Is apoptosis involved in mechanisms to eliminate Onchocerca ochengi during Simulium damnosum s.l. immune response?

Co-injection of the parasite Onchocerca ochengi and the caspase inhibitors z-VAD.fmk and boc-D.fmk into the natural vector Simulium damnosum s.l. led to significantly increased survival of the parasites. Subsequent in situ apoptosis detection assays demonstrated that in the case of boc-D.fmk the enhanced survival was due to a diminished apoptosis level of the microfilariae in vivo. Additional assays using O. ochengi microfilariae which were coinjected with serine protease inhibitors into S. damnosum s.l. revealed that certain serine protease inhibitors can reduce the level of apoptosis.

Increased stem cell somatic mutation in the non-neoplastic colorectal mucosa of patients with familial adenomatous polyposis

Colorectal tumorigenesis in familial adenomatous polyposis (FAP) results from somatic mutation of either the normal APC allele or another growth control gene in epithelial cells bearing a germline APC defect. The rate at which tumors develop is therefore dependent on the somatic mutation frequency; it is not known whether this is normal or elevated in FAP. We aimed to quantify stem cell somatic mutation in FAP, comparing it with hereditary nonpolyposis colorectal cancer (HNPCC) and Crohn's disease (CD). Stem cell somatic mutation frequency was studied in 47 FAP patients, 5 HNPCC patients, and 13 CD patients, all younger than 49 years, by quantifying crypt-restricted loss of O-acetyltransferase activity in sections of morphologically normal colonic mucosa from individuals heterozygous for this monogenically inherited polymorphism. Median stem cell somatic mutation frequency was significantly higher in FAP than HNPCC (4.2 x 10(-4) v 1.4 x 10(-4), Mann-Whitney U, P < .02). The level in CD (4.0 x 10(-4)) was similar to FAP. Mutated crypts occurred in groups more frequently in FAP (22%) than HNPCC (12%) or CD (10%), suggesting an increase in stem cell division associated with crypt fission in FAP. We conclude that stem cell somatic mutation frequency is raised in non-neoplastic colorectal mucosa in FAP. This is probably related to increased stem cell proliferation and contributes to the high rate of tumor formation in this condition.

Characterization in vitro and in vivo of the pig analogue of human CD59 using new monoclonal antibodies

CD59 is the sole characterized regulator of the complement membrane attack complex in humans. It is very widely and abundantly distributed, being present on all circulating cells, endothelia and epithelia, and in most tissues. CD59 analogues in rodents are distributed similarly. Interest in complement regulation in the pig has developed out of the current enthusiasm to exploit this species as a donor in xenotransplantation of organs to humans. We have recently isolated and cloned the pig analogue of human CD59. We here report the development and characterization of monoclonal antibodies against pig CD59. We have used these antibodies to develop efficient methods for the purification of pig CD59 to homogeneity from erythrocyte membranes and have obtained new information on the structure and function of the purified protein. The antibodies were found to function well in immunohistochemistry and have been used to perform a comprehensive survey of the expression and distribution of pig CD59 on cells and in organs of normal pigs. Pig CD59, like human CD59, is broadly expressed but there are some striking differences in tissue distribution, notably the apparent lack of pig CD59 on circulating platelets and on a subset of leucocytes in blood and lymphoid organs. The reported findings have important implications for the current approaches to avoiding complement-mediated hyperacute rejection in pig-to-human xenografts.

Granulomatous inflammation in sigmoid diverticulitis: two diseases or one?

AIMS

Histological appearances indistinguishable from Crohn's disease have been described in patients undergoing sigmoid colectomy for complicated diverticular disease. To investigate whether this finding represents coincidental dual pathology or merely a granulomatous colitis confined to the diverticular segment, we undertook clinical follow-up of affected patients.

METHODS AND RESULTS

Eight patients (median age 64 years, four males) whose sigmoid colectomy specimens showed acute diverticulitis and granulomatous inflammation were identified. All had a pre-operative diagnosis of diverticular disease and no previous evidence of Crohn's disease. Non-caseating epithelioid granulomas, unrelated to foreign material and usually unrelated to inflamed diverticular were present in the bowel wall of seven cases and in the regional lymph nodes of five. Three had granulomatous vasculitis and two had granulomas in 'background' mucosa. Mural lymphoid aggregates were identified in all cases. However, fissuring ulcers distinct from inflamed diverticula were not identified. On median follow-up of 51 months (range 18-112 months) none of the patients developed evidence of chronic inflammatory bowel disease. Three had died from unrelated causes.

CONCLUSIONS

Granulomatous inflammation appears to be part of a spectrum of sigmoid diverticulitis. In this setting, caution should be exercised to avoid an inappropriate diagnosis of Crohn's disease.

No difference in stem cell somatic mutation between the background mucosa of right- and left-sided sporadic colorectal carcinomas

Epidemiological, morphological, and molecular differences exist between carcinomas of the right and left sides of the large bowel. To investigate whether this is reflected in differences in somatic mutation frequency in the background mucosa, mutation of the neutral O-acetyltransferase gene (oat) was quantified in histologically normal resection margins from 20 informative (heterozygous) patients with caecal or ascending colon cancer (11 males, median age 75 years) and 20 with sigmoid colon or rectal cancer (10 males, median age 70 years). Mutant discordant crypts lacking O-acetyltransferase activity were visualized by mPAS staining and classified as wholly or partially involved by the mutant phenotype; median frequencies (x10(-4) were compared (Mann-Whitney U-test) after assessing a sample of more than 10,000 crypts per case. No significant difference was found between the frequencies of wholly involved mPAS-positive crypts in background mucosa of left- and right-sided cancers (p = 0.4569), indicating that tumours on both sides of the colon are associated with similar levels of lifetime-accumulated stem cell mutational load. However, partially involved mPAS-positive crypts were significantly more frequent in mucosa from left-sided cancers (p < 0.04), indicating increased mutational activity during the previous 12 months. Analysis of mucosa proximal and distal to left-sided cancers showed that this increase was due to a statistically higher frequency of partially involved crypts in proximal mucosa, which probably resulted from the obstructive effects of the tumour causing increased exposure of the proximal mucosa to luminal carcinogens and/or epithelial regeneration in response to low-grade inflammation or ischaemia. The findings indicate that although left-sided colonic cancer is commoner than right-sided cancer in the British population, carcinomas on both sides of the large bowel arise in a background of similar levels of stem cell mutational activity.

Clinical status of ulcerative colitis in patients who smoke

OBJECTIVES

Ulcerative colitis (UC) is largely a disease of nonsmokers. There are few patients who are current smokers, but we have identified a group and reviewed their clinical status, disease activity, and nicotine exposure to examine whether they remain well controlled while smoking.

METHODS

Fifty-one patients from three centers with verified UC were reviewed.

RESULTS

Thirty of the group were men; mean age 50 yr, with a mean age of onset of 37 yr. Twenty-two patients had proctosigmoid disease, 12 involvement of left colon, and 17 total colitis. All were current smokers; 41 were cigarette smokers averaging 17 daily. At the onset of colitis 30 were nonsmokers, 25 of them were ex-smokers and 19 developed colitis within 2 yr of stopping smoking. Twenty-eight believed smoking improved disease activity and none felt smoking had a detrimental effect on their UC. Eleven were receiving no medication for UC, 40 were receiving 5-ASA (5-aminosalicylic acid) preparations, and only two took oral steroids. All were in clinical remission, with the exception of one patient; mean St. Marks score was 1.5, out of a possible total of 22. Sigmoidoscopic grades were inactive in all patients except three. Histological assessment showed significant activity in only five. Median serum nicotine was 8 ng/ml (range, 0.4-24.4), median serum cotinine 180 ng/ml (range, 20-453), with corresponding salivary cotinine of 255 ng/ml (range, 34-683). Median rise in nicotine 2 min after a cigarette in 35 patients was 12.1 ng/ml (range, 0.4-44).

CONCLUSIONS

Because most current smokers with UC have inactive disease, smoking may contribute to the clinical remission in these patients.

Mice carrying a CD20 gene disruption

CD20 is a hallmark antigen of B lymphocytes. Its expression is restricted to precursor and mature B cells but it is not expressed on plasma cells. The protein is a membrane-embedded phosphoprotein that appears likely to transverse the membrane four times. Its function is unknown although CD20 has been variously proposed to play a role in B-cell activation, proliferation, and calcium transport. A unique homologue of human CD20 has been described in mouse, which also shows a B-cell-specific pattern of expression. Here we describe the generating of mice carrying a CD20 gene disruption. So far, we have failed to detect any major effect of the gene disruption on the differentiation and function of B lymphocytes as judged by the expression of surface markers, antigen receptor signaling, proliferative responses, or calcium uptake. We did note, however, that the mice homozygous for the gene disruption [generated by intercrossing (129 x C57BL/6)F1 CD20+/- heterozygotes] showed a substantial depletion of the sub-population of peritoneal B cells that lack expression of the B220 (RA3-6B2) isoform of CD45. The loss of the IgM+ 6B2- peritoneal B cells is not, however, attributable to the CD20 gene disruption itself. Rather, it segregates with a polymorphic difference between the 129 and C57BL/6 strains that is linked to the CD20 locus which, intriguingly, is itself close to the CD5 gene. This demonstrates that caution must be exercised when comparing the phenotypes of F2 litter-mates generated from crosses between 129 embryonic stem-cell-derived chimeras and mice of other strains.

A histopathological assessment of the response of rectal adenocarcinoma to combination chemo-radiotherapy: relationship to apoptotic activity, p53 and bcl-2 expression

AIMS

To investigate the use of pre-operative chemo-irradiation in downstaging advanced rectal cancer prior to surgical resection.

METHODS

We examined the pathological effects of chemo-irradiation on 24 rectal tumours and correlated the efficacy of treatment with the level of apoptosis, mitosis, P53 and bcl-2 protein expression on pre-treatment biopsies.

RESULTS

All tumours were resectable following chemo-irradiation. Six cancers showed complete regression with no viable tumour in the resection specimen. A significant correlation was found between spontaneous tumour apoptosis and tumour regression.

CONCLUSIONS

Our results suggest that in rectal cancer the apoptotic rate in untreated tumour tissue may predict sensitivity to radiation and cytotoxic agents. No relationship was found between regression and mitotic rate, p53 or bcl-2 expression.

Human islets of Langerhans express Fas ligand and undergo apoptosis in response to interleukin-1beta and Fas ligation

IDDM results from a progressive loss of pancreatic beta-cells that, in humans, may be triggered by a combination of genetic and environmental factors. Recently, attention has been focused on the hypothesis that the loss of beta-cells is initiated by inappropriate induction of apoptosis. We now demonstrate that human islets of Langerhans undergo apoptosis upon exposure to interleukin-1beta. The cytokine also sharply increases the number of cells that enter apoptosis on treatment with a stimulatory anti-Fas antibody. Western blotting and immunocytochemistry clearly show for the first time that human pancreatic beta-cells normally express Fas ligand. The results suggest that human islet cells are primed to undergo apoptosis by interleukin-1beta and that this involves the close association between cell-surface Fas and its ligand.

Clonal overexpression of metallothionein is induced by somatic mutation in morphologically normal colonic mucosa

Metallothionein (MT) overexpression occurs frequently in human tumours but the underlying mechanism is unknown. Morphologically normal-appearing mucosa from human colorectal carcinoma resection specimens and of the colons of ageing laboratory mice contains scattered single crypts whose cells show uniformly increased MT immunostaining, suggesting that MT overexpression arises directly from random crypt stem cell somatic mutation, followed by colonization of the clonal unit by the mutated progeny. This hypothesis has now been tested by quantifying the frequency of immunocytochemically detectable monocryptal colorectal MT overexpression, 5 and 30 days after injection of 8-week-old mice with a single dose of the mutagen dimethylhydrazine (DMH, 30 mg/kg subcutaneous). Otherwise normal-appearing MT-positive crypts were recorded as either wholly or partially involved by the overexpressing phenotype. Five days after DMH injection, the median frequency of partially involved MT-positive crypts was 11.7 x 10(-4), declining significantly to 1.8 x 10(-4) at 30 days (Mann-Whitney U, P < 0.01). In contrast, the median frequency of wholly involved crypts was 0.2 x 10(-4) at 5 days, increasing significantly (P < 0.005) to 12.9 x 10(-4) at 30 days. The frequency of MT-positive crypts and the time course of evolution of partially involved to wholly involved forms were similar to those described for mutation-induced crypt-restricted loss of glucose-6-phosphate dehydrogenase activity in mice treated with an identical DMH regimen. The findings indicate that cellular MT overexpression can occur as a direct consequence of somatic mutation, either cis-activating mutation(s) of the MT gene itself, or trans-activating mutation(s) of other genes involved in controlling MT expression. This is likely to be an important mechanism underlying MT overexpression in neoplasia. Such mutation-induced aberrant MT expression may be involved in the acquisition of selective cellular growth of survival advantage during tumour progression.

Multiple sequences from downstream of the J kappa cluster can combine to recruit somatic hypermutation to a heterologous, upstream mutation domain

Recruitment of somatic hypermutation to the Ig kappa locus has previously been shown to depend on the enhancer elements, Ei/MAR and E3'. Here we show that these elements are not sufficient to confer mutability. However, hypermutation is effectively targeted to a chimeric beta-globin/Ig kappa transgene whose 5' end is composed of the human beta-globin gene (promoter and first two exons) and whose 3' end consists of selected sequences derived from downstream of the J kappa cluster (Ei/MAR, C kappa + flank and E3'). Thus, multiple downstream Ig kappa sequences (all derived from 3' of the J kappa cluster) can combine to recruit mutation to a heterologous mutation domain. The location of this hypermutation domain is defined by the position of the transcription start site and this applies even if the Ig kappa Ei/MAR is positioned upstream of the promoter. Hotspots within the mutation domain are, however, defined by local DNA sequence as evidenced by a new hotspot being created within the beta-globin domain by a mutation within the transgene. We propose that multiple, moveable Ig kappa sequences (that are normally located downstream of the transcription start site) cooperate to bring a hypermutation priming factor to the transcription initiation complex; a mutation domain is thereby created downstream of the promoter but the local sequence defines the detailed pattern of mutation within that domain.

The anti-cancer drug etoposide can induce caspase-8 processing and apoptosis in the absence of CD95 receptor-ligand interaction

Caspase-8 (FLICE) can associate with and be activated by CD95 (APO-1/Fas), an apoptosis-inducing member of the Tumour Necrosis Factor receptor family. We find that, in Jurkat T cells, the DNA damaging anti-cancer drug etoposide induces apoptosis and, surprisingly, processing of caspase-8. Therefore, we have investigated whether etoposide involves CD95 receptor activation. We find that etoposide does not induce CD95 ligand expression at the mRNA level. In addition, blocking of CD95 receptor function with a specific antibody does not inhibit etoposide-induced apoptosis. Apparently, in Jurkat cells, etoposide can induce caspase-8 processing and apoptosis in a CD95-independent fashion. Likewise, we find that thymocytes from the CD95-deficient lpr/lpr mouse strain readily undergo apoptosis in response to etoposide. Moreover, since inhibition of the secretory pathway with brefeldin A does not inhibit etoposide-induced apoptosis, we exclude the requirement for a newly synthesized receptor ligand to induce the apoptotic pathway. We conclude that, at least in certain cell types, etoposide does not require CD95 receptor function to induce caspase-8 processing and apoptosis.

Nicotine enemas for active ulcerative colitis--a pilot study

BACKGROUND

Since transdermal nicotine is of value in the treatment of active ulcerative colitis but is often associated with side-effects, an alternative in the form of topical therapy with nicotine enemas has been developed.

METHODS

In an open study, 22 patients with active colitis, all non-smokers, were asked to take a 100 mL enema containing 6 mg of nicotine every night for 4 weeks. Pre-trial treatment using mesalazine (n = 16), oral prednisolone (8), cyclosporin (1) and azathioprine (1) was kept constant for the month prior to assessment and during the study period. Symptoms, with stool frequency, were recorded on a diary card and an endoscopy was performed with rectal biopsy at the beginning of the study and after 4 weeks.

RESULTS

Seventeen of the 22 patients completed 1 month of treatment. Mean duration of relapse was 29 weeks, range 3-94. Sixteen of 17 improved their St Mark's score. Urgency and stool frequency improved in 12 patients, sigmoidoscopic and histological scores in 10. Three patients had a full remission of symptoms with normal sigmoidoscopy. Six of 10 with a partial response continued with the enemas for a second month and five showed further improvement with full remission in two. The enema appeared effective when added to conventional treatment and produced few side-effects.

CONCLUSION

Topical nicotine therapy for ulcerative colitis may have a place in future management, but controlled studies are needed.

Viral promoter expression in CEM-C7 and Jurkat human T-lymphoid cell lines

The strength of various viral promoters was examined in human T lymphoblastoid cell lines. CMV, RSV and SV40 promoter based-luciferase constructs were transiently transfected into CEM-C7 and Jurkat cells in order to compare promoter strength in each cell type. It was found that the CMV promoter was 10-fold stronger than the RSV promoter in Jurkat cells, but equivalent to the RSV promoter in CEM-C7 cells. Both the CMV and RSV promoters were significantly stronger than the SV40 promoter in Jurkat and CEM-C7 cells. In summary, promoter strengths are cell line specific (Jurkat: CMV > RSV >> SV40; CEM-C7: RSV = CMV >> SV40) and care must be exercised in choosing promoters intended to provide overexpression of chimeric genes.

Cells strongly expressing Ig(kappa) transgenes show clonal recruitment of hypermutation: a role for both MAR and the enhancers

The V regions of immunoglobulin kappa transgenes are targets for hypermutation in germinal centre B cells. We show by use of modified transgenes that the recruitment of hypermutation is substantially impaired by deletion of the nuclear matrix attachment region (MAR) which flanks the intron-enhancer (Ei). Decreased mutation is also obtained if Ei, the core region of the kappa3'-enhancer (E3') or the E3'-flank are removed individually. A broad correlation between expression and mutation is indicated not only by the fact that the deletions affecting mutation also give reduced transgene expression, but especially by the finding that, within a single mouse, transgene mutation was considerably reduced in germinal centre B cells that poorly expressed the transgene as compared with strongly expressing cells. We also observed that the diminished mutation in transgenes carrying regulatory element deletions was manifested by an increased proportion of B cells in which the transgene had not been targeted at all for mutation rather than in the extent of mutation accumulation once targeted. Since mutations appear to be incorporated stepwise, the results point to a connection between transcription initiation and the clonal recruitment of hypermutation, with hypermutation being more fastidious than transcription in requiring the presence of a full complement of regulatory elements.

Caspase activity is required for commitment to Fas-mediated apoptosis

Recognition of the widespread importance of apoptosis has been one of the most significant changes in the biomedical sciences in the past decade. The molecular processes controlling and executing cell death through apoptosis are, however, still poorly understood. The ICE (Interleukin-1beta Converting Enzyme) family-recently named the caspases for cysteine aspartate-specific proteases-plays a central role in apoptosis and may well constitute part of the conserved core mechanism of the process. Potentially, these proteases may be of great significance, both in the pathology associated with failure of apoptosis and also as targets for therapeutic intervention where apoptosis occurs inappropriately, e.g. in degenerative disease and AIDS. However, this is only likely if caspase activity is required before commitment to mammalian cell death. Here, we have used both peptide inhibitors and crmA transfection to inhibit these proteases in intact cells. Our experiments show that selective inhibition of some caspases protects human T cells (Jurkat and CEM-C7) from Fas-induced apoptosis, dramatically increasing their survival (up to 320-fold) in a colony-forming assay. This suggests that dysfunction of some, but not all, caspases could indeed play a crucial part in the development of some cancers and autoimmune disease, and also that these proteases could be appropriate molecular targets for preventing apoptosis in degenerative disease.

Acceleration of intracellular targeting of antigen by the B-cell antigen receptor: importance depends on the nature of the antigen-antibody interaction

The B-cell antigen receptor (BCR) internalizes bound antigen such that antigen-derived peptides become associated with emigrating major histocompatibility complex (MHC) class II molecules for presentation to T cells. Experiments with B-cell transfectants reveal that BCR confers a specificity of intracellular targeting since chimeric antigen receptors which internalize antigen by virtue of a heterologous cytoplasmic domain do not necessarily give rise to presentation. In contrast, however, previous studies have shown that antigen binding to irrelevant cell surface molecules (e.g. transferrin receptor, MHC class I) can ultimately lead to presentation. The solution to this paradox appears to be that the intracellular targeting by BCR actually reflects an acceleration of antigen delivery. Depending on the nature of the BCR-antigen interaction, this accelerated targeting can be essential in determining whether or not internalization leads to significant presentation. Physiologically, the accelerated delivery of antigen by BCR could prove of particular importance early in the immune response when antigen-BCR interaction is likely to be poor.

Guidelines for the initial biopsy diagnosis of suspected chronic idiopathic inflammatory bowel disease. The British Society of Gastroenterology Initiative

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Colorectal cancer pathology reporting: a regional audit

AIMS

To audit the information content of pathology reports of colorectal cancer specimens in one National Health Service region.

METHODS

All reports of colorectal cancer resection specimens from the 17 NHS histopathology laboratories in Wales during 1993 were evaluated against: (a) standards previously agreed as desirable by pathologists in Wales; and (b) standards considered to be the minimum required for informed patient management.

RESULTS

1242 reports were audited. There was notable variation in the performance of different laboratories and in the completeness of reporting of individual items of information. While many items were generally well reported, only 51.5% (640/ 1242) of rectal cancer reports contained a statement on the completeness of excision at the circumferential resection margin and only 30% (373/1242) of all reports stated the number of involved lymph nodes. All of the previously agreed items were contained in only 11.3% (140/1242) of reports on colonic tumours and 4.0% (40/1242) of reports on rectal tumours. Seventy eight per cent (969/1242) of colonic carcinoma reports and 46.6% (579/ 1242) of rectal carcinoma reports met the minimum standards.

CONCLUSIONS

The informational content of many routine pathology reports on colorectal cancer resection specimens is inadequate for quality patient management, for ensuring a clinically effective cancer service through audit, and for cancer registration. Template proforma reporting using nationally agreed standards is recommended as a remedy for this, along with improved education, review of laboratory practices in the light of current knowledge, and further motivation of pathologists through their involvement in multidisciplinary cancer management teams.