Coexposure to mercury increases immunotoxicity of trichloroethylene

We have shown previously that chronic (32 weeks) exposure to occupationally relevant concentrations of the environmental pollutant trichloroethylene (TCE) induced autoimmune hepatitis (AIH) in autoimmune-prone MRL+/+ mice. In real-life, individuals are never exposed to only one chemical such as TCE. However, very little is known about the effects of chemical mixtures on the immune system. The current study examined whether coexposure to another known immunotoxicant, mercuric chloride (HgCl(2)), altered TCE-induced AIH. Female MRL+/+ mice were treated for only 8 weeks with TCE (9.9 or 186.9 mg/kg/day in drinking water) and/or HgCl(2) (260 μg/kg/day, sc). Unlike mice exposed to either TCE or HgCl(2) alone, mice exposed to both toxicants for 8 weeks developed significant liver pathology commensurate with early stages of AIH. Disease development in the coexposed mice was accompanied by a unique pattern of anti-liver and anti-brain antibodies that recognized, among others, a protein of approximately 90 kDa. Subsequent immunoblotting showed that sera from the coexposed mice contained antibodies specific for heat shock proteins, a chaperone protein targeted by antibodies in patients with AIH. Thus, although TCE can promote autoimmune disease following chronic exposure, a shorter exposure to a binary mixture of TCE and HgCl(2) accelerated disease development. Coexposure to TCE and HgCl(2) also generated a unique liver-specific antibody response not found in mice exposed to a single toxicant. This finding stresses the importance of including mixtures in assessments of chemical immunotoxicity.

Experience with Use of the Oncotype DX Gene Assay Test in a Multicenter Community-Based Healthcare System

Background:Oncotype DX has been validated to quantify the risk of distant recurrence and predict the benefit of chemotherapy (CT) in ER positive, node negative breast cancer treated with tamoxifen. A retrospective study was undertaken to assess the use of the Oncotype DX test at Intermountain Healthcare. Intermountain is a not-for-profit healthcare system with 21 inpatient facilities, 9 comprehensive cancer centers and 42 affiliated medical oncologists ranging from single practitioners to multiphysician groups.Methods: This study contains a group of T1-3 N0 ER+ breast cancer patients who received an Oncotype DX test paired with a control group of non-tested T1-T3 N0 ER+ patients receiving hormone therapy (HT) from the same period. Data comes from a supplemental database containing treatment and follow-up data from individual physician offices combined with data from Intermountain's cancer registry. To ensure data completeness, Genomic Health provided a list of relevant Oncotype DX results for study patients. The analysis was done using multivariate logistic regression and controlled for age, tumor size, grade and T stage.Results: From 2005 to 2008, Oncotype DX testing was performed on tumor specimens from 285 patients. 8 patients had positive nodes and 4 patients were ER negative. In addition, 9 patients did not and will not receive HT (5 refused, 4 contraindicated) and 9 patients have yet to begin HT. 11 patients were lost to follow-up. Of the remaining 244 patients who form the study group, six patients were Her-2 neu positive (1 high recurrence score (RS), 3 intermediate and 2 low). Tumor size ranged from <1 cm to 7 cm, but 80% were <2 cm. 120 study patients (49%) had a low RS, 95 (39%) intermediate and 29 (12%) high. Only 2% of patients in the low RS group received CT, whereas 93% of patients in the high RS group and 40% in the intermediate RS group received CT.An analysis of potential factors affecting CT treatment decision making in the intermediate RS group showed that 60% of the 15 patients under age 50 received CT, compared to 36% of the 80 patients age 50 and over. CT was given in 35% of grade 1, 40% of grade 2 and 50% of grade 3 tumors. 43% of patients with a <1 cm tumor received CT compared to 42% of 1-2 cm tumors and 28% of tumors >2 cm. Compared to our control group of 688 patients, Oncotype DX-tested patients are younger (p<0.01), less likely to have T1a (p=0.03), more likely to have T1c (p<0.01) or T2 (p=0.03) tumors and less likely to undergo CT (p<0.01). Low RS patients are less likely to receive CT (p<0.01) and high RS patients more likely to receive CT (p<0.01), whereas intermediate RS patients showed no significant difference (p=0.07) but were trending toward receiving less CT than the control group.Conclusions:Virtually all patients with a low RS received only HT, while most patients with a high RS also received CT. In patients with an intermediate RS, younger age and higher grade may impact clinicians' decisions to administer CT, while a larger tumor size does not. Overall, patients undergoing Oncotype DX testing are less likely to receive CT. These data indicate that the use of Oncotype DX testing facilitated appropriate therapeutic decisions in most patients.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6058.

Impact of Recording of Pre-Analytical Specimen Handling Conditions for ER and PR Testing in Women with Breast Cancer

Background: Hormone receptor testing is important in the management of women with breast cancer. We previously reported potential adverse effects of variable specimen and prolonged specimen handling conditions on ER (estrogen receptor) test results (2005 SABCS, abstract#5107).Objective: To compare prevalence of ER and PR (progesterone receptor) negative test results following standardization of pre-analytical specimen handling conditions at Intermountain facilities.Methods: Prospective, quasi-experimental study design of 6 Intermountain facilities. Facilities were separated into 2 categories: experimental (2 facilities) and control (4 facilities) groups. Pre-analytical specimen handling conditions (including recording of time to fixative and duration of fixation in neutral buffered formalin) were standardized at experimental facilities but not at control facilities. Standardization consisted of educating operating and grossing room staff about appropriate specimen handling and the value of recording time to fixation and fixative duration as a way to improve pre-analytic standardization. OR staff was called in any cases where times were not recorded. Study population includes women undergoing breast cancer surgery and who were tested for ER/PR status between January 2008 and January 2009. Specimen handling conditions and ER/PR test results were collected manually. Covariates were retrieved from cancer registry and included age, grade, positive lymph nodes, specimen type, and tumor stage. Multivariate logistic regression was used to compare prevalence of ER and PR negativity between experimental and control facilities after controlling for covariates.Results: 1054 women with breast cancer were tested for ER/PR status during the study period. The average age was 60.2 years (59.2 years for control cases and 61.1 years for the experimental group). The overall prevalence of ER and PR negative tests was respectively 18.5% and 27.3%. Average time to fixative at experimental facilities was 18.4 minutes (SE=3.1; 95% CI, 12.2-25.6) and average time in fixative was 18.0 hours (SE=0.4; 95% CI, 17.2-18.8). Compared to experimental facilities, both the prevalence of ER and PR negativity was higher (16.9% vs 19.7%) and (23.9% vs 30.0%) at control facilities. After controlling for covariates there was no difference in prevalence of ER negativity (p=0.13) between the two groups. However, the prevalence of PR negativity remains significantly higher (p<0.01) at control facilities compared to experimental facilities even after controlling for covariates.Conclusions: The prevalence of ER and PR negative results was lower following staff education and recording of pre-analytical specimen handling conditions. Our data suggest that staff education and recording of pre-analytical specimen handling conditions has the potential to optimize hormone receptor test results. It also shows the feasibility of fixing tissue routinely after less than an hour interval between time of breast cancer tissue removal and fixation and underscores the value of standardization of pre-analytic handling as a method to improve ER and PR testing on breast cancer specimens.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4154.

Mechanisms of heavy metal-induced autoimmunity

Chemical exposure can trigger or accelerate the development of autoimmune manifestations. Although heavy metals are elementary chemical structures, they can have profound and complex effects on the immune system. In genetically susceptible mice or rats, administration of subtoxic doses of mercury induces both the production of highly specific autoantibodies and a polyclonal activation of the immune system. We review in this article some of the mechanisms by which heavy metal exposure can lead to autoimmunity.

A novel assay for discovery and characterization of pro-apoptotic drugs and for monitoring apoptosis in patient sera

We have developed an apoptosis assay based on measurement of a neoepitope of cytokeratin-18 (CK18-Asp396) exposed after caspase-cleavage and detected by the monoclonal antibody M30. The total amount of caspase-cleaved CK18 which has accumulated in cells and tissue culture media during apoptosis is measured by ELISA. The sensitivity is sufficient for use in the 96-well format to allow high-through-put screening of drug libraries. We here describe strategies allowing classification of pro-apoptotic compounds according to their profiles of induction of apoptosis in the presence of pharmacological inhibitors. The time course of induction of CK18 cleavage can furthermore be used to distinguish structurally similar compounds. We propose that compounds that induce rapid CK18 cleavage have mechanisms of actions distinct from conventional genotoxic and microtubuli-targeting agents, and we present one example of an agent that induces almost immediate mitochondrial depolarization and cytochrome c release. Finally, CK18-Asp396 cleavage products are released from cells in tissue culture, and presumably from tumor cells in vivo. These products can be measured in sera from cancer patients. We present evidence suggesting that it will be possible to use the M30-ELISA assay for measuring chemotherapy-induced apoptosis in patient sera, opening possibilities for monitoring therapy.

Disruption of epithelial gamma delta T cell repertoires by mutation of the Syk tyrosine kinase

Chimeric mice in which lymphocytes are deficient in the Syk tyrosine kinase have been created. Compared with Syk-positive controls, mice with Syk -/- lymphocytes display substantial depletion of intraepithelial gamma delta T cells in the skin and gut, with developmental arrest occurring after antigen receptor gene rearrangement. In this dependence on Syk, subsets of intraepithelial gamma delta T cells are similar to B cells, but distinct from splenic gamma delta T cells that develop and expand in Syk-deficient mice. The characteristic associations of certain T-cell receptor V gamma/V delta gene rearrangements with specific epithelia are also disrupted by Syk deficiency.

Syk tyrosine kinase required for mouse viability and B-cell development

The Syk cytoplasmic protein-tyrosine kinase has two amino-terminal SH2 domains and a carboxy-terminal catalytic domain. Syk, and its close relative ZAP-70, are apparently pivotal in coupling antigen- and Fc-receptors to downstream signalling events. Syk associates with activated Fc receptors, the T cell receptor complex and the B-cell antigen-receptor complex (BCR) in immature and mature B lymphocytes. On receptor activation, the tandem SH2 domains of Syk bind dual phosphotyrosine sites in the conserved ITAM motifs of receptor signalling chains, such as the immunoglobulin alpha and beta-chains of the BCR, leading to Syk activation. Here we have investigated Syk function in vivo by generating a mouse strain with a targeted mutation in the syk gene. Homozygous syk mutants suffered severe haemorrhaging as embryos and died perinatally, indicating that Syk has a critical role in maintaining vascular integrity or in wound healing during embryogenesis. Analysis of syk-/- lymphoid cells showed that the syk mutation impaired the differentiation of B-lineage cells, apparently by disrupting signalling from the pre-BCR complex and thereby preventing the clonal expansion, and further maturation, of pre-B cells.

Murine pregnancy decidua produces a unique immunosuppressive molecule related to transforming growth factor beta-2

Non-T small lymphocytic suppressor cells in murine allopregnancy release a potent immunosuppressive factor in vitro that is neutralized by rabbit anti-transforming growth factor (TGF)-beta. Previous studies have suggested that the decidual suppressor factor (DSF) is smaller than TGF-beta 1, and in this paper, we show that DSF on HPLC-sieving columns also elutes later than TGF-beta 2. Nevertheless, DSF has the ability to promote anchorage-independent growth of NRK fibroblasts similar to TGF-beta s. Using turkey antibodies specific for TGF-beta 1 or beta 2, we show that DSF is related to TGF-beta 2 rather than TGF-beta 1, and this relationship was confirmed by using a panel of murine mAb to TGF-subtypes. PAGE and Western blotting showed that the TGF-beta 2-reactive molecules in HPLC-purified DSF was slightly smaller than TGF-beta 2 and approximately 20 to 23 kDa. The DSF molecule is therefore closely related to TGF-beta 2 but as released from decidua, differs in size. The TGF-beta 2-related decidual suppressor factor was also obtained from the decidua of synpregnant C.B.-17 severe combined immune deficiency (SCID) and pregnant SCID-BG (C57BL/6 background) mice, confirming the lack of T or B cell dependence of DSF production and the generality of production of a TGF-beta-related suppressor factor by decidua associated with successful pregnancy in mice.

Murine pregnancy decidua produces a unique immunosuppressive molecule related to transforming growth factor beta-2

Non-T small lymphocytic suppressor cells in murine allopregnancy release a potent immunosuppressive factor in vitro that is neutralized by rabbit anti-transforming growth factor (TGF)-beta. Previous studies have suggested that the decidual suppressor factor (DSF) is smaller than TGF-beta 1, and in this paper, we show that DSF on HPLC-sieving columns also elutes later than TGF-beta 2. Nevertheless, DSF has the ability to promote anchorage-independent growth of NRK fibroblasts similar to TGF-beta s. Using turkey antibodies specific for TGF-beta 1 or beta 2, we show that DSF is related to TGF-beta 2 rather than TGF-beta 1, and this relationship was confirmed by using a panel of murine mAb to TGF-subtypes. PAGE and Western blotting showed that the TGF-beta 2-reactive molecules in HPLC-purified DSF was slightly smaller than TGF-beta 2 and approximately 20 to 23 kDa. The DSF molecule is therefore closely related to TGF-beta 2 but as released from decidua, differs in size. The TGF-beta 2-related decidual suppressor factor was also obtained from the decidua of synpregnant C.B.-17 severe combined immune deficiency (SCID) and pregnant SCID-BG (C57BL/6 background) mice, confirming the lack of T or B cell dependence of DSF production and the generality of production of a TGF-beta-related suppressor factor by decidua associated with successful pregnancy in mice.

Release of ferrous iron from ferritin by liver microsomes: a possible role in the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin

Nonheme iron is synergistic with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in producing hepatotoxicity in mice. Fe2+ rather than Fe3+ is the probable toxin and we speculated that TCDD, an inducer of microsomal electron transport, might favour reduction of iron. We have defined a system which will release Fe2+ from ferritin (Fe3+) under anaerobic conditions and in the presence of added flavin mononucleotide (FMN). The rate of reduction iron was proportional (a) to microsomal protein from 0.5 to greater than 3 mg/mL, (b) to the activity of NADPH-cytochrome c reductase over 0.1 U/mL, (c) to ferritin at concentrations exceeding iron concentrations greater than 200 mumol/L, and (d) to the concentration of FMN when it was less than 125 mumol/L. The system was approximately twice as active with NADPH as with NADH as electron donor. The linear phase of iron release did not commence immediately, but followed a delay (+/- 0.5 min) after adding FMN to an anaerobic mixture containing microsomes, ferritin, an NADPH-generating system, and an oxygen-scavenging system. When microsomes from untreated, phenobarbital-treated (3 days), or TCDD-treated (1 or 3 weeks) rats were compared, iron release correlated most closely with the cytochrome P-450 concentration. However, when the microsomal proteins were solubilized and the NADPH-cytochrome c reductase and cytochrome P-450 activities were separated, reduction of ferritin iron was shown to be a function only of the reductase fraction, except that the delay in initiating release of Fe2+ was increased with purified reductase and decreased when a monooxygenase system was reconstituted with cytochrome (phenobarbital or TCDD induced) and lipid.(ABSTRACT TRUNCATED AT 250 WORDS)