Influence of Body Mass Index and Duration of Disease on Chromosome Damage in Lymphocytes of Patients with Diabetes

It is well-established that patients with diabetes mellitus (DM) have a higher incidence of several types of cancer. The precise mechanisms of this association are still unknown, but obesity and chronic inflammation-induced reactive oxygen species (ROS) are thought to be the main risk factors. ROS may produce different DNA damage, which could eventually lead to cancer. The main objective of this study was to evaluate the relation of chromosome aberrations (CA) with disease status, demographics, and clinical parameters in 33 subjects with type 1 DM (T1DM), 22 subjects with type 2 DM (T2DM), and 21 controls. CAs were analyzed in cultured peripheral blood lymphocytes and subdivided into chromatid (CTA)- and chromosome (CSA)-type aberrations. Compared with controls, higher levels of CTAs and CSAs were observed in T1DM (p = 0.0053 and p = 0.0203, respectively) and T2DM (p = 0.0133 and p = 0.00002, respectively). While there was no difference in CTAs between T1DM and T2DM, CSAs were higher in T2DM (p = 0.0173). A significant positive association between CTAs and disease duration (rs = 0.2938, p = 0.0099) and between CSAs and disease duration (rs = 0.4306, p = 0.0001), age (rs = 0.3932, p = 0.0004), and body mass index (BMI) (rs = 0.3502, p = 0.0019) was revealed. After multiple regression analysis, duration of disease remained significant for CTA, CSA, and CAs (p = 0.0042, p = 0.00003, and p = 0.00002, respectively). For CSA, BMI and the use of statins were the other important confounding variables (p = 0.0105 and p = 0.0763). Thus, this study demonstrated that both T1DM and T2DM patients had a higher number of all types of aberrations than controls, which increases with the prolonged disease duration. Higher BMI was associated with a higher frequency of CSA. The use of statins might be beneficial for reducing chromosome damage, but further investigations are needed to confirm this association.

Iron supplementation does not aggravate impaired glucose tolerance and sugar overload-induced genotoxicity in rats

High sugar intake is a major risk factor for metabolic disorders. Genotoxicity is an important factor in diabetes onset, and iron (Fe) may be an aggravating element. However, this relationship is still poorly established. Thus, this study evaluated whether Fe supplementation could aggravate obesity, impaired glucose tolerance, and sugar overload-induced genotoxicity in rats. A total of 24 rats were treated with different diets: standard diet (SD, n = 8), invert sugar overload (320 g/L, HSD, n = 8), or Fe plus invert sugar overload (2.56 mg/L of Fe²⁺, Fe-HSD, n = 8) for four months. After treatment, the Fe-HSD group showed no excessive weight gain or impaired glucose tolerance. DNA damage in blood, as assessed by comet assay, gradually increased in HSD during treatment (p < 0.001), whereas Fe-HSD showed a nonlinear increase in DNA damage. Moreover, Fe-HSD presented 0.6-fold more DNA damage compared with SD (p = 0.0055) in the 1st month of treatment. At months 2 and 3, results show a ≥ 1.4-fold increase in HSD and Fe-HSD DNA damage, respectively, compared with SD (p < 0.01). At the end of the experiment, only HSD DNA damage differed from SD (1.5-fold more, p = 0.0196). Fe supplementation did not aggravate the invert sugar-induced DNA damage (p > 0.05). In the pancreas, results showed no differences in DNA damage. Mutagenicity, evaluated by micronucleus testing, was not observed regardless of treatment (p = 0.428). Fe supplementation, in the evaluated concentration, did not aggravate weight gain, impaired glucose tolerance, and sugar overload-induced genotoxicity in rats.

Buccal micronucleus cytome assay in children living in an area with low anthropogenic pressure: The EFFE.BI.P. study

The study aimed to evaluate the micronucleus (MN) frequency in exfoliated buccal cells (EBCs) of 256 6-8-years-old schoolchildren living in a rural area of Salento peninsula (Southern Italy) with low anthropogenic pressure and with a normal rate of chronic diseases in order to determine the basal level of MN and identify which factors are able to influence it. Information about the personal data, lifestyles and dietary habits of the children were obtained by the administration of a questionnaire to their parents. The buccal micronucleus cytome assay was performed to evaluate the presence of early genotoxic effects among the children. In addition, the level of environmental exposure was assessed by sampling atmospheric particulate fractions near the schools attended by participants. The association between MN frequency and individual or environmental factors was also assessed. The children had a mean MN frequency of 0.27 ± 0.43‰ (95%CI = 0.22-0.33). This frequency was positively associated with vehicular traffic (OR = 2.99; 95%CI = 1.15-7.74) and negatively associated with a high educational level of the mother (OR = 0.41; 95%CI = 0.18-0.95) and physical exercise (OR = 0.56; 95%CI = 0.32-0.57). Data on genotoxic effects in buccal cells found in this study could be considered as the MN level in a pediatric population not exposed to environmental pollution.

Impact of dietary and lifestyle interventions in elderly or people diagnosed with diabetes, metabolic disorders, cardiovascular disease, cancer and micronutrient deficiency on micronuclei frequency - A systematic review and meta-analysis

Chronic diseases such as cardiovascular diseases, type 2 diabetes or cancer are the global leading cause of mortality. Lifestyle interventions are most effective in reducing metabolic risk factors, disease progression or even side effects of a disease. They are also contributing to decelerate the aging process. Genome instability is very often associated with aging or the above-mentioned diseases, and triggered by inflammation and oxidative stress. An established method to measure chromosomal damage is the cytokinesis block micronucleus (CBMN) cytome assay. The aim of this review and meta-analysis is to collect and analyse the current literature regarding the effects of a lifestyle based (dietary) intervention on changes of micronuclei (MNi), nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs) in elderly subjects or people diagnosed with diabetes, metabolic disorders, cardiovascular disease, cancer or micronutrient deficiency. Although the main important diseases were considered as well as the large topic of aging, the number and methodological quality in terms of samples size, duration and rationale of the intervention or an inclusion of a control group of available intervention studies with these backgrounds was low. Most of the studies used antioxidant vitamins or folate, few investigated the whole diet. Only one study showed a physical activity intervention approach. The interventions did not lead to decreased genomic marker despite a few cancer related studies, where particularly MN frequency in mucosa lesions and leukoplakia was reduced by green tea and antioxidants. The performed meta-analysis of the available RCTs did not show a significant reduction of MNi, NBUDs or NPBs of most of the interventions performed, except for green tea. Data show in general a lack of an appropriate number of sound lifestyle based intervention studies linking cytogenetic damage and chronic diseases.

Micronucleus frequency in chronic kidney disease patients: A review

BACKGROUND

Chronic kidney disease (CKD) is defined as a gradual loss of renal function progressing from very mild damage, with no obvious symptoms in stage one, to complete kidney failure in stage five, which ultimately requires kidney replacement therapy by organ transplantation or dialysis. Cancer incidence and other health problems, mainly diabetes and hypertension, are elevated in CKD, ultimately leading to elevated mortality.

METHODS

A literature search on the induction of micronuclei (MN) as endpoint for genomic damage in white blood cells and buccal mucosa cells of CKD patients was conducted. Possible associations with disease stage, treatment modalities, and vitamin or antioxidant supplementations were analyzed.

RESULTS

In total, 26 studies were enclosed in the data analysis. Patient groups in the predialysis or hemodialysis state of the disease exhibit higher levels of genomic damage, measured as micronucleus frequency in peripheral blood lymphocytes and buccal mucosa cells, than healthy control groups. Genomic damage seems to increase with the disease stage during the predialysis phase. The association with dialysis regimens or with years on dialysis is less clear, but there are indications that efficient removal of uremic toxins is beneficial. Patients with CKD receive a variety of medications, some of which could modulate genomic damage levels and thus contribute to the observed heterogeneity. In addition, supplementation with vitamins or antioxidants may in some cases lower the genomic damage. Meta-Analysis confirmed the high and significant levels of genomic damage present in CKD patients compared to matched healthy controls.

CONCLUSION

Genomic damage, as measured by the MN frequency, is elevated in CKD patients. Different strategies, including supplementation with antioxidants and optimizing dialysis processes, can reduce the levels of genomic damage and the different associated pathologies. Whether MN frequency can in the future also be used to assist in certain therapeutic decisions in CKD will have to be investigated further in larger studies.

Micronucleus assay for predicting coronary artery disease: A systematic review and meta-analysis

Coronary artery disease (CAD) is the leading cause of morbidity and mortality worldwide. Coronary angiography allows an accurate assessment of the extent and severity of atherosclerotic coronary narrowing, but it provides little characterization of early detection of potentially asymptomatic vulnerable plaque. The identification of the coronary "vulnerable patient" or high-risk plaques remains a major challenge in the treatment of CAD. Recently, growing evidence shows that DNA damage plays a role in the initiation and progression of atherosclerotic plaque. Cytokinesis-block micronucleus (CBMN) assay is one of the most frequently used and validated method for assessing chromosomal damage and genetic instability. Accordingly, the purpose of this systematic review was to retrieve and discuss existing literature on the studies assessing the association between MN and angiographically-proven CAD. A total of 8 studies published between 2001 and 2017 were included in the meta-analysis. Despite a large heterogeneity between studies (I²= 99.7 %, p < 0.0001), an overall increase of MN frequencies was found in patients with CAD compared with control group (meta-MR = 1.96; 95 % CI, 1.5-3.2, p = 0.009). A subgroup analysis showed an increase in the frequency of MN formation for both two- vessel (MR = 2.13, 95 % CI: 0.9-6.9, p = 0.08) and three-vessel disease (MR = 2.89, 95 % CI: 1.84-4.55, P = 0.06). Overall, the results of this meta-analysis provide evidence of an association between CBMN and presence, extent and severity of angiographically-assessed CAD. However, the small number of papers analyzed requires further large and more rigorously designed studies, carefully considering a series of clinical confounding factors, such as the quality of the metabolic control, the influence of drugs and radiation imaging treatments.

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.

Jatrophane Diterpenoids With Protective Effect on Human Lymphocytes DNA

Two sets of structurally different jatrophanes (1-11 and 13-16), jatrophane 12, and latex extract of 2 Euphorbia species (17 and 18) were tested for in vitro protective effect against chromosome aberrations in peripheral human lymphocytes using the cytokinesis-block micronucleus (CBMN) assay. Jatrophanes 1-6 in minimal doses of 1 µg/mL prominently decreased micronuclei (MN) frequency in the range 44.86% to 34.29% and manifested considerable protective effect. From the other set of jatrophanes, 13 in the same minimal dose notably decreased MN frequency by 31.05%, while extracts 17 and 18 at a concentration of 4 µg/mL remarkably decreased the frequency of MN by 37.94% and 36.12%, respectively. Jatrophanes 12, 14, and 16 showed moderate protection, while 7-11 and 15 were less active than positive control. The structure-activity relationship (SAR) studies of the tested jatrophanes (1-16) indicated the favorable position of benzoate at C-8 or C-9 (3, 4, and 13) and a preference of isobutanoyloxy group at C-3 (1-3) rather than propanoyloxy at the same position (4-6) for pronounced protective effect on human lymphocytes DNA. In a previous SAR study on 11 jatrophanes (1, 3-8, and 13-16), the same structural features in 3, 4, and 13 influenced powerful inhibition of P-gp, while growth inhibition of cancer cells was more than doubled in 1 (isobutanoyloxy group at C-3) compared to 6 (propanoyloxy at C-3).

The molecular origins and pathophysiological consequences of micronuclei: New insights into an age-old problem

Micronuclei (MN), the small nucleus-like bodies separated from the primary nucleus, can exist in cells with numerical and/or structural chromosomal aberrations in apparently normal tissues and more so in tumors in humans. While MN have been observed for over 100 years, they were merely and constantly considered as passive indicators of chromosome instability (CIN) for a long time. Relatively little is known about the molecular origins and biological consequences of MN. Rapid technological advances are helping to close these gaps. Very recent studies provide exciting evidence that MN act as key platform for chromothripsis and a trigger of innate immune response, suggesting that MN could affect cellular functions by both genetic and nongenetic means. These previously unappreciated findings have reawakened widespread interests in MN. In this review, the diverse mechanisms leading to MN generation and the complex fate profiles of MN are discussed, together with the evidence for their contribution to CIN, inflammation, senescence and cell death. Moreover, we put this knowledge together into a speculative perspective on how MN may be responsible for cancer development and how their presence may influence the choice of treatment. We suggest that the heterogeneous responses to MN may function physiological to ensure the arrestment, elimination and immune clearance of damaged cells, but pathologically, may enable the survival and oncogenic transformation of cells bearing CIN. These insights not only underscore the complexity of MN biology, but also raise a host of new questions and provide fertile ground for future research.

Association of Elevated Peripheral Blood Micronucleus Frequency and Bmi-1 mRNA Expression with Metastasis in Iranian Breast Cancer Patients

Background:

In order to find cytogenetic and molecular metastasis biomarkers detectable in peripheral blood the spontaneous genomic instability expressed as micronuclei and Bmi-1 expression in peripheral blood of breast cancer (BC) patients were studied in different stages of the disease compared with unaffected first-degree relatives (FDRs) and normal control.

Methods:

The Cytokinesis Block Micronuclei Cytome (CBMN cyt) and nested real-time Reverse Transcription-Polymerase Chain Reaction (RT-PCR) assays, were respectively used to measure genomic instability and Bmi-1 gene expression in 160 Iranian individuals comprised of BC patients in different stages of the disease, unaffected FDRs and normal control groups.

Result:

The frequency of micronuclei and Bmi-1 expression were dramatically higher in distant metastasis compared with non-metastatic BC. In spite of micronucleus frequency with no association with lymph node (LN) involvement and hormone receptor status, the Bmi-1 expression level was higher in LN positive and triple negative patients.

Conclusion:

Our results indicate that increased genomic instability expressed as micronuclei and higher Bmi-1 expression in peripheral blood are associated with metastasis in breast cancer. Therefore implementation of micronucleus assay and Bmi-1 expression analysis in blood as possible cytogenetic and molecular biomarkers in clinical level may potentially enhance the quality of management of patients with breast cancer.

Increased Micronuclei Frequency in Oral and Lingual Epithelium of Treated Diabetes Mellitus Patients

Diabetes mellitus (DM) is a metabolic disease characterized by persistent high levels of glucose in plasma. Chronic hyperglycemia is thought to increase oxidative stress and the formation of free radicals that in turn damage cells. Thus, we decided to determine the frequency of nuclear abnormalities in epithelial cells from cheek and tongue mucosa of DM patients with type 1 (DM1, treated only with insulin) and type 2 (DM2, treated with metformin) using the buccal micronucleus cytome (BMCyt) assay. Micronuclei frequency in cheek epithelial cells was higher in both DM1 (0.75 ± 0.31, P < 0.001) and DM2 (0.52 ± 0.27, P < 0.001) patients, as compared to healthy controls (0.07  ±  0.06). Similarly, micronuclei frequency in tongue epithelium was increased in DM1 (0.81  ±  0.22, P < 0.001) and DM2 (0.41  ±  0.21, P < 0.001) groups, in comparison to controls (0.06  ±  0.05). Besides, we found a positive correlation between micronuclei frequency and the onset time of DM2 in both cheek (ρ = 0.69, P < 0.001) and tongue epithelial cells (ρ = 0.71, P < 0.001), but not with onset time of DM1 or age of the patients. Considering all this, we pose that BMCyt could serve as a fast and easily accessible test to assess genotoxic damage during dental visits of DM patients, helping to monitor their disease.

In vitro cytotoxic and genotoxic evaluation of peptides used in nuclear medicine (DOTATATE and Ubiquicidin29-41) in CHO-K1 cells

Micronucleus (MN) assay constitutes a valuable surrogate to the chromosome aberration technique for in vitro testing of the genotoxicity of substances. As test substances, two peptidic compounds (DOTATATE and Ubiquicidin_29-41) used in nuclear medicine, were tested for in vitro cytotoxicity and genotoxicity in CHO-K1 cells. None of the compounds showed detectable cytotoxicity (0.5-7.3 ng/mL for DOTATATE and 0.3-4.5 ng/mL for UBI_29-41), genotoxicity (0.72, 7.2 and 72.0 ng/ml for DOTATATE and 0.45, 4.5 and 45.0 ng/mL for UBI_29-41) or cell cycle changes as compared to untreated controls at the concentrations tested. Statistical analysis showed good concordance between two independent analysts. The results corroborate the notion of the safety of the compounds and present improvements of the in vitro MN assay when performed in a pre-clinical trial context that increase the throughput of small-to-medium testing facilities as an alternative to high content screening systems.