A Nrf2-OSGIN1&2-HSP70 axis mediates cigarette smoke-induced endothelial detachment: implications for plaque erosion

AIMS

Endothelial erosion of plaques is responsible for ∼30% of acute coronary syndromes (ACS). Smoking is a risk factor for plaque erosion, which most frequently occurs on the upstream surface of plaques where the endothelium experiences elevated shear stress. We sought to recreate these conditions in vitro to identify potential pathological mechanisms that might be of relevance to plaque erosion.

METHODS AND RESULTS

Culturing human coronary artery endothelial cells (HCAECs) under elevated flow (shear stress of 7.5 Pa) and chronically exposing them to cigarette smoke extract (CSE) and tumour necrosis factor-alpha (TNFα) recapitulated a defect in HCAEC adhesion, which corresponded with augmented Nrf2-regulated gene expression. Pharmacological activation or adenoviral overexpression of Nrf2 triggered endothelial detachment, identifying Nrf2 as a mediator of endothelial detachment. Growth/Differentiation Factor-15 (GDF15) expression was elevated in this model, with protein expression elevated in the plasma of patients experiencing plaque erosion compared with plaque rupture. The expression of two Nrf2-regulated genes, OSGIN1 and OSGIN2, was increased by CSE and TNFα under elevated flow and was also elevated in the aortas of mice exposed to cigarette smoke in vivo. Knockdown of OSGIN1&2 inhibited Nrf2-induced cell detachment. Overexpression of OSGIN1&2 induced endothelial detachment and resulted in cell cycle arrest, induction of senescence, loss of focal adhesions and actin stress fibres, and disturbed proteostasis mediated in part by HSP70, restoration of which reduced HCAEC detachment. In ACS patients who smoked, blood concentrations of HSP70 were elevated in plaque erosion compared with plaque rupture.

CONCLUSION

We identified a novel Nrf2-OSGIN1&2-HSP70 axis that regulates endothelial adhesion, elevated GDF15 and HSP70 as biomarkers for plaque erosion in patients who smoke, and two therapeutic targets that offer the potential for reducing the risk of plaque erosion.

Anorexia nervosa: friend or foe?

OBJECTIVE

The aim of this study was to examine anorexics' attitudes towards anorexia nervosa.

METHOD

Anorexic patients were asked to write two letters to their anorexia nervosa, one addressing it as a friend and the other addressing it as an enemy. A coding scheme was developed using a "Grounded Theory" methodology to group recurrent themes. The scheme was used independently by three raters: the first author, a rater with extensive experience in eating disorders, and a novice in the field. Use of the coding scheme showed high interrater reliability and comprehensivess.

RESULTS

Commonly expressed benefits of anorexia nervosa included feeling looked after or protected, gaining a sense of control, and feeling special. Perceived costs of the disorder included constant thoughts about food, feeling taken over, and the damage done to personal relationships.

DISCUSSION

The positive themes found in the letters are important indicators of factors which may maintain anorexia nervosa. The use of the letters to examine these factors has important clinical implications which are outlined.

Neutrophil enzymes in urine for the detection of urethral infection in men

OBJECTIVES

To determine if assaying the neutrophil enzymes, neutrophil elastase (NE) and myeloperoxidase (MPO) in the urine of men attending a genitourinary medicine clinic could identify those with Neisseria gonorrhoeae or Chlamydia trachomatis infections, and those with urethritis (with or without an identified infection with either organism), and to compare the new assays with the performance of the leucocyte esterase test (LET).

METHOD

100 men had urethral specimens taken for Gram-stained urethral smear, culture for N gonorrhoeae, and for C trachomatis testing by enzyme immunoassay. First-voided urines were tested for leucocyte esterase by commercial dipstick (positives were defined as greater than "trace") and then frozen at -20 degrees C prior to being assayed for NE and MPO.

RESULTS

Five patients had gonorrhoea, six had chlamydia and none had both. Evidence of urethritis (> 5 polymorphonuclear leucocytes in four x 1000 fields) was found in 29 men. The results of the urine assays showed MPO levels to be non-discriminatory; however NE levels were significantly elevated in patients with proven infection or urethritis or both. Using NE values from men with no infection or urethritis an upper limit for normal was defined. Utilising this, the sensitivity of the elastase assay was calculated and found to be superior to the sensitivity of LET for detecting proven infection (64% vs 36%) and urethritis (52% vs 31%).

CONCLUSIONS

Further studies of neutrophil elastase in the pathogenesis, diagnosis and treatment of urethritis are indicated.

Immunophenotypic and DNA genotypic analysis of T-cell and NK-cell subpopulations in patients with B-cell chronic lymphocytic leukaemia (B-CLL)

Absolute numbers and distributions of peripheral blood T-cells and NK cells were immunophenotypically determined in 21 patients with B-CLL and compared with those obtained from a series of 13 elderly normal controls with an age range of 60-87 years. For absolute CD3+, CD4+ and CD8+ T-cell, and CD16+ NK subpopulation numbers, there were no consistent differences between the normal and B-CLL groups although some individual patient variation was seen. Immunophenotypic analyses did however reveal that CD3+ T-cells in almost half (10/21) of the B-CLL patients were Ia+ (defined as > 20% positive cells), compared to 0/13 of the elderly control group (p < 0.001), and that the proportions of CD4+ and CD8+ cells expressing membrane CD45RO were significantly increased compared to the control group. Subdivision of the B-CLL cases into those with low (< 20%) and high (> 20%) proportions of CD3+ T-cells co-expressing Ia further showed that CD45RO expression by CD4+ fractions was particularly prominent in the Ia+ subgroup, and that the relative increase of CD4+CD45RO+ cells was primarily a consequence of decreased absolute numbers of CD4+CD45RA+ lymphocytes. This study also examined extracted DNA from enriched CD3+ T-cell fractions (obtained by immunomagnetic bead selection in 9 of the B-CLL cases) by PCR analysis with two primers for the T-cell gamma gene locus. With the V gamma C (consensus) primer, 8/9 cases were polyclonal and the remaining case was oligoclonal. For comparison, 7/9 CD3+ fractions were oligoclonal with the V gamma 9 primer with the other two cases being polyclonal. No monoclonal CD3+ components were found. It is suggested that the observed increased Ia expression by CD3+ cells and the predominance of CD4+ cells expressing membrane CD45RO in patients with B-CLL may be of potential relevance to understanding the pathogenesis and patterns of disease progression.

c-erbB-3 protein expression in human breast cancer: comparison with other tumour variables and survival

c-erbB-3 protein expression was investigated immunohistochemically in a series of 97 malignant breast tumours using the monoclonal antibody RTJ1. Twenty-eight cases (28.8%) showed c-erbB-3 overexpression, 31 cases (32%) showed normal levels of c-erbB-3 and 38 cases (39.2%) were c-erbB-3 negative. c-erbB-3 overexpression was positively but not significantly related to negative lymph node status and survival over a 10-year follow-up period.

Classical oestrogen receptor is not detectable in pancreatic adenocarcinoma

Recent reports have suggested the presence of oestrogen receptors (ER) in pancreatic carcinoma. Therefore the tumour may be sensitive to hormone manipulation therapy. We examined 23 biopsies of human pancreatic carcinoma tissue for the presence of ER. The tissue was assayed by two methods: Iso-electric focusing (IEF) and ER-ICA an immunocytochemical assay. All biopsies were tested with ER-ICA and ten by IEF. Each biopsy was assessed histologically for tumour content and 20 contained adenocarcinoma. None of the samples of pancreatic carcinoma were positive for ER using the ER-ICA, and none demonstrated the binding peak typical of ER in the IEF assay. These results suggest that in pancreatic carcinoma oestrogen receptor is either absent (or at very low levels), or of a different type to that found in breast and uterine tissue. On theoretical grounds at least, this must raise questions as to the oestrogen sensitivity of pancreatic cancer.

Ultrastructural localisation of oestrogen receptor in breast cancer cell nuclei

A method of localising oestrogen receptor in nuclei of breast cancer cells by the protein A-gold technique is described. Mast cell granules were found to take up uncoated particles of the gold sol selectively.

Oestrogen receptor in breast cancer: prognostic studies using a new immunohistochemical assay

A recently developed and validated histochemical method--immunogold-streptavidin enhancement--was used to determine oestrogen receptor content in paraffin sections of breast cancers. The selection of the best cut-off point to define oestrogen receptor status as rich or poor was made on the basis of survival data, using the following indices: survival to term; disease-free interval; survival at 5 years; and disease-free interval at 5 years. Oestrogen receptor status was examined in relation to histological grade, lymph node status, menopausal status and tumour size and these four indices were considered as independent prognostic factors. Semi-quantitative assay of receptor content showed that increasing content was related to better prognosis. Adjuvant therapy alone had no effect on patient outcome. Independently, histological grade and lymph node status, but not menopausal status or tumour size, were prognostic indicators. Oestrogen receptor rich status, as measured by immunogold-streptavidin, in conjunction with certain of these factors indicated a better prognosis. This was comparable with results in reports using other methods of receptor assay. We found the oestrogen receptor status and menopausal status more significant at 5 years than at term. The advantage of immunogold-streptavidin enhancement, which we found as reliable as other methods for oestrogen receptor assay, is that it can be used on archival, routinely paraffin-processed material.

Development and validation of a sensitive immunohistochemical oestrogen receptor assay for use on archival breast cancer tissue

In a preliminary paper (Teasdale et al. 1987) comparing the oestrogen receptor (ER) content of breast cancers by the biochemical dextran coated charcoal (DCC) method and by two histochemical methods, peroxidase immunocytochemistry (ERICA) and immunogold-silver staining (IGSS), it was indicated that ERICA is more sensitive than DCC and that IGSS is as specific as ERICA but less sensitive. This paper describes the comparison of the above three assay methods with two other biochemical methods, iso-electric focusing (IEF) and an enzyme immuno-assay (EIA) on a larger number of cancers. All methods gave statistically comparable results except that IGSS remained less sensitive than the rest. Various modifications to IGSS showed that an immunogold streptavidin enhancement method (IG-SAM) produced sensitivity and specificity equal to that of ERICA. Since IGSS and its modifications are the only methods which can be used on archival paraffin-embedded cancers and IG-SAM gives results highly comparable to ERICA, retrospective studies can be performed on patients whose outcome and response to various treatments are known. Most recent studies have shown that ER positive results can be obtained from 10-year-old paraffin blocks.

Identification of oestrogen receptors in cells of paraffin-processed breast cancers by IGSS

Oestrogen receptor (ER) analysis of breast cancers by the standard dextran coated charcoal (DCC) method and the oestrogen receptor immunocytochemical assay (ERICA), shows that ERICA is more sensitive. We find that the immunogold-silver staining technique (IGSS), which is used on paraffin sections, is applicable to the ERICA antibody and that the DCC and IGSS methods have comparable sensitivity. Reasons for wishing to develop an improved method for oestrogen receptor localisation in paraffin sections and its advantages are given.

Immunocytochemical application of monoclonal antibodies to rat liver glucocorticoid receptor

Seven per cent (10/145) of hybridomas raised against partially purified activated glucocorticoid receptor from rat liver produced monoclonal antibody to receptor. Six IgM secreting clones selected for further investigation bound equally well to activated and non-activated receptor from fresh rat liver, but significantly less well (11-25 per cent) to receptor from frozen rat liver. No interaction was found with oestrogen receptor from rat uterus but extensive cross reaction occurred with progesterone receptor. Although none of the antibodies bound to glucocorticoid receptor from human or porcine liver or lymphoid cells, several cross-reacted with mouse liver glucocorticoid receptor. Immunoelectroblotting of proteins from fresh and frozen rat liver cytosol showed the antibodies bound to 90,000 and 40,000 MW forms of receptor respectively. Immunostaining of both frozen and paraffin embedded sections of rat tissue showed that receptor is preserved during fixation and processing of tissues. Using both indirect immunoperoxidase and immunogold silver staining methods, the pattern of receptor staining observed correlates with the known glucocorticoid responsiveness of the tissues studied.

Physiological and Cytological Similarities between Disease Resistance and Cellular Incompatibility Responses

Excised pea pods responded similarly to both the invasion of plant pathogenic fungi and the presence of bean tissue, bean pollen, and mouse tumor cells by synthesizing pisatin and by developing a characteristic yellow-green fluorescence. Both responses were dependent on RNA and protein synthesis. Conversely, the foreign pollen and incompatible fungi were sensitive to the pea pod tissue and were subject to abnormal development.The induction of pisatin and the yellow-green fluorescence development were mediated by multiple compounds of varying sizes released by fungi or mouse tumor cells. The incompatibility between a bean pathogen, Fusarium solani f. sp. phaseoli, and pea pod tissue was hypothesized to occur as a result of the cross contamination of such inducing compounds.