Increased inflammatory low-density neutrophils in severe obesity and effect of bariatric surgery: Results from case-control and prospective cohort studies

BACKGROUND

Low-density neutrophils (LDN) are increased in several inflammatory diseases and may also play a role in the low-grade chronic inflammation associated with obesity. Here we explored their role in obesity, determined their gene signatures, and assessed the effect of bariatric surgery.

METHODS

We compared the number, function, and gene expression profiles of circulating LDN in morbidly obese patients (MOP, n=27; body mass index (BMI) > 40 Kg/m²) and normal-weight controls (NWC, n=20; BMI < 25 Kg/m²) in a case-control study. Additionally, in a prospective longitudinal study, we measured changes in the frequency of LDN after bariatric surgery (n=36) and tested for associations with metabolic and inflammatory parameters.

FINDINGS

LDN and inflammatory markers were significantly increased in MOP compared to NWC. Transcriptome analysis showed increased neutrophil-related gene expression signatures associated with inflammation, neutrophil activation, and immunosuppressive function. However, LDN did not suppress T cells proliferation and produced low levels of reactive oxygen species (ROS). Circulating LDN in MOP significantly decreased after bariatric surgery in parallel with BMI, metabolic syndrome, and inflammatory markers.

INTERPRETATION

Obesity increases LDN displaying an inflammatory gene signature. Our results suggest that LDN may represent a neutrophil subset associated with chronic inflammation, a feature of obesity that has been previously associated with the appearance and progression of co-morbidities. Furthermore, bariatric surgery, as an efficient therapy for severe obesity, reduces LDN in circulation and improves several components of the metabolic syndrome supporting its recognized anti-inflammatory and beneficial metabolic effects.

FUNDING

This work was supported in part by grants from the National Institutes of Health (NIH; 5P30GM114732-02, P20CA233374 - A. Ochoa and L. Miele), Pennington Biomedical NORC (P30DK072476 - E. Ravussin & LSU-NO Stanley S. Scott Cancer Center and Louisiana Clinical and Translational Science Center (LACaTS; U54-GM104940 - J. Kirwan).

Tracking pathogen transmission at the human-wildlife interface: banded mongoose and Escherichia coli

A primary challenge to managing emerging infectious disease is identifying pathways that allow pathogen transmission at the human-wildlife interface. Using Escherichia coli as a model organism, we evaluated fecal bacterial transmission between banded mongoose (Mungos mungo) and humans in northern Botswana. Fecal samples were collected from banded mongoose living in protected areas (n = 87, 3 troops) and surrounding villages (n = 92, 3 troops). Human fecal waste was collected from the same environment (n = 46). Isolates were evaluated for susceptibility to 10 antibiotics. Resistant E. coli isolates from mongoose were compared to human isolates using rep-PCR fingerprinting and MLST-PCR. Antimicrobial resistant isolates were identified in 57 % of the mongoose fecal samples tested (range 31-78% among troops). At least one individual mongoose fecal sample demonstrated resistance to each tested antibiotic, and multidrug resistance was highest in the protected areas (40.9%). E. coli isolated from mongoose and human sources in this study demonstrated an extremely high degree of genetic similarity on rep-PCR (AMOVA, F ST = 0.0027, p = 0.18) with a similar pattern identified on MLST-PCR. Human waste may be an important source of microbial exposure to wildlife. Evidence of high levels of antimicrobial resistance even within protected areas identifies an emerging health threat and highlights the need for improved waste management in these systems.

Genetic research on rare familial disorders: consent and the blurred boundaries between clinical service and research

OBJECTIVES

To study the consent process experienced by participants who are enrolled in a molecular genetic research study that aims to find new genetic mutations responsible for an apparently inherited disorder.

DESIGN

Semi-structured interviews and analysis/description of main themes.

PARTICIPANTS

78 members of 52 families who had been recruited to a molecular genetic study.

RESULTS

People were well informed about the goals, risks and benefits of the genetic research study but could not remember the consent process. They had mostly been recruited to take part by trusted clinicians or their relatives but had little memory of, or concern about signing consent forms. Families appeared to regard the research as a continuation of their, or their relatives', clinical care.

CONCLUSIONS

Ethical review should be more flexible in its attitude to consent forms and written information sheets for some sorts of research. For rare genetic disease studies where research has been discussed fully within the clinical setting then the consent obtained at that time could suffice rather than needing extra consent at a later stage. However, clinician-researchers will need to ensure that their duty of care extends for the duration of the research and beyond.

A prospective study of neurofibromatosis type 1 cancer incidence in the UK

Neurofibromatosis type 1 (NF1) is an autosomal dominant condition affecting around one in 3000 live births. The manifestations of this condition are extremely variable, even within families, and genetic counselling is consequently difficult with regard to prognosis. Individuals with NF1 are acknowledged to be at increased risk of malignancy. Several studies have previously attempted to quantify this risk, but have involved relatively small study populations. We present prospective data from 448 individuals with NF1 with a total of 5705 years of patient follow-up. These data have been collected via the UK NF1 association for patients. Demographic information on the affected individuals was cross-referenced with UK cancer registry data by the UK Office of National Statistics. The overall risk of cancer was 2.7 times higher in this cohort of NF1 patients than in the general population (95% confidence interval (CI) 1.9–3.7). The cumulative risk of a malignancy by age 50 years was 20% (95% CI 14–29%); beyond this age, the risk of cancer was not significantly elevated (P=0.27). The most frequent types of cancer were connective tissue (14% risk by age 70, 95% CI 7.8–24%) and brain tumours (7.9, 95% CI 3.9–16%). There was no statistically significant excess of cancers at other sites (P=0.22).

JUST in time health emergency interventions: an innovative approach to training the citizen for emergency situations using virtual reality techniques and advanced IT tools (the VR Tool)

This paper reports the results of the second of the two systems developed by JUST, a collaborative project supported by the European Union under the Information Society Technologies (IST) Programme. The most innovative content of the project has been the design and development of a complementary training course for non-professional health emergency operators, which supports the traditional learning phase, and which purports to improve the retention capability of the trainees. This was achieved with the use of advanced information technology techniques, which provide adequate support and can help to overcome the present weaknesses of the existing training mechanisms.

Issues of consent and feedback in a genetic epidemiological study of women with breast cancer

Women (N=21) who had had breast cancer and had been enrolled in a large genetic breast cancer epidemiological study were interviewed about their experience of participation in the study, their attitudes to the confidentiality of data, and the feedback of personal and general research results. Collection of family history information seemed more salient in indicating the genetic nature of the study than the enrolment information sheet. There were no concerns about confidentiality. While participants would have welcomed general feedback about the results of the study and were critical that this had not been provided, the feedback of personal information proved complicated and, sometimes, difficult. It is suggested that individual feedback of genetic test information in epidemiological studies should be undertaken only when there are specific reasons.

Gross deletions of the neurofibromatosis type 1 (NF1) gene are predominantly of maternal origin and commonly associated with a learning disability, dysmorphic features and developmental delay

Mutation screening in neurofibromatosis type 1 (NF1) families has long been hampered by the complexity of the NF1 gene. By using a novel multi-track screening strategy, 67 NF1 families (54 two-generation, 13 three-generation) with a de novo mutation in the germline of the first generation were studied with two extragenic and 11 intragenic markers. The pathological lesion was identified in 31 cases. Loss of heterozygosity (LOH) in the affected individual revealed a gross gene deletion in 15 of the two-generation families; in 12 (80%) of them, the deletion was maternally derived. Eleven patients with a gross deletion exhibited developmental delay, ten had dysmorphic features and six manifested a learning disability. No gross deletion was apparent in any of the 13 three-generation families, suggesting that such lesions are subject to more intense selection. In these families, the new mutation was of paternal origin in 11 kindreds and the underlying mutational event could be characterised in three of them.

Spinal and cutaneous schwannomatosis is a variant form of type 2 neurofibromatosis: a clinical and molecular study

OBJECTIVE

To delineate the clinical phenotype, molecular basis, and implications for screening in patients and families with multiple schwannomas not generally involving the cranium.

METHODS

As part of a United Kingdom clinical and genetic study of type 2 neurofibromatosis (NF2) patients and families with multiple schwannomas who do not fulfil diagnostic criteria for NF2 have been identified. The clinical phenotype was studied in the extended families and molecular analysis was carried out at the NF2 gene locus on chromosome 22.

RESULTS

Patterns of inheritance in five families with schwannomatosis are consistent with inheritance of an autosomal dominant gene. The consistency of phenotype, with relative sparing of the cranium, is constant in these families. However, families which initially seem to be indicative of schwannomatosis may develop into classic NF2 as shown by a sixth family. Many of the tumours found in these families were referred to as "neurofibroma" when they were clearly schwannomas. This difference in classification has major implications for the relative risk of each particular type of neurofibromatosis and neuropathological review may be important in some cases. Genetic linkage analysis in the two largest families is entirely consistent with primary involvement of the NF2 gene.

CONCLUSIONS

Variant forms of neurofibromatosis have presented a dilemma in classification and determination of recurrence risks in families. Previous reports have suggested that schwannomatosis is a sporadic non-hereditary condition. Patients with multiple schwannomas are likely to have a variant form of NF2 and up to a 50% risk of passing on a gene predisposing to multiple schwannoma.

Lay understanding of genetics: a test of a hypothesis

There have been growing calls for more education in genetics for the public and in schools. However, studies of the public, school children, and those who have received genetic counselling show that understanding of scientific genetics is very limited. A hypothesis to explain this limited understanding is proposed and tested. It is argued that there is a widespread lay knowledge of inheritance which conflicts in a number of aspects with scientific explanations and which impedes the assimilation of the latter. It is suggested that this lay knowledge is derived from concepts of the social relationships of kinship. Concepts of kinship ties are sustained by everyday social activities and relationships which may make them resistant to change. A prediction which follows from the hypothesis that the lay understanding of genetics is derived from concepts of family and kinship relationships is that closeness in genetic terms will be determined by the closeness of the family ties of social relationship and social obligation. While the proportion of genes shared with parents, children, and sibs is, on average, the same, kin relationships and obligations are much stronger between parents and children than between sibs. The hypothesis was tested in a questionnaire study of two samples of adult women (n = 64 and n = 113) and one of social science students (n = 73). In all three groups a higher proportion of subjects gave the correct response for the proportion of shared genes with a father and child than with a sister, uncle, or grandmother. In the cases of sisters and uncle (and grandmother), there was a consistent tendency to underestimate the degree of genetic connection as predicted by the hypothesis. Answers to other questions are consistent with the hypothesis. The fundamental implications of the hypothesis for genetic education in the clinic and classroom are outlined.

Family history and perceived vulnerability to some common diseases: a study of young people and their parents

During the last two decades, health promotion has concentrated on lifestyle factors. However, recent research in genetics has shown that inherited susceptibility may be important in many common conditions. This raises questions about how these two different messages are integrated into people's beliefs about their own susceptibility. We report a study based on interviews with 58 young people, who had all recently completed the National Curriculum science course including basic human genetics, and 54 of their parents. We aimed to examine the extent to which people take account of family history when considering their susceptibility to health risks, with comparisons being made between generations, gender, and between different diseases. Family health histories were compared between generations and the relationship between reported family history and perceived vulnerability was examined. Family health history was seen as more relevant for a perceived vulnerability to heart disease and diabetes than cancer, while actions and behaviour were seen as important in determining the chance of developing heart disease and cancer but less so for diabetes. Chance was seen as an important factor in the risk of cancer and diabetes, but was barely mentioned in connection with heart disease. Nearly half of those who reported affected family members with heart disease or cancer did not perceive this to have any effect on their own susceptibility. Notably, women were much more likely than men to see the presence or absence of affected relatives as being relevant to the chances of developing cancer. Differences were found between generations in the reporting of the family tree and in knowledge of health of family members. Although words such as genes, chromosomes, and DNA were used by both generations there was no evidence of any understanding of the process of inheritance in scientific terms.

Characterisation of germline mutations in the neurofibromatosis type 1 (NF1) gene

Neurofibromatosis type 1 is one of the most common inherited disorders with an incidence of 1 in 3000. The search for NF1 mutations has been hampered by the overall size of the gene, the large number of exons, and the high mutation rate. To date, fewer than 90 mutations have been reported to the NF1 mutation analysis consortium and the details on 76 mutations have been published. We have identified five new mutations using single strand conformation polymorphism (SSCP) and heteroduplex analysis (HA) and three intragenic deletions with the microsatellite markers. Of the five new mutations, two were in exon 27a, two in exon 45, and one in exon 49 and these include 4630delA, 4572delC, R7846X, T7828A, and one in the 3' untranslated region (3' UTR). The two nucleotide alterations in exon 27a and the one in exon 45 are predicted to produce a truncated protein.

Direct, non-radioactive detection of mutations in multiple endocrine neoplasia type 2A families

We have designed PCR primers that permit the rapid non-isotopic detection of mutations in codon 634 of the RET proto-oncogene, the causative mutations in over 80% of MEN 2A and 50% of FMTC families. In this paper we report the investigation of eleven MEN 2A families referred to the East Anglian Regional Genetics Service. Nine of these families carry codon 634 mutations. We were able to confirm the diagnosis of MEN 2A in twenty six affected individuals and to determine the carrier status of forty one individuals thought to be at risk of developing the disease. Of those at risk, thirty one patients lacked the familial mutation and ten were presymptomatic carriers of MEN 2A. In five cases the direct test proved that patients who had been treated by thyroidectomy but who lacked confirmed cancer, did not carry the familial mutation, removing the perceived risk of MEN 2A from their children. This group included one patient who had been diagnosed as having mild C-cell hyperplasia, confirming that in MEN 2A families C-cell hyperplasia can result from causes other than the presence of the MEN 2A mutation.

Genetic heterogeneity and localization of a familial breast-ovarian cancer gene on chromosome 17q12-q21

In a study of 31 breast cancer families and 12 breast-ovarian cancer families, we have obtained clear evidence of linkage to markers on chromosome 17q in the families with ovarian cancer (maximum lod score 3.34 at theta = .04) but only weak evidence in those without ovarian cancer. Recombinant events indicate that the gene lies between D17S588 and D17S250.

Molecular analysis of neurofibromatosis type 1 mutations

We have examined a panel of 115 unrelated NF1 individuals for mutation in the 3' region of the NF1 gene, using Southern blotting and polymerase chain reaction amplification of exons followed by single-strand conformation polymorphism (SSCP) analysis. We found only 2 unequivocal mutations: a 571 bp deletion which removed exon 6 and resulted in a frameshift in exon 7, and a 2 bp deletion in exon 1. A third sequence variation detected by SSCP was predicted to cause a lysine-arginine substitution in exon 6. This is a conservative change, and since the affected individual is a new mutation whose parents are not available, we cannot be sure of its biological significance. We detected mutations in at most 3% of individuals, from an analysis which covered 17% of the coding sequence by SSCP and a larger region by Southern blotting. This relative failure to detect mutations accords with the experience of others. Even allowing for the incomplete sensitivity of the methods used, the results suggest that the majority of NF1 mutations lie elsewhere in the coding sequence or outside it.

A TaqI polymorphism in the human NF1 gene

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Linkage analysis of chromosome 17 markers in British and South African families with neurofibromatosis type I

Nine markers from the pericentromeric region of chromosome 17 were typed in 16 British and five South African families with neurofibromatosis type 1 (NF1). The markers--p17H8, pHHH202, and EW204--were linked to NF1 at recombination fractions less than 1%. No evidence of locus heterogeneity was detected. Inspection of recombinant events in families informative for several markers suggests that the NF1 gene is located between the markers EW301 (cen-p11.2) and EW206 (cen-q12) and possibly distal to pHHH202 (q11.2-q12).