Anti-CD3-induced T-cell activation in vivo--I. Flow cytometric analysis of dose-responsive, time-dependent, and cyclosporin A-sensitive parameters of CD4+ and CD8+ cells from the draining lymph nodes of C57Bl/6 mice

Effector and Activated T Cells Induce Preterm Labor and Birth That Is Prevented by Treatment with Progesterone

Preterm labor commonly precedes preterm birth, the leading cause of perinatal morbidity and mortality worldwide. Most research has focused on establishing a causal link between innate immune activation and pathological inflammation leading to preterm labor and birth. However, the role of maternal effector/activated T cells in the pathogenesis of preterm labor/birth is poorly understood. In this study, we first demonstrated that effector memory and activated maternal T cells expressing granzyme B and perforin are enriched at the maternal-fetal interface (decidua) of women with spontaneous preterm labor. Next, using a murine model, we reported that prior to inducing preterm birth, in vivo T cell activation caused maternal hypothermia, bradycardia, systemic inflammation, cervical dilation, intra-amniotic inflammation, and fetal growth restriction, all of which are clinical signs associated with preterm labor. In vivo T cell activation also induced B cell cytokine responses, a proinflammatory macrophage polarization, and other inflammatory responses at the maternal-fetal interface and myometrium in the absence of an increased influx of neutrophils. Finally, we showed that treatment with progesterone can serve as a strategy to prevent preterm labor/birth and adverse neonatal outcomes by attenuating the proinflammatory responses at the maternal-fetal interface and cervix induced by T cell activation. Collectively, these findings provide mechanistic evidence showing that effector and activated T cells cause pathological inflammation at the maternal-fetal interface, in the mother, and in the fetus, inducing preterm labor and birth and adverse neonatal outcomes. Such adverse effects can be prevented by treatment with progesterone, a clinically approved strategy.

Chromosome Segregation Fidelity in Epithelia Requires Tissue Architecture

Much of our understanding of chromosome segregation is based on cell culture systems. Here, we examine the importance of the tissue environment for chromosome segregation by comparing chromosome segregation fidelity across several primary cell types in native and nonnative contexts. We discover that epithelial cells have increased chromosome missegregation outside of their native tissues. Using organoid culture systems, we show that tissue architecture, specifically integrin function, is required for accurate chromosome segregation. We find that tissue architecture enhances the correction of merotelic microtubule-kinetochore attachments, and this is especially important for maintaining chromosome stability in the polyploid liver. We propose that disruption of tissue architecture could underlie the widespread chromosome instability across epithelial cancers. Moreover, our findings highlight the extent to which extracellular context can influence intrinsic cellular processes and the limitations of cell culture systems for studying cells that naturally function within a tissue.

Discovery of a Potent, Orally Bioavailable PI4KIIIβ Inhibitor (UCB9608) Able To Significantly Prolong Allogeneic Organ Engraftment in Vivo

The primary target of a novel series of immunosuppressive 7-piperazin-1-ylthiazolo[5,4- d]pyrimidin-5-amines was identified as the lipid kinase, PI4KIIIβ. Evaluation of the series highlighted their poor solubility and unwanted off-target activities. A medicinal chemistry strategy was put in place to optimize physicochemical properties within the series, while maintaining potency and improving selectivity over other lipid kinases. Compound 22 was initially identified and profiled in vivo, before further modifications led to the discovery of 44 (UCB9608), a vastly more soluble, selective compound with improved metabolic stability and excellent pharmacokinetic profile. A co-crystal structure of 44 with PI4KIIIβ was solved, confirming the binding mode of this class of inhibitor. The much-improved in vivo profile of 44 positions it as an ideal tool compound to further establish the link between PI4KIIIβ inhibition and prolonged allogeneic organ engraftment, and suppression of immune responses in vivo.

Enhanced activation-induced cell death as a mechanism of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced immunotoxicity in peripheral T cells

T cells upon activation undergo apoptosis, a process termed activation-induced cell death (AICD). In the current study, we investigated whether 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) increases AICD and whether this constitutes one of the mechanisms by which TCDD induces immunotoxicity. To this end, C57BL/6+/+, C57BL/6 gld/gld (Fas ligand-defective) and C57BL/6 lpr/lpr (Fas-deficient) mice were injected with TCDD (50 microg/kg body weight, ip) or the vehicle (corn oil) and with anti-CD3 mAbs into the footpads. 3 days later, inguinal and popliteal lymph node cells were harvested, pooled and enumerated. Cells were cultured in vitro with anti-CD3 mAbs and cell proliferation was measured. Also, such cells were studied for their ability to undergo apoptosis upon in vitro culture with either tissue culture medium alone or with anti-CD3 mAbs. The data demonstrated that lymph nodes from TCDD-treated wild-type (+/+) mice showed a decrease in cellularity and the T cells exhibited decreased responsiveness to anti-CD3 mAbs when compared to the vehicle-treated control group. Furthermore, such cells from TCDD-treated mice exhibited increased levels of apoptosis upon in vitro culture when compared to the cells from vehicle-treated mice. In contrast, activated lymph nodes from TCDD-treated C57BL/6 gld/gld and C57BL/6 lpr/lpr mice showed normal cellularity and T cell responsiveness to anti-CD3 stimulation when compared to the vehicle controls. In addition, the activated lymph node T cells from the TCDD-treated C57BL/6 gld/gld and C57BL/6 lpr/lpr mice failed to exhibit increased apoptosis when compared to the controls. The current study demonstrates that the immunotoxic effects of TCDD in activated peripheral T cells may result from increased AICD mediated through Fas-Fas ligand interactions.

Effect of a single or repeated dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on T cell subpopulations in the Long-Evans rat

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) exposure results in adverse effects on the immune system of experimental animals. The purpose of this study was to compare the effects of a single and repeated dosing of TCDD on splenic T-cell subpopulations in Long Evans rats 9 days post-exposure to TCDD. A single dose (25 microg/kg body weight) of TCDD resulted in reduced body weight. The percentage and total number of CD4+ or CD8+ subsets and percentage of CD4+ or CD8+ cell cycling in the S and G2M phases were similar in the single dosed (25 microg/kg body weight) TCDD group compared with the vehicle control. A repeated dose (5 microg/kg/day for 5 days) of TCDD also resulted in a significant reduction in body weight. However, multiple doses of TCDD significantly decreased the percentage of the CD4+ subset and the percentage of CD4+ cells cycling in the S and G2M phases. No significant change occurred in the CD8+ cell subpopulation after single or multiple dosing with TCDD. These results demonstrated that repeated dosing of TCDD decreased the total percentage of CD4+ cells and the percentage of CD4+ cells cycling 9 days post-exposure, while an analogous single dose of TCDD failed to affect the CD4+ cell subpopulation. The difference in biological responses to a single versus 'equivalent' multiple (cumulative) dose of TCDD is discussed.

Selective modulation of B-cell activation markers CD86 and I-Ak on murine draining lymph node cells following allergen or irritant treatment

It is well known that T cells are key effector cells in the development of allergic contact dermatitis. However, we and others have shown that mice exposed to contact allergens show a preferential increase in B lymphocytes in the draining lymph nodes (DLN) as seen by an increase in the percentage of B220+ or IgG/IgM+ cells. The purpose of the present investigation was to determine whether chemical allergens, in contrast to irritants, would modulate B-cell activation markers, CD86 and I-Ak, on B cells isolated from DLN of treated mice using the local lymph node assay (LLNA) protocol. Mice were treated on the ears for 3 consecutive days with concentrations of allergens (1-chloro-2,4-dinitrobenzene, alpha-hexylcinnamaldehyde, 4-ethoxymethylene-2-phenyl-2-oxazoline-5-one, and trinitrochlorobenzene), or irritants (benzalkonium chloride and sodium lauryl sulfate), which caused an increase in the number of DLN cells. The DLN were excised 72 h following the final chemical treatment, and the cells were prepared for analysis by flow cytometry. In mice treated with allergens an increase in the median intensity of I-AK and CD86 on B220+ or IgG/IgM+ B cells was observed compared to mice treated with irritants or vehicles. Mice treated with allergens demonstrated an increase in the median intensity of CD86 on B220+ B cells that was dose dependent and peaked at 72 h following the final allergen treatment. The increase in the median intensity of I-AK also was dose dependent but peaked at 96 h. Finally, T and B cells isolated from both allergen- and irritant-treated mice demonstrated an increase in [3H]thymidine incorporation compared to vehicle-treated and naïve mice at 72 h following the final chemical treatment. The results suggest that B cells isolated from DLN of allergen-treated mice are activated and proliferating. Analysis of B-cell activation markers may be useful in differentiating allergen and irritant responses in the draining lymph nodes of chemically treated mice.

Local lymph node assay: differentiating allergic and irritant responses using flow cytometry

The murine local lymph node assay (LLNA) is a method for assessing the contact sensitization potential of chemicals. Based on events that occur during the induction phase of a contact sensitization response, the LLNA measures the in vivo proliferation of cells in the draining lymph nodes (DLNs) of mice following topical exposure to chemicals. In terms of predictive identification of important skin sensitizers, the LLNA has been shown to be at least as sensitive as, and much more reliable than, current guinea pig tests. However, proliferation has also been observed following treatment with some irritants. In an attempt to distinguish allergic from irritant-induced proliferation, flow cytometric techniques have been used to examine the phenotype of lymphocyte subsets in the DLNs as well as markers of T-lymphocyte activation and memory. Mice were treated on the ears for 3 consecutive days with allergens or irritants. The DLNs were harvested 72 h after the final treatment. Single-cell suspensions were prepared, counted, and stained for analysis of the percentages of T cells and B cells and T-cell expression of two adhesion molecules that have been associated with differentiating naïve and activated/memory T cells, CD62L (L-selectin) and CD44 (H-cam). Increases in lymph node cellularity were observed in both allergen- and irritant-treated mice relative to naïve and vehicle-treated animals. Mice treated with allergens showed a preferential increase in the percentage of B220(+) B cells compared with irritant-treated mice. Treatment with allergens, but not irritants, resulted in a selective increase in the percentages of CD4(+) and CD8(+) cells expressing the T-cell activation/memory phenotype CD62L(lo)CD44(hi). Taken together, flow cytometric analysis of cell phenotype and expression of T-cell activation/memory markers may provide important information for differentiating allergen- and irritant-induced proliferative responses in the DLNs of chemically treated mice.

Effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin on anti-CD3-induced changes in T-cell subsets and cytokine production

The influence of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure on the cytokine-dependent toxicity syndrome induced by the injection of 145-2C11 (anti-CD3), a hamster monoclonal antibody to the CD3 epsilon portion of the murine T-cell receptor, was studied. This syndrome has been attributed to the transient release of several cytokines including TNF-alpha, IFN-gamma, IL-2, IL-3, IL-6, and GM-CSF. Exposure of C57Bl/6 mice to TCDD (15 micrograms/kg) 2 days prior to anti-CD3 injection exacerbated anti-CD3-induced toxicity as evidenced by significantly enhanced and prolonged body weight loss and lymphoid tissue atrophy. Unexpectedly, TCDD exposure did not alter plasma levels of TNF or IL-2 at any time after anti-CD3 injection. However, plasma IFN-gamma was significantly reduced at 24 h and plasma IL-6 levels were elevated 48 h after anti-CD3 injection in TCDD-treated mice. In addition, TCDD exposure resulted in elevated levels of plasma GM-CSF at 24 and 48 h. Since the body weight of TCDD-treated mice diverged from vehicle-treated mice at 48 h, it suggests that the increased IL-6 and GM-CSF may have contributed to the prolonged loss of body weight. The ability of spleen cells from vehicle- and TCDD-treated mice to produce cytokines was evaluated in vitro at various times after anti-CD3 injection. TCDD treatment resulted in reduced IL-2 and GM-CSF production at 90 min but increased GM-CSF production at 48 h post-anti-CD3 injection. In contrast, TCDD exposure did not influence cytokine production by spleen cells from mice injected with a control IgG and activated in vitro with anti-CD3. Flow cytometric analysis showed that the percentage of CD4+ cells in the draining lymph nodes from TCDD-treated mice was reduced 48-144 h post-anti-CD3 injection. In contrast, the percentage of CD8+ cells was not affected by TCDD exposure. A high fraction of lymph node cells (LNC) from TCDD-treated animals showed decreased forward angle light scatter and increased 90 degrees light scatter following anti-CD3 injection, which is a pattern characteristic of cells undergoing apoptosis. In contrast, few LNC from vehicle-treated animals showed this light scatter profile. These data suggest that TCDD may be targeting T-helper cells during activation resulting in activation-driven cell death (apoptosis) rather than differentiation.

Immunopharmacological profile of SR 31747: in vitro and in vivo studies on humoral and cellular responses

In our preceding paper, we demonstrated that both human and rat lymphocytes possess saturable high-affinity binding sites for the new sigma ligand SR 31747. Here we investigate the potential activity of this ligand on immune responses. In vitro, our study shows that SR 31747 exerts a concentration- and time-dependent inhibition of proliferative response to mitogens on mouse and human lymphocytes without affecting cell viability. This suppressive effect elicited by SR 31747 occurs over a concentration range which correlates with the pharmacological profile of the molecule in binding assays, strongly suggesting that SR 31747 acts through a receptor-mediated process. We showed that the SR 31747 effect, which was observed on purified T lymphocytes, affects a late event in the activation process which occurs after the G1 during the S phase of the cell cycle. Interestingly, no anti-proliferative effect was observed in a variety of tumor cell lines, supporting a specific effect limited to normal immune cells. In vivo, in mice, treatment with SR 31747 prevented both graft-versus-host disease and delayed-type hypersensitivity granuloma formation, while antibody response to sheep red blood cells was not affected. These results strongly suggest that the sigma-related receptor recognized by SR 31747 is very likely coupled to a biological function of lymphocytes.

Anti-CD3-induced T-cell activation--II. Effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)

An in vivo model was used to examine the effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on various parameters of T-cell-activation. In this model, the hamster anti-mouse monoclonal antibody 145-2C11 (anti-CD3) to the CD3 portion of the murine T-cell receptor was injected into both rear footpads of female C57B1/6 mice and the draining popliteal and inguinal lymph node cells (LNC) were removed 24 h later. Cyclosporin A (CsA) was included as a known immunosuppressive control. As expected, CsA (50 mg/kg, i.p.) suppressed anti-CD3-induced proliferation, IL-2-driven 3H-TdR incorporation, and IL-2R expression. In contrast, TCDD unexpectedly enhanced anti-CD3-induced 3H-TdR incorporation. Flow cytometric analysis showed that TCDD treatment increased the percentage of both CD4+ and CD8+ cells cycling in S and G2M. LNC from TCDD-treated mice also had enhanced 3H-TdR incorporation when cultured in the presence of a saturating amount of exogenous mIL-2. TCDD did not significantly alter the percent positive or the number of IL-2 receptors (IL-2R) on either CD4+ or CD8+ cells when examined at several time points after anti-CD3 treatment. Both the kinetics and extent of anti-CD3-induced down-modulation of CD3 expression on CD4+ and CD8+ cells was unaffected by TCDD. TCDD alone did not result in enhanced 3H-TdR incorporation, cell cycling or IL-2R expression. Therefore, TCDD appears to be targeting T-cells that are undergoing activation rather than resting cells. The strength of the anti-CD3 model is evidenced by the fact that two known immunosuppressive compounds (CsA and TCDD) have distinct and opposite effects on T-cell activation. These findings suggest that the mechanism(s) by which CsA and TCDD impair T-cell function are different.