Apoptotic Cells In Tissue Sections Research Articles

P077 Aberrant Muc1 and Muc13 expression in association with Par polarity complex and Vip dysfunction in a colitis T-cell transfer model

There is emerging evidence that loss of the gastrointestinal mucosal barrier integrity is a significant contributor to the pathophysiology of inflammatory bowel disease (IBD). Mucins represent the major components of the mucus barrier and inappropriate overexpression of transmembrane mucins can affect the barrier integrity by disrupting cell polarity and cell-cell interactions resulting in tight junction dysfunction.1 Aberrant expression of Muc1, Muc4, and Muc13, in particular, is observed in colonic tissue samples of IBD patients.2, 3 Nevertheless, the role of mucins in mucosal barrier disruption in IBD remains elusive. In this study, we investigated the expression patterns of transmembrane mucins and the mediators involved in barrier homeostasis during the progression of colitis in mice. Colitis was induced in immunocompromised SCID mice by the adoptive transfer of CD4+CD25-CD62L+ T cells from the spleens of BALB/c donor mice. At 2, 4, and 6 weeks post-colitis, animals were sacrificed and colonic tissue collected for RNA and protein analysis of membrane-bound mucins (Muc1, Muc4, and Muc13), polarity proteins, and the vasointestinal polypeptide (Vip). This latter protein is implicated in the regulation of tight junction and mucin expression (Hokari et al., 2005). Apoptotic cells in tissue sections were detected using a terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) assay. Our data showed that Muc1 expression was significantly increased after 4 weeks of colitis (Figure a). Interestingly, a significant decrease of Muc13 expression was observed during acute colitis (2 weeks) whereas a remarkable turnover in expression was noted during chronic colitis (4–6 weeks; Figure b). Normal intestinal MUC13 expression plays crucial roles in epithelial proliferation, differentiation and apoptosis but inappropriate overexpression of this mucin could lower the level of protection. Indeed, a higher number of apoptotic cells was seen in tissue of chronic colitis-induced mice (Figure d). Furthermore, the polarity proteins Par3 and aPKC as well as Vip (Figure c) were significantly reduced in expression from week 2 onwards suggesting a disturbance in cell polarity. Relative expression of Muc1 (a), Muc13 (b), Vip (c) in the colon of mice with acute (2w) and chronic (4–6w) colitis. (d) Number of apoptotic cells in healthy and chronic colitis mice. Asterisk indicates significance (one-way ANOVA; p < 0.05). The findings of this study highlight a potential role for Muc1 and Muc13 in mucosal barrier disruption in IBD and the underlying mechanisms involved necessitate further investigation. 1. Kufe D. Mucins in cancer: function, prognosis and therapy. Nat Rev Cancer, 2009. 2. Sheng YH, Lourie R, Lindén SK, et al.. The MUC13 cell-surface mucin protects against intestinal inflammation by inhibiting epithelial cell apoptosis. Gut, 2011. 3. Maaike V, Tim V, Ricard F, et al. Genetic and transcriptomic bases of intestinal epithelial barrier dysfunction in inflammatory bowel disease. Inflamm Bowel Dis. 2017.

An analysis of apoptosis in lymphoid organs and lupus disease in murine systemic lupus erythematosus (SLE).

Apoptosis is a programmed cell death process that helps to regulate both T cell and B cell development. In this study, we have investigated the levels of apoptotic death in cells of the thymuses and spleens (white matter) of autoimmune MRL-lpr/lpr mice with progressive lymphadenopathy and SLE disease activity; we also examined the renal pathology in these animals. Fas is a cell surface receptor, which when activated initiates the sequence of events that lead to apoptosis. In MRL-lpr/lpr mice Fas is defective, so the competency for apoptosis may be reduced. In young animals of advancing age the thymuses enlarged until in 5-month-old females the average weight was three times that at 1 month, and spleen and kidney weights also increased in size disproportionately. At light microscope level apoptotic cells in tissue sections were counted using both routine eosin and haematoxylin staining (to identify them by their morphology) and in situ end-labelling of cells with DNA strand breaks; their presence was further confirmed by electron microscopy. As the mice aged, the numbers of apoptotic cells in thymic cortex, thymic medulla and spleen white pulp areas reduced significantly (P < 0.01-0.001), whereas in BALB/c normal controls they increased significantly (P < 0.05). These changes were coincident with the development of severe lupus, whose activity was assessed by measuring serum anti-ssDNA and anti-dsDNA antibody titres and urinary protein (albumin) level which were elevated significantly by 5 months of age (P < 0.001 for both ssDNA and dsDNA and P < 0.01 for urine albumin) compared with their younger counterparts. Thus, lymphoid organ enlargement, decrease in apoptotic indices, elevated serum anti-ssDNA and anti-dsDNA antibody levels, and impaired renal function coincided with the onset and severity of lupus disease in lpr mice. It seems likely that there is a causal relationship between defective deletion of autoreactive lymphoid cells, imperfect Fas-mediated apoptosis and development of murine SLE.

Increased apoptosis in gastric mucosa adjacent to intestinal metaplasia

Background: The biological processes involved in the development of gastric mucosal atrophy and intestinal metaplasia are still incompletely understood. Reports testing the hypothesis that apoptosis leads to atrophy have yielded...

In situ DNA ligation as a method for labeling apoptotic cells in tissue sections. An overview.

In situ DNA ligation as a method for labeling apoptotic cells in tissue sections. An overview.

Detection of Apoptotic Cells in a Dexamethasone-Induced Thymic Apoptosis Model in Rats Using A Modified Warthin-Starry Silver Impregnation Method to Prevent Fading.

A modified Warthin-Starry (mWS) method was developed to stain apoptotic cells in tissue sections. Essentially the classical WS method is applied except for a minor change to prevent fading. In order to clarify the relationship between mWS-positive cells and apoptosis, apoptotic thymic tissues were examined on the rats treated with dexamethasone. The results clearly showed the distribution of mWS-positive cells to coincide well with that for apoptotic cells observed by terminal deoxynucleotidyl transferase (TdT)-mediated d-UTP-biotin nick end labeling (TUNEL) method. An additional characteristic is that nuclei of mitotic thymocytes, with highly condensed chromatin, are always stained. These observations suggest that the mWS method might be useful and convenient to detect condensed chromatin during apoptosis.

Apoptosis in human embryo development: 1. Cerebral cortex.

We investigated the apoptosis at the beginning of human cerebral cortex development, in the 6th week of embryogenesis, Carnegie stages 16 and 17. Attention was focused on the dorsal wall of the telencephalon to the ventricular zone of proliferation and to the postmitotic zone with beginning of neuronal migration. We identified apoptotic cells in tissue sections by propidium iodide staining, TUNEL and immunohistochemistry for Fas(APO-1/CD95). We determined the distribution and the percentage (reported to the propidium iodide stained nuclei) of apoptotic TUNEL-positive and Fas(APO-1/CD95)-positive cells. TUNEL-positive apoptotic cells in the proliferative zone were 20% in stage 16 and 60% in stage 17. TUNEL-positive apoptotic cells in the postmitotic zone were 8% in stage16 and 30% in stage 17. CD95-positive apoptotic cells in the proliferative zone were 5% in stage 16 and 2% in stage 17. There were no CD95-positive cells in the postmitotic zone. We evidentiated the presence of the suicide receptor Fas(APO-1/CD95) only on a small population of apoptotic neuroblasts in the proliferative zone. The differences between apoptotic distribution and receptors in early corticogenesis suggest that different apoptotic pathways drive the selection of neuronal populations.

Tissue transglutaminase in the small intestine of the mouse as a marker for apoptotic cells. Colocalization with DNA fragmentation.

Besides the morphological changes in cells undergoing apoptosis, such as chromatin condensation and cell shrinkage, histological demonstration of DNA fragmentation by in situ end labeling (ISEL) has been widely used for the demonstration of apoptotic cells in tissue sections. Although DNA fragmentation can be demonstrated in apoptotic cells and apoptotic bodies in most cases, there is no clear correlation of ISEL staining with apoptosis. It has often been demonstrated that, in many morphologically intact cells, nuclei with fragmented DNA can be found. Thus staining with ISEL for the detection of apoptosis is useful only in connection with other markers for apoptosis as, for example, characteristic morphological changes. Here we show that tissue transglutaminase protein is unequivocally expressed in apoptotic enterocytes as shown by DNA fragmentation and morphology. Tissue transglutaminase is not expressed in enterocytes with healthy morphology, although DNA fragmentation can be demonstrated in these cells. Thus the immunohistochemical demonstration of tissue transglutaminase may serve as a simple marker for apoptotic epithelial cells in tissue sections.

TUNEL apoptotic cell detection in tissue sections: critical evaluation and improvement.

TUNEL, i.e., terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling, has become a widely used staining method to assist in detection of apoptotic cells in tissue sections. However, despite its apparent simplicity, this technique has led to considerable disappointment because of its serious limitations in sensitivity and, even more, in specificity. We reviewed the limitations and artifacts of TUNEL and designed a comprehensive protocol to reassess the various procedures in use for five crosslinking and/or precipitating fixatives. By introducing microwave heating in extreme pH-value solutions (pH 3 for formalin and pH 10.6 for Bouin's fixative) coupled with proteolysis, we obtained an intense staining of 70-80% of apoptotic cells and bodies on archival tissue blocks, with little or no background. Owing to the enhanced sensitivity, early stages of apoptosis could be visualized and may enlarge our vision of the apoptotic cell beyond the mere image of shrinkage necrosis. We conclude that TUNEL remains a technique as useful as it is delicate, requiring critical interpretation of the staining. This study points out that, on archival tissues, despite the technical improvements we propose no protocol can be the final answer to all problems. Technique must be readjusted for any variation in tissue processing. However, step-by-step progress has rendered this method not only applicable but also performable within the constraints of archival surgical pathology specimens.

Direct in situ end-labeling for detection of apoptotic cells in tissue sections.

Direct in situ end-labeling for detection of apoptotic cells in tissue sections.

Demonstration of apoptotic cells in tissue sections by in situ hybridization using digoxigenin-labeled poly(A) oligonucleotide probes to detect thymidine-rich DNA sequences.

The recognition of apoptotic cells by morphological appearance alone may be difficult. We have investigated the use of in situ hybridization (ISH) with digoxigenin-labeled poly(A) probes to detect apoptotic cells in tissue sections. This method was compared to conventional morphologic assessment and in situ end-labelling (ISEL) in a range of tissues in which apoptosis is known to occur. ISH with poly(A) probes detected apoptotic nuclei in all tissues in which there was evidence of apoptosis as judged by conventional histology. ISH and, to a lesser extent, ISEL preferentially labeled shrunken but still intact nuclei with margination of chromatin, presumably at an early stage of apoptosis. The poly(A) hybridization was abolished by pretreatment of tissue sections with DNAse. After denaturation of DNA, poly(A) hybridized to nuclei in all cells. No convincing hybridization signal was detected in alcohol-fixed or fresh-frozen sections. Both ISEL and ISH labeled some of the nuclei in ischemic tissues. ISH with poly(A) oligonucleotide probes offers a simple alternative to ISEL for detection of cells in early stages of apoptosis. These probes hybridize to thymidine-rich sequences of DNA in the highly repeated Alu sequences within the nuclear genome. These sequences are believed to become available for hybridization after formalin fixation and paraffin embedding as a result of the apoptosis-related increase in the susceptibility of nuclear DNA to denaturation.

Simultaneous in situ hybridization and TUNEL to identify cells undergoing apoptosis.

Apoptotic cells in tissue sections can be localized by in situ labelling of partly degraded DNA. In a heterogeneous population of cells, however, the specific identity of cell types undergoing apoptosis often cannot be reliably achieved at the light microscope level because of the marked alterations in cellular morphology that characterize apoptosis. In order to clearly specify cell types undergoing apoptosis, in situ end labelling has been coupled to immunohistochemistry. This method is limited by the availability of antibodies that bind to cell-specific protein markers in tissue sections. In contrast, we describe a method that combines in situ end labellin with in situ hybridization, a technique that specifies cell types based on mRNA expression. Taking advantage of the specific expression of surfactant protein C mRNA in type II alveolar epithelial cells, we demonstrate that this technique has the ability to localize alveolar type II cells undergoing apoptosis in vivo after the intratracheal instillation of an antibody that activates the cell surface Fas protein. The wide availability of cell-specific gene markers suggests that this method can be adapted to define cell types that undergo apoptosis during various physiological and pathological states in vivo.

Progesterone withdrawal and RU-486 treatment stimulate apoptosis in specific uterine decidual cells

Progesterone secretion is required for the growth and differentiation of endometrial stromal cells to form decidual cells. For many cells where a growth factor supports cell growth and proliferation, withdrawal of the growth factor initiates apoptosis. This study determined the time course and tissue location of apoptosis in deciduomal tissue after withdrawal of progesterone or injection of the antiprogestin, RU-486. Total DNA was isolated from decidual tissues at intervals after experimental treatments and separated electrophoretically. Internucleosomal DNA fragmentation characteristic of apoptosis was measured by quantitating levels of the 200 bp fragment. Apoptotic cells in tissue sections were detected by direct immunoperoxidase detection of digoxigenin-labeled DNA. Decidual apoptosis reached maximal levels at 12 h after withdrawal of progesterone or injection of RU-486. Increased concentrations of apoptotic cells were observed at the periphery of the growing deciduoma and in the antimesometrial deciduoma near the luminal epithelium after both treatments. These results suggest the withdrawal of progestin initiates apoptosis in cells at the early stages of decidualization.

Counting of apoptotic cells: a methodological study in invasive breast cancer

Aims-To arrive at a reproducible sampling technique for counting apoptotic cells in tissue sections of invasive breast cancer that can serve as a protocol for further clinical studies.Methods-In 4 mum thick haematoxylin and eosin stained tissue sections of 12 breast cancers, apoptotic cells, recognised by strict morphological criteria, were counted in consecutive fields of vision at x1000 magnification in a marked area in the most poorly differentiated region of tumour. These counts were regarded as the gold standard. Subsequently, in a systematic sampling experiment, the number of fields that had to be counted to derive an acceptable coefficient of variation (CV) was determined. To compare counts at different magnifications, all fields of vision were also counted at x630 and x400. The intra- and inter-observer reproducibility was tested by repeated measurements at these magnifications in 10 systematically selected fields of vision.Results-Apoptosis seemed to be a rare event, affecting, on average, about 1% of tumour cells. Noticeable clustering of apoptotic cells was observed. The systematic sampling experiment showed that at x1000 magnification, the CV was improved by counting up to 20 fields. When comparing x400 and x630 magnifications with the x1000 magnification, the correlation coefficients were 0.88 and 0.87, respectively. However, the lower magnifications yielded lower counts. With regard to reproducibility, the intra-observer correlation coefficient was 0.91 at x630 and 0.76 at x400. The inter-observer correlation coefficient was 0.77 at x630 and 0.68 at x400.Conclusions-Apoptotic cells can be counted readily in haematoxylin and eosin stained tissue sections. However, a systematic sampling protocol must be followed and cells should be counted at a relatively high magnification to obtain acceptable reproducibility. The suggested protocol will permit further correlative and prognostic studies and the monitoring of the effects of treatment.

Apoptosis in lactating and involuting mouse mammary tissue demonstrated by nick-end DNA labelling.

Mammary involution after cessation of milk removal is associated with extensive loss of secretory epithelial cells. Ultrastructural changes and the appearance of oligonucleosomal DNA laddering in ethidium bromide-stained gels indicates that cell loss during involution occurs by apoptosis. In this study, a technique for nick end-labelling of genomic DNA with radiolabelled deoxynucleotide has been used to monitor the induction of programmed cell death in mice after litter removal at peak lactation. This technique proved more sensitive than conventional ethidium bromide staining, and results suggested that apoptosis was induced rapidly by milk stasis, before extensive tissue re-modelling had begun. Oligonucleosomal DNA laddering on agarose gels was detected within 24 h of milk stasis, and increased progressively for at least 4 days. Nick-end labelling also detected laddering before litter removal, suggesting that programmed cell death is a normal feature of the lactating tissue. The DNA end-labelling technique was also adapted for in situ visualisation of apoptotic cells in tissue sections. By this criterion, apoptotic cells were identified in both the secretory epithelium lining the alveoli of the gland and, increasingly with prolonged milk stasis, amongst those sloughed into the alveolar lumen. The results demonstrate the utility of these techniques for study of mammary cell death and suggest that, whilst apoptosis is rapidly induced by milk stasis, it is also a normal physiological event in the lactating mammary gland.

Ultrastructural detection of DNA strand breaks in apoptotic neural cells by in situ end-labelling techniques.

Recently developed techniques based on 'in situ end-labelling' (ISEL) of DNA strand breaks may help to identify apoptotic cells in tissue sections. We have applied ISEL techniques at the electron microscopic (EM) level, in order to verify if ultrastructural features of apoptosis are indeed associated with evidence of DNA fragmentation, and whether cells committed to, but which have not yet entered the stage of cell death are also labelled. Terminal transferase and DNA polymerase assays were applied to thin sections of Araldite and LR Gold-embedded medulloblastomas and embryonic mouse dorsal root ganglia. Digoxigenin-labelled nucleotides were used; incorporation was demonstrated by immunogold staining. Apoptotic cells in various stages of the death process were easily labelled in both tissues. In addition, DNA fragmentation was demonstrated in cells with initial chromatin condensation, but otherwise indistinguishable from adjacent unstained cells. Our results show that EM-ISEL techniques effectively demonstrate the occurrence of DNA strand breaks in apoptotic and possibly 'pre-apoptotic' cells in neural tissues. Since the labelling is easily obtained on tissue that is routinely processed for electron microscopy, this technique may allow retrospective studies on archival material.