increased capillary permeability. These findings suggest unsuspected pathways in the pathogenesis of DR.

Single nucleotide polymorphism at rs1982073:T869C of the TGFbeta 1 gene is associated with the risk of radiation pneumonitis in patients with non-small-cell lung cancer treated with definitive radiotherapy

PURPOSE

In search of reliable biologic markers to predict the risk of normal tissue damage by radio(chemo)therapy before treatment, we investigated the association between single nucleotide polymorphisms (SNPs) in the transforming growth factor 1 (TGFbeta1) gene and risk of radiation pneumonitis (RP) in patients with non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Using 164 available genomic DNA samples from patients with NSCLC treated with definitive radio(chemo)therapy, we genotyped three SNPs of the TGFbeta1 gene (rs1800469:C-509T, rs1800471:G915C, and rs1982073:T869C) by polymerase chain reaction restriction fragment length polymorphism method. We used Kaplan-Meier cumulative probability to assess the risk of grade > or = 3 RP and Cox proportional hazards analyses to evaluate the effect of TGFbeta1 genotypes on such risk.

RESULTS

There were 90 men and 74 women in the study, with median age of 63 years. Radiation doses ranging from 60 to 70 Gy (median = 63 Gy) in 30 to 58 fractions were given to 158 patients (96.3%) and platinum-based chemotherapy to 147 (89.6%). Grade > or = 2 and grade > or = 3 RP were observed in 74 (45.1%) and 36 patients (22.0%), respectively. Multivariate analysis found CT/CC genotypes of TGFbeta1 rs1982073:T869C to be associated with a statistically significantly lower risk of RP grades > or = 2 (hazard ratio [HR] = 0.489; 95% CI, 0.227 to 0.861; P = .013) and grades > or = 3 (HR = 0.390; 95% CI, 0.197 to .774; P = 0.007), respectively, compared with the TT genotype, after adjustment for Karnofsky performance status, smoking status, pulmonary function, and dosimetric parameters.

CONCLUSION

Our results showed that CT/CC genotypes of TGFbeta1 rs1982073:T869C gene were associated with lower risk of RP in patients with NSCLC treated with definitive radio(chemo)therapy and thus may serve as a reliable predictor of RP.