Fabio Benigni

Clonal Anergy Is Maintained Independently of T Cell Proliferation

Ag encounter in the absence of proliferation results in the establishment of T cell unresponsiveness, also known as T cell clonal anergy. Anergic T cells fail to proliferate upon restimulation because of the inability to produce IL-2 and to properly regulate the G1 cell cycle checkpoint. Because optimal TCR and CD28 engagement can elicit IL-2-independent cell cycle progression, we investigated whether CD3/CD28-mediated activation of anergic T cells could overcome G1 cell cycle block, drive T cell proliferation, and thus reverse clonal anergy. We show here that although antigenic stimulation fails to elicit G1-to-S transition, anti-CD3/CD28 mAbs allow proper cell cycle progression and proliferation of anergic T cells. However, CD3/CD28-mediated cell division does not restore Ag responsiveness. Our data instead indicate that reversal of clonal anergy specifically requires an IL-2-dependent, rapamycin-sensitive signal, which is delivered independently of cell proliferation. Thus, by tracing proliferation and Ag responsiveness of individual cells, we show that whereas both TCR/CD28 and IL-2-generated signals can drive T cell proliferation, only IL-2/IL-2R interaction regulates Ag responsiveness, indicating that proliferation and clonal anergy can be independently regulated.

VDR‐dependent regulation of mast cell maturation mediated by 1,25‐dihydroxyvitamin D3

1,25‐Dihydroxyvitamin D3 [1,25(OH)2D3] is a secosteroid hormone that regulates bone metabolism, controls calcium homeostasis, and possesses immunomodulatory properties. We show here that 1,25(OH)2D3 contributes to the regulation of development and function of mast cells, which play a critical role in several inflammatory disorders. 1,25(OH)2D3 promotes apoptosis and inhibits maturation of mouse bone marrow‐derived mast cell precursors. Dose‐dependent inhibition of mast cell differentiation by 1,25(OH)2D3 is observed at discrete, intermediate stages of mast cell development, identified by expression of c‐kit, FcεRI, and IL‐3 receptor‐α chain, and depends on the expression of the vitamin D receptor (VDR). It is important that mast cell progenitors obtained from VDR‐ablated mice undergo an accelerated maturation in vitro and give rise to more responsive mast cells than wild‐type. Furthermore, histological analysis of mast cell density in peripheral tissues reveals a moderate increase in the number of mast cells in the skin of VDR‐deficient mice compared with wild‐type animals. These data support the hypothesis of a physiological role of 1,25(OH)2D3 in mast cell development and suggest novel, therapeutic uses of 1,25(OH)2D3 analogs.

Expression of Fatty Acid Amide Hydrolase (FAAH) in Human, Mouse, and Rat Urinary Bladder and Effects of FAAH Inhibition on Bladder Function in Awake Rats.

BACKGROUND Cannabinoid receptor (CB)-mediated functions may be involved in the regulation of bladder function, but information on endocannabinoid signals during micturition is scarce. OBJECTIVE Investigate the expression of the endocannabinoid-degrading enzyme fatty acid amide hydrolase (FAAH) in human, rat, and mouse bladders and study the effects of inhibition of FAAH during urodynamics in awake rats. DESIGN, SETTING, AND PARTICIPANTS Bladder tissue from humans, mice, and rats was used for measurements. Female Sprague-Dawley rats were administered the FAAH inhibitor oleoyl ethyl amide (OEtA) or vehicle intravenously (IV) or intravesically (IVES) with or without rimonabant (CB1 antagonist) or SR144528 (CB2 antagonist). MEASUREMENTS Real-time transcriptase-polymerase chain reaction, Western blot, immunohistochemistry, and cystometry in awake rats. RESULTS AND LIMITATIONS Messenger RNA and protein for FAAH was expressed in the mucosa of human, mouse, and rat urinary bladders. Immunoreactivities for FAAH and CB2 were codistributed in rat and human urothelium. IV OEtA (0.3mg/kg) to rats increased intercontraction intervals (ICIs), micturition volume (MV), bladder capacity (BC), and threshold pressure (TP) by 17±1%, 16±1%, 17±1%, and 19±5%, respectively (all p<0.05 vs baseline). IVES OEtA (1 and 10mg/l) in rats dose-dependently increased (p<0.05 vs baseline) ICI (19±2% and 35±5%), MV (15±3% and 32±4%), BC (16±2% and 34±4%), and TP (15±1%, 21±3%). SR144528 (IVES 5mg/l) abolished all effects of OEtA, whereas rimonabant only counteracted effects of OEtA on TP. CONCLUSIONS Bladder mucosa of all species expressed FAAH. Rat and human urothelium coexpressed FAAH and CB2. The FAAH inhibitor OEtA altered urodynamic parameters that reflect sensory functions of micturition in rats. Suggesting a role for the endocannabinoid system in bladder mechanoafferent functions of rats, effects of IVES OEtA were abolished by an IVES CB2 antagonist and partly counteracted by an IVES CB1 antagonist.

Phenotype and Homing of CD4 Tumor-Specific T Cells Is Modulated by Tumor Bulk

Technical difficulties in tracking endogenous CD4 T lymphocytes have limited the characterization of tumor-specific CD4 T cell responses. Using fluorescent MHC class II/peptide multimers, we defined the fate of endogenous Leishmania receptor for activated C kinase (LACK)-specific CD4 T cells in mice bearing LACK-expressing TS/A tumors. LACK-specific CD44highCD62Llow CD4 T cells accumulated in the draining lymph nodes and had characteristics of effector cells, secreting IL-2 and IFN-γ upon Ag restimulation. Increased frequencies of CD44highCD62Llow LACK-experienced cells were also detected in the spleen, lung, liver, and tumor itself, but not in nondraining lymph nodes, where the cells maintained a naive phenotype. The absence of systemic redistribution of LACK-specific memory T cells correlated with the presence of tumor. Indeed, LACK-specific CD4 T cells with central memory features (IL-2+IFN-γ−CD44highCD62Lhigh cells) accumulated in all peripheral lymph nodes of mice immunized with LACK-pulsed dendritic cells and after tumor resection. Together, our data demonstrate that although tumor-specific CD4 effector T cells producing IFN-γ are continuously generated in the presence of tumor, central memory CD4 T cells accumulate only after tumor resection. Thus, the continuous stimulation of tumor-specific CD4 T cells in tumor-bearing mice appears to hinder the systemic accumulation of central memory CD4 T lymphocytes.

The Immunogenicity of Dendritic Cell-Based Vaccines Is Not Hampered by Doxorubicin and Melphalan Administration

Immunization of cancer patients is most effective in tumor-free conditions or in the presence of minimal residual disease. In the attempt to develop new strategies able to control tumor recurrence while allowing the development of protective immunity, we have investigated the immunogenic potential of two distinct vaccine formulations when provided alone or upon single and repeated treatment with chemotherapeutics drugs. Vaccine-induced T cell responses were first investigated by tracing Ag-specific T cell responses in mice bearing detectable frequencies of Ag-specific TCR transgenic CD4 and CD8 T cells. These studies indicated that immunization with peptide-pulsed dendritic cells and soluble Ag plus adjuvant elicited a comparable expansion and differentiation of CD4 and CD8 effector cells in the peripheral lymphoid tissues when provided alone or shortly after Doxorubicin or Melphalan administration. We also analyzed the potency of the combined vaccination in transgenic adenocarcinoma mouse prostate mice, which develop spontaneous prostate cancer. Dendritic cell-based vaccination elicited potent tumor-specific cytotoxic responses in mice bearing prostate intraepithelial neoplasia both in the absence and in the presence of Doxorubicin. Together our results indicate that Doxorubicin- or Melphalan-based chemotherapy and Ag-specific vaccination can be combined for adjuvant treatments of cancer patients.

Peripheral Effects of Centrally Administered Interleukin-1β in Mice in Relation to Its Clearance from the Brain into the Blood and Tissue Distribution

Administration of interleukin IL-1 induces acute-phase response and inhibition of gastric secretion more efficiently when administered intracerebroventricularly (i.c.v.) than when the same dose of IL-1 is administered systemically. In this study we describe the pharmacokinetics of IL-1β, administered centrally or systemically, in the serum or in peripheral tissues. IL-1β administered i.c.v. resulted in higher peak IL-1β concentrations, and lasted longer, than intravenous (i.v.) or intraperitoneal (i.p.) administration. Higher IL-1β levels in the liver and heart were observed after i.c.v. administration (compared to the i.p. or i.v. route). Our data suggest that centrally injected IL-1 induces higher circulating and hepatic IL-1 levels and contributes to the fact that the i.c.v. route of administration is particularly effective in inducing a liver acute-phase response.

Mechanism of inhibition of tumor necrosis factor production by chlorpromazine and its derivatives in mice

In previous work, we reported that chlorpromazine inhibits tumor necrosis factor (TNF) production in endotoxin lipopolysaccharide-treated mice, and protects against lipopolysaccharide toxicity. Chlorpromazine is used as an antipsychotic and has several effects on the central nervous system. It acts on different neurotransmitter receptors and has other biochemical activities some of which, like inhibition of phospholipase A2, might be responsible for the inhibitory effect on TNF production. To investigate the role of these actions in the inhibition of TNF production by chlorpromazine, we have synthesized some chlorpromazine derivatives that do not have central activities. Some of these analogs have lost their affinity for various receptors and their phospholipase A2 inhibitory activity, but still inhibit TNF production. No correlation was found between TNF inhibition and the ability to inhibit nitric oxide (NO) synthase, whereas a good correlation was evident between TNF inhibition and antioxidant activity.

Spinal Cord FAAH in Normal Micturition Control and Bladder Overactivity in Awake Rats

PURPOSE We assessed whether spinal inhibition of the cannabinoid degrading enzyme FAAH would have urodynamic effects in normal rats and rats with bladder overactivity induced by partial urethral obstruction or prostaglandin E2. We also determined the expression of FAAH, and the cannabinoid receptors CB1 and CB2 in the sacral spinal cord. MATERIALS AND METHODS We used 44 rats for functional (cystometry) and Western blot experiments. The FAAH inhibitor oleoyl ethyl amide (3 to 300 nmol) was administered intrathecally (subarachnoidally) or intravenously. The expression of FAAH and CB1/CB2 receptors was determined by Western blot. RESULTS Oleoyl ethyl amide given intrathecally affected micturition in normal rats and rats with bladder overactivity but effects were more pronounced in the latter. In normal rats oleoyl ethyl amide only decreased micturition frequency, while it decreased frequency and bladder pressures in rats with bladder overactivity. Intravenous oleoyl ethyl amide (3 to 300 nmol) had no urodynamic effect. FAAH and CB1/CB2 receptors were expressed in the rat sacral spinal cord. The expression of CB1/CB2 receptors but not FAAH was higher in obstructed than in normal rats. CONCLUSIONS FAAH inhibition in the sacral spinal cord by oleoyl ethyl amide resulted in urodynamic effects in normal rats and rats with bladder overactivity. The spinal endocannabinoid system may be involved in normal micturition control and it appears altered when there is bladder overactivity.

Effects of the Gonadotropin-Releasing Hormone Antagonist Ganirelix on Normal Micturition and Prostaglandin E-2-Induced Detrusor Overactivity in Conscious Female Rats

BACKGROUND Gonadotropin-releasing hormone (GnRH) antagonists have been reported to have beneficial effects on lower urinary tract symptoms in patients with benign prostatic hyperplasia. OBJECTIVE Our aim was to investigate the effects of ganirelix, a GnRH receptor antagonist, on bladder function and detrusor overactivity (DO) in female rats. DESIGN, SETTING, AND PARTICIPANTS Female Sprague-Dawley rats received 2 wk of daily systemic (0.1 mg/kg) or acute intravesical administration (IVES; 0.14 mg/l or 1.4 mg/l) ganirelix or vehicle (controls). MEASUREMENTS Assessments were obtained using cystometry in awake rats, organ bath studies, enzyme-linked immunosorbent assay, and western blot (WB). RESULTS AND LIMITATIONS Luteinising hormone levels were lower in rats treated systemically with ganirelix than in controls. No differences were observed in body or bladder weights. Micturition interval (MI), micturition volume (MV), residual volume, and bladder capacity (BC) were similar in both groups at baseline. No differences in urodynamic pressure parameters were observed between groups at baseline. Intravesical prostaglandin E(2) reduced MI, MV, and BC, and it increased basal pressure (BP), threshold pressure (TP), flow pressure (FP), and maximum pressure (MP) in all rats. MI, MV, and BC were reduced by 43%±4%, 50%±4%, and 43%±4% (controls) versus 22%±3%, 23%±3%, and 21%±3% (ganirelix-treated rats; p<0.001). TP and FP increased by 38%±8% and 30%±4% (controls) versus 16%±7% and 16%±5% (ganirelix; p<0.05). The maximal force of contractions for carbachol was larger in detrusor from ganirelix-treated rats (231% vs 177% of 60 mM K+-induced contractions). At 0.14 mg/l, but not 0.14 mg/l, IVES ganirelix increased MI, MV, and BC and decreased BP, TP, FP, and MP. In vitro, ganirelix had no effect on detrusor function. The gonadotropin-releasing hormone receptor was expressed (by WB) in the bladder mucosa. CONCLUSIONS Systemic treatment with ganirelix counteracted experimental DO in female rats. Because bladder preparations from these rats exhibited larger contractions to carbachol and because intravesical ganirelix affected both micturition intervals and urodynamic pressure profiles, a peripheral site of action of ganirelix in the urinary bladder cannot be excluded.

The fatty acid amide hydrolase inhibitor oleoyl ethyl amide counteracts bladder overactivity in female rats

To study micturition and bladder overactivity in female rats after chronic treatment with the fatty acid amide hydrolase (FAAH) inhibitor oleoyl ethyl amide (OEtA).