Elevated micronuclei frequency in type 2 diabetes with high glycosylated hemoglobin

Occupational exposure to radiation among health workers: Genome integrity and predictors of exposure

The current study aimed to investigate genomic instabilities in healthcare workers who may experience varying levels of radiation exposure through various radiological procedures. It also sought to determine if factors related to the work environment and dosimeter reading could effectively explain the observed genomic instabilities. Utilizing the cytokinesis-block micronucleus assay (CBMN) on peripheral blood lymphocytes, we assessed a spectrum of genomic aberrations, including nucleoplasmic bridge (NPB), nuclear budding (NBUD), micronucleus (MN) formation, and total DNA damage (TDD). The study uncovered a statistically significant increase in the occurrence of distinct DNA anomalies among radiology workers (with a significance level of P < 0.0001 for all measurements). Notably, parameters such as total working hours, average work duration, and time spent in projection radiography exhibited significant correlations with MN and TDD levels in these workers. The dosimeter readings demonstrated a positive correlation with the frequency of NPB and NBUD, indicating a substantial association between radiation exposure and these two genomic anomalies. Our multivariable models identified the time spent in projection radiography as a promising parameter for explaining the overall genomic instability observed in these professionals. Thus, while dosimeters alone may not fully explain elevated total DNA damage, intrinsic work environment factors hold potential in indicating exposure levels for these individuals, providing a complementary approach to monitoring.

OUP accepted manuscript

Type 2 diabetes (T2D) is associated with elevated frequencies of micronuclei (MNi) and other DNA damage biomarkers. Interestingly, individuals with T2D are more likely to be deficient in micronutrients (folic acid, pyridoxal-phosphate, cobalamin) that play key roles in one-carbon metabolism and maintaining genomic integrity. Furthermore, it has recently been shown that deficiencies in these nutrients, in particular folic acid leaves cells susceptible to glucose-induced DNA damage. Therefore, we sought to investigate if the B lymphoblastoid WIL2-NS cell line cultured under folic acid-deficient conditions was more sensitive to DNA damage induced by glucose, or the reactive glycolytic byproduct methylglyoxal (MGO) and subsequent advanced glycation endproduct formation. Here, we show that only WIL2-NS cultured under folic acid-deficient conditions (23 nmol/l) experience an increase in MNi frequency when exposed to high concentrations of glucose (45 mmol/l) or MGO (100 µmol/l). Furthermore, we showed aminoguanidine, a well-validated MGO and free radical scavenger was able to prevent further MNi formation in folic acid-deficient cells exposed to high glucose, which may be due to a reduction in MGO-induced oxidative stress. Interestingly, we also observed an increase in MGO and other dicarbonyl stress biomarkers in folic acid-deficient cells, irrespective of glucose concentrations. Overall, our evidence shows that folic acid-deficient WIL2-NS cells are more susceptible to glucose and/or MGO-induced MNi formation. These results suggest that individuals with T2D experiencing hyperglycemia and folic acid deficiency may be at higher risk of chromosomal instability.

Effects of a 3-Week Hospital-Controlled Very-Low-Calorie Diet in Severely Obese Patients

Although a very-low-calorie diet (VLCD) is considered safe and has demonstrated benefits among other types of diets, data are scarce concerning its effects on improving health and weight loss in severely obese patients. As part of the personalized weight loss program developed at the Duga Resa Special Hospital for Extended Treatment, Croatia, we evaluated anthropometric, biochemical, and permanent DNA damage parameters (assessed with the cytochalasin B-blocked micronucleus cytome assay-CBMN) in severely obese patients (BMI ≥ 35 kg m-2) after 3-weeks on a 567 kcal, hospital-controlled VLCD. This is the first study on the permanent genomic (in)stability in such VLCD patients. VLCDs caused significant decreases in weight (loss), parameters of the lipid profile, urea, insulin resistance, and reduced glutathione (GSH). Genomic instability parameters were lowered by half, reaching reference values usually found in the healthy population. A correlation was found between GSH decrease and reduced DNA damage. VLCDs revealed susceptible individuals with remaining higher DNA damage for further monitoring. In a highly heterogeneous group (class II and III in obesity, differences in weight, BMI, and other categories) consisting of 26 obese patients, the approach demonstrated its usefulness and benefits in health improvement, enabling an individual approach to further monitoring, diagnosis, treatment, and risk assessment based on changing anthropometric/biochemical VLCD parameters, and CBMN results.

Association between glycation biomarkers, hyperglycemia, and micronucleus frequency: A meta -analysis

Micronucleus assay has been used as a biomarker of DNA damage, chromosomal instability, cancer risk and accelerated aging. In this review, a meta-analysis was performed to assess the association between micronuclei (MNi) and diseases with increased advanced glycation end products (AGEs) and HbA1c. The review identified eight studies with 632 subjects with disease and 547 controls. The Mean Ratio (MRi) for AGE levels (MRi = 2.92, 95 %CI: 2.06-4.13, P < 0.00001) and HbA1c levels (MRi = 1.32, 95 %CI: 1.12-1.56, P = 0.001) were significantly higher in the disease group compared to healthy controls. The meta-analysis indicated that the overall estimates of MRi for MNi was 1.83 (95 %CI: 1.38-2.42, p < 0.0001) in subjects with disease compared to controls. Significant increases in MRi for MNi were also observed in the following sub-groups: subjects with disease for elevated AGEs (MRi = 1.62, 95 %CI: 1.12-2.35, P = 0.01), elevated HbA1c (MRi = 2.13, 95 %CI: 1.33-3.39, P = 0.002), lymphocytes MNi (MRi = 1.74, 95 %CI: 1.29-2.33, P = 0.0003), exfoliated buccal cells MNi (MRi = 2.86, 95 %CI: 1.19-6.87, P = 0.02), type 2 diabetes mellitus (T2DM) (MRi = 1.99, 95 %CI: 1.17-3.39, P = 0.01), chronic renal disease (MRi = 1.68, 95 %CI: 1.18-2.38, P = 0.004) and other disease groups (MRi = 2.52, 95 %CI: 1.28-4.96, P = 0.008). The results of this review suggest that MNi could be used as a biomarker of DNA damage and chromosomal instability in degenerative disease where increased AGEs and HbA1c are implicated. The lack of heterogeneity for MN frequency when considered either for all studies or subgroup strengthened the MRi of the meta-analysis. However, the lack of significant association between MRi for MNi and MRi for AGEs or HbA1c indicates that the case-control studies investigated may be confounded by other variables. Thus, larger studies with long term AGE exposure is warranted to further understand the role of MN formation in the initiation and progression of diseases caused by excessive glycation.

Dietary sugars and related endogenous advanced glycation end-products increase chromosomal DNA damage in WIL2-NS cells, measured using cytokinesis-block micronucleus cytome assay

This study investigated the effect of glucose and fructose, and advanced glycation end-products (AGEs) on genome damage in WIL2-NS cells, measured using the cytokinesis-block micronucleus cytome (CBMN-Cyt) assay. The effect of AGEs was investigated using the bovine serum albumin (AGE-BSA) model system induced either with glucose (Glu-BSA) or with fructose (Fru-BSA). Liquid chromatography-mass spectrometry (LC-MS/MS) analysis showed higher Nε-carboxymethyllysine (CML; 26.76 ± 1.09 nmol/mg BSA) levels in the Glu-BSA model. Nε-Carboxyethyllysine (CEL; 7.87 ± 0.19 nmol/mg BSA) and methylglyoxal-derived hydroimidazolone-1 (MG-H1; 69.77 ± 3.74 nmol/mg BSA) levels were higher in the Fru-BSA model. Genotoxic effects were measured using CBMN-Cyt assay biomarkers [binucleated(BN) cells with micronuclei (MNi), BN with nucleoplasmic bridges (NPBs) and BN with nuclear buds (NBuds)] following 9 days of treatment with either glucose, fructose, Glu-BSA or Fru-BSA. Fructose treatment exerted a significant genotoxic dose-response effect including increases of BN with MNi (R2 = 0.7704; P = 0.0031), BN with NPBs (R2 = 0.9311; P < 0.0001) and BN with NBuds (R2 = 0.7118; P = 0.0091) on cells, whereas the DNA damaging effects of glucose were less evident. High concentrations of AGEs (400-600 µg/ml) induced DNA damage; however, there was no effect on cytotoxicity indices (necrosis and apoptosis). In conclusion, this study demonstrates a potential link between physiologically high concentrations of reducing sugars or AGEs with increased chromosomal damage which is an important emerging aspect of the pathology that may be induced by diabetes. Ultimately, loss of genome integrity could accelerate the rate of ageing and increase the risk of age-related diseases over the long term. These findings indicate the need for further research on the effects of glycation on chromosomal instability and to establish whether this effect is replicated in humans in vivo.

Micronuclei, inflammation and auto-immune disease

Auto-immune diseases (AUD) are characterized by an immune response to antigenic components of the host itself. The etiology of AUD is not well understood. The available evidence points to an interaction between genetic, epigenetic, environmental, infectious and life-style factors. AUD are more prevalent in women than in men; sex hormones play a crucial role in this sex bias. Micronuclei (MN) emerged as a new player in the induction of AUD, based on the capacity of DNA-sensors to detect self-DNA that leaks into the cytoplasm from disrupted MN and induce the cGAS-STING pathway triggering an innate auto-immune response and chronic inflammation. It was found that inflammation can induce MN and MN can induce inflammation, leading to a vicious inflammation-oxidative-DNA damage-MN-formation-chromothripsis cycle. MN originating from sex chromosome-loss may induce inflammation and AUD. We performed a systematic review of studies reporting MN in patients with systemic or organ-specific AUD. A meta-analysis was performed on lymphocyte MN in diabetes mellitus (10 studies, 457 patients/290 controls) and Behcet's disease (3 studies, 100 patients/70 controls) and for buccal MN in diabetes mellitus (11 studies, 507 patients/427 controls). A statistically significant increase in patients compared to controls was found in the meta-analyses providing an indication of an association between MN and AUD. A 36%-higher mean-MRi in buccal cells (3.8+/-0.7) was found compared to lymphocytes (2.8+/-0.7)(P = 0.01). The meta-MRi in lymphocytes and buccal cells (1.7 and 3.0 respectively) suggest that buccal cells may be more sensitive. To assess their relative sensitivity, studies with measurements from the same subjects would be desirable. It is important that future studies (i) investigate, in well-designed powered studies, the prospective association of MN-formation with AUD and (ii) explore the molecular mechanisms by which chromosome shattering in MN and the release of chromatin fragments from MN lead to the formation of auto-antibodies.

Micronuclei and disease - Report of HUMN project workshop at Rennes 2019 EEMGS conference

The "Micronuclei and Disease" workshop was organized by the HUMN Project consortium and hosted by the European Environmental Mutagen and Genomics Society at their annual meeting in Rennes, France, on 23 May 2019. The program of the workshop focused on addressing the emerging evidence linking micronucleus (MN) frequency to human disease. The first objective was to review what has been published and evaluate the level and quality of evidence for the connection between MN frequency and various diseases through all life stages. The second objective was to identify the knowledge gaps and what else needs to be done to determine the clinical utility of MN assays as predictors of disease risk and of prognosis when disease is active. Speakers at the workshop discussed the association of MN frequency with inflammation, infertility, pregnancy complications, obesity, diabetes, cardiovascular disease, kidney disease, cervical and bladder cancer, oral head and neck cancer, lung cancer, accelerated ageing syndromes, neurodegenerative diseases, and a road-map on how to utilise this knowledge was proposed. The outcomes of the workshop indicated that there are significant opportunities for translating the application of MN assays into clinical practice to improve disease prevention and risk management and to inform public health policy.

Micronuclei and Their Association with Infertility, Pregnancy Complications, Developmental Defects, Anaemias, Inflammation, Diabetes, Chronic Kidney Disease, Obesity, Cardiovascular Disease, Neurodegenerative Diseases and Cancer

Micronuclei (MN) are a strong cytogenetic indicator of a catastrophic change in the genetic structure and stability of a cell because they originate from either chromosome breaks or whole chromosomes that have been lost from the main nucleus during cell division. The resulting genetic abnormalities can to lead to cellular malfunction, altered gene expression and impaired regenerative capacity. Furthermore, MN are increased as a consequence of genetic defects in DNA repair, deficiency in micronutrients required for DNA replication and repair and exposure to genotoxic chemicals and ultraviolet or ionising radiation. For all of these reasons, the measurement of MN has become one of the best-established methods to measure DNA damage in humans at the cytogenetic level. This chapter is a narrative review of the current evidence for the association of increased MN frequency with developmental and degenerative diseases. In addition, important knowledge gaps are identified, and recommendations for future studies required to consolidate the evidence are provided. The great majority of published studies show a significant association of increased MN in lymphocytes and/or buccal cells with infertility, pregnancy complications, developmental defects, anaemias, inflammation, diabetes, cardiovascular disease, kidney disease, neurodegenerative diseases and cancer. However, the strongest evidence is from prospective studies showing that MN frequency in lymphocytes predicts cancer risk and cardiovascular disease mortality.

Efficacy of oral exfoliative cytology in diabetes mellitus patients: a light microscopic and confocal microscopic study

AIM

Diabetes mellitus (DM) has become a global problem. By monitoring the health status of these individuals, diabetic complications can be prevented. We aimed to analyze alterations in the morphology and cytomorphometry of buccal epithelial cells of type 2 DM patients using oral exfoliative cytology technique and determine its importance in public health screening, diagnosis and monitoring of diabetes mellitus.

MATERIALS AND METHODS

The study was carried out in 100 type 2 DM patients and 30 healthy individuals. Smears were taken from the right buccal mucosa and stained by the Papanicolaou technique. Staining with Acridine orange was carried out to view qualitative changes with confocal laser scanning microscope (LSM-510 Meta). The cytomorphometry was evaluated using IMAGE PRO PLUS 5.5 software with Evolution LC camera. All findings were statistically analyzed.

RESULTS

The results showed that with increase in fasting plasma glucose levels, there is significant increase in nuclear area, decrease in cytoplasmic area, and increase in nuclear cytoplasmic ratio (p < 0.05) when compared to the control group. Various qualitative changes were noted, such as cell degeneration, micronuclei, binucleation, intracytoplasmic inclusion, candida and keratinization.

CONCLUSION

In the present study, we found significant alterations in the cytomorphometry and cytomorphology of buccal epithelial cells of type 2 DM patients. This study supports and extends the view that these cellular changes can alert the clinician to the possibility of diabetes and aid in monitoring of diabetes throughout the lifetime of the patient.

DNA damage in non-communicable diseases: A clinical and epidemiological perspective

Non-communicable diseases (NCDs) are a leading cause of death and disability, representing 63% of the total death number worldwide. A characteristic phenotype of these diseases is the accelerated aging, which is the result of phenomena such as accumulated DNA damage, telomere capping loss and subcellular irreversible/nonrepaired oxidative damage. DNA damage, mostly oxidative, plays a key role in the development of most common NCDs. The present review will gather some of the most relevant knowledge concerning the presence of DNA damage in NCDs focusing on cardiovascular diseases, diabetes, chronic obstructive pulmonary disease, and neurodegenerative disorders, and discussing a selection of papers from the most informative literature. The challenge of comorbidity and the potential offered by new systems approaches for introducing these biomarkers into the clinical decision process will be discussed. Systems Medicine platforms represent the most suitable approach to personalized medicine, enabling to identify new patterns in the pathogenesis, diagnosis and prognosis of chronic diseases.

High levels of γ-H2AX foci and cell membrane oxidation in adolescents with type 1 diabetes

Oxidative stress caused by an excess of free radicals is implicated in the pathogenesis and development of type 1 diabetes mellitus (T1DM) and, in turn, it can lead to genome damage, especially in the form of DNA double-strand break (DSB). The DNA DSB is a potentially carcinogenic lesion for human cells. Thus, we aimed to evaluate whether the level of oxidative stress was increased in peripheral blood lymphocytes of a group of affected adolescents. In 35 T1DM adolescents and 19 healthy controls we assessed: (1) spontaneous and H2O2-induced oxidation of cell membrane using a fluorescence lipid probe; (2) spontaneous and LPS-induced expression of iNOS protein and indirect NO determination via cytofluorimetric analysis of O2(-); (3) immunofluorescent detection of the basal level of histone H2AX phosphorylation (γ-H2AX foci), a well-validated marker of DNA DSB. In T1DM, the frequencies of oxidized cells, both spontaneous and H2O2-induced (47.13±0.02) were significantly higher than in controls (35.90±0.03). Patients showed, in general, both a reduced iNOS expression and production of NO. Furthermore, the level of spontaneous nuclear damage, quantified as γ-H2AX foci, was markedly increased in T1DM adolescents (6.15±1.08% of γ-H2AX(+) cells; 8.72±2.14 γ-H2AXF/n; 9.26±2.37 γ-H2AXF/np), especially in females. In the present study, we confirmed the role that oxidative stress plays in the disease damaging lipids of cell membrane and, most importantly, causing genomic damage in circulating white blood cells of affected adolescents. This also indicates that oxidative stress can affect several tissues in the body. However, although the observed DNA damage is a clear indication that the proper DNA repair mechanisms are activated, the risk for young T1DM subjects of developing not only cardiovascular complications but also some type of cancer cannot be ruled out. In this view, females, probably due to hormonal imbalance typical of adolescence, might represent a more susceptible population.

Elevated frequencies of micronuclei in pregnant women with type 1 diabetes mellitus and in their newborns

Pregestational diabetes mellitus (type 1 and type 2) affects about 1% of the obstetric population. In diabetes, persistent hyperglycemia can be a source of DNA damage via overproduction of reactive oxygen species (ROS). Using the cytokinesis-block micronucleus (CBMN) test, we measured the frequencies of micronuclei (MN) per 1000 binucleated (BN) cells in pregnant women (mothers) with type 1 diabetes mellitus (T1DM) and in their newborns. Peripheral blood lymphocytes were collected from 17 pregnant women with T1DM and cord-blood lymphocytes from their 17 newborns. The control group included 40 pregnant women (mothers) without diabetes mellitus (DM) and their 40 newborns. In the group of pregnant women with T1DM, the mean number of MN per 1000 BN cells was 2.35 (±1.07), significantly (p<0.001) higher than in the control group of pregnant women (0.86±0.90). The frequency value in the group of newborns of T1DM mothers was 1.42 (±0.60), significantly (p<0.05) higher than in the corresponding control group (0.67±0.79). The value in the group of mothers with T1DM was significantly (p<0.05) higher than in their newborns. Comparing mothers without DM with their newborns, no significant frequency differences were observed. No significant correlations were observed between MN frequencies in mothers with T1DM and either the frequencies in their newborns, the duration of diabetes, or HbA1C levels. Our results indicate that T1DM is accompanied by increased frequencies of MN in pregnant women and their newborns.

Vitamin C intake reduces the cytotoxicity associated with hyperglycemia in prediabetes and type 2 diabetes

Hyperglycemia leads to the formation of free radicals and advanced glycation end-products (AGEs). Antioxidants can reduce the level of protein glycation and DNA damage. In this study, we compared the levels of vitamin C intake, which is among the most abundant antioxidants obtained from diet, with the levels of fasting plasma glucose (FPG), glycated hemoglobin (A1C), DNA damage, and cytotoxicity in prediabetic subjects and type 2 diabetic subjects. Our results indicated that there was no significant correlation between FPG or A1C and DNA damage parameters (micronuclei, nucleoplasmic bridges, and nuclear buds). FPG and A1C correlated with necrosis (r = 0.294; P = 0.013 and r = 0.401; P = 0.001, resp.). Vitamin C intake correlated negatively with necrosis and apoptosis (r = −0.246; P = 0.040, and r = −0.276; P = 0.021, resp.). The lack of a correlation between the FPG and A1C and DNA damage could be explained, at least in part, by the elimination of cells with DNA damage by either necrosis or apoptosis (cytotoxicity). Vitamin C appeared to improve cell survival by reducing cytotoxicity. Therefore, the present results indicate the need for clinical studies to evaluate the effect of low-dose vitamin C supplementation in type 2 diabetes.

DNA and oxidative damages decrease after ingestion of folic acid in patients with type 2 diabetes

BACKGROUND AND AIMS

Type 2 diabetes mellitus (T2DM) is a chronic degenerative disease that promotes autoxidation of sugars, leading to the production of reactive oxygen species. This damage occurs especially at the level of cellular proteins, carbohydrates, lipids and DNA, thus playing an important role in the pathogenesis of late complications of T2DM. We investigated the effect of folic acid on DNA and oxidative damage in patients with T2DM.

METHODS

We studied 30 individuals diagnosed with T2DM and 30 control individuals without disease. Individuals with T2DM were prescribed 5 mg of folic acid, taken orally three times daily for 1 month. Samples were taken 15 and 30 days after treatment. DNA damage was determined using the micronucleus test in oral mucosa and oxidative stress by quantifying 8-hydroxy-2'-deoxyguanosine (8-OHdG) as well as by quantifying total lipid peroxides.

RESULTS

Individuals with T2DM had a higher number of micronuclei as well as higher levels of 8-OHdG and lipid peroxides than the control group (p = 0.001). Individuals with T2DM showed a significant reduction in the number of micronuclei and the concentration of 8-OHdG and lipid peroxides over time with folic acid intake.

CONCLUSIONS

A positive correlation exists between oxidative stress produced by T2DM and DNA damage, so the use of an antioxidant such as folic acid in DM2 therapy is advisable for delaying complications due to T2DM-induced oxidative stress and DNA damage.