Is ß-catenin neutralization cross-involved in the mechanisms mediated by natalizumab action?

Aberrant activation of Wnt/ß-catenin signaling pathway is commonly associated to cancer development. However, molecular mechanisms controlling Wnt/ß-catenin signaling pathway have been clarified only in part. Here, we show that ß-catenin is differently modulated in patients with multiple sclerosis (MS), displaying that different pharmacological treatments used for clinical MS management cause different nuclear expression levels of ß-catenin. Proteins extracted by peripheral blood mononuclear cells were assessed to evaluate the western blot expression levels of ß-catenin. Analyzing our results, we realized that ß-catenin is totally inhibited by Natalizumab and could have a role in MS management. This could offer new promising studies focused on the possible therapeutic control of ß-catenin translocation.

Efficacy of very-low-dose betamethasone on neurological symptoms in ataxia-telangiectasia.

BACKGROUND: Ataxia-telangiectasia (A-T) is a non-curable neurodegenerative disorder, associated with progressive neurological dysfunction, oculocutaneous telangiectasia, immunodeficiency, predisposition to cancer and radiosensitivity. A recent study documented improvement in neurological symptoms after a short-term therapy with betamethasone in patients with A-T. Aim of this study was to evaluate the minimum therapeutically effective dosage of betamethasone on neurological symptoms of A-T. METHODS: Six responsive patients with A-T, received two 20-day cycles of oral betamethasone at 0.01 and 0.03 mg/kg/day (10% and 30% of the previously used full dosage), each followed by a 20-day washout period. Clinical and laboratory evaluations were carried out at T0 and at the end of each cycle. Neurological assessment was performed through the Scale for the Assessment and Rating of Ataxia (SARA). The glucocorticoid-induced leucine zipper (GILZ) and glucocorticoid receptor (GR) RNA expression were evaluated before and during the trial through real-time PCR. RESULTS: SARA scores significantly improved in all patients at the dosage of 0.03 mg/kg/day. In particular, three patients exhibited an improvement in 5/8 variables and two patients of 7 and 8 variables, respectively. Furthermore, the clinical improvement was already evident after the lower dosage. The basal GILZ and GR RNA expression were significantly lower in patients than in controls. GILZ expression increased in all patients after the beginning of the therapy, whereas no correlation between GR and the response was found. CONCLUSION: Our data indicate that betamethasone is effective in A-T at a minimal dosage and that GILZ may be a useful biomarker of the clinical response. This study provides Class IIIA evidence that betamethasone at very low dosage is effective in improving neurological signs of patients affected with ataxia-telangiectasia.

The glucocorticoid-induced TNF receptor family-related protein (GITR) is critical to the development of acute pancreatitis in mice.

BACKGROUND AND PURPOSE: Pancreatitis represents a life-threatening inflammatory condition where leucocytes, cytokines and vascular endothelium contribute to the development of the inflammatory disease. The glucocorticoid-induced tumour necrosis factor (TNF) receptor family-related protein (GITR) is a costimulatory molecule for T lymphocytes, modulates innate and adaptive immune system and has been found to participate in a variety of immune responses and inflammatory processes. Our purpose was to verify whether inhibition of GITR triggering results in a better outcome in experimental pancreatitis. EXPERIMENTAL APPROACH: In male GITR knock-out (GITR(-/-)) and GITR(+/+) mice on Sv129 background, acute pancreatitis was induced after i.p. administration of cerulein. Other experimental groups of GITR(+/+) mice were also treated with different doses of Fc-GITR fusion protein (up to 6.25 µg·mouse⁻¹), given by implanted mini-osmotic pump. Clinical score and pro-inflammatory parameters were evaluated. KEY RESULTS: A less acute pancreatitis was found in GITR(-/-) mice than in GITR(+/+) mice, with marked differences in oedema, neutrophil infiltration, pancreatic dysfunction and injury. Co-treatment of GITR(+/+) mice with cerulein and Fc-GITR fusion protein (6.25 µg·mouse⁻¹) decreased the inflammatory response and tissue injury, compared with treatment with cerulein alone. Inhibition of GITR triggering was found to modulate activation of nuclear factor κB as well as the production of TNF-α, interleukin-1ß, inducible nitric oxide synthase, nitrotyrosine, poly-ADP-ribose, intercellular adhesion molecule-1 and P-selectin. CONCLUSIONS AND IMPLICATIONS: The GITR-GITR ligand system is crucial to the development of acute pancreatitis in mice. Our results also suggest that the Fc-GITR fusion protein could be useful in the treatment of acute pancreatitis.

Involvement of cPLA2 inhibition in dexamethasone-induced thymocyte apoptosis.

Various molecular mechanisms have been suggested to be involved in dexamethasone induced thymocyte apoptosis. In this study we show that pharmacological inhibition of cytoplasmic PLA2 in mouse thymocytes for 18 h with arachidonyl trifluoromethyl ketone (AACOCF3) (10 microM) and palmitoyl trifluoromethyl ketone (PACOCF3) (10 microM) induced a drastic increase of thymocyte apoptosis comparable to that observed following Dex (10(-7) M) treatment, while inhibition of secretory PLA2 with p-bromophenacyl bromide (pBPB) (20 microM) did not. AACOCF3-induced thymocyte apoptosis, similarly to Dex-induced thymocyte apoptosis, was eliminated by cell pre-treatment with the PI-PLCbeta inhibitor, U73122, but not by the PC-PLC inhibitor D609. These observations were corroborated by the ability of AACOCF3, like Dex, to induce a rapid and transient increase in DAG generation. In addition, AACOCF3-induced apoptosis involved the activation of the acidic sphingomyelinase (aSMase) but not of the neutral sphingomyelinase (nSMase), as evaluated by measurements of enzyme activity in cell extracts following thymocyte exposure to AACOCF3 and by the ability of monensin to inhibit AACOCF3-induced thymocyte apoptosis. In addition, the AACOCF3 apoptotic effect resulted in an early increase of ceramide levels. AACOCF3-induced thymocyte apoptosis involved the activation of caspase 3, and cell pre-treatment with a caspase 3 inhibitor prevented AACOCF3-induced apoptosis. These observations suggest that cPLA2 inhibition may have a role in Dex-induced thymocyte apoptosis and highlight the importance of cPLA2 activity in thymocyte survival.

Endothelial dysfunction in vivo is related to monocyte resistin mRNA expression.

BACKGROUND: Resistin could be the linkage between the adipose tissue and the insulin resistance. In humans, the role of resistin on metabolic and vascular homeostasis is not well defined. The aim of this study was to investigate the possible association between resistin expression and insulin resistance. METHODS AND RESULTS: We evaluated the relationship between monocyte expression of mRNA and anthropometric and metabolic parameters of insulin resistance. We focused on the potential role of resistin on endothelial function. Thirty-nine patients with metabolic syndrome (MS) and clinically free from cardiovascular disease, and 15 healthy subjects were included in this study. All subjects underwent clinical examination, assessment of haematochemical parameters, bioimpedentiometry, measurement of monocyte resistin mRNA and of brachial-artery flow-mediated vasodilation (FMV). Patients with MS showed higher levels of interleukin-6 (IL; 2.1 +/- 1.2 vs. 1.2 +/- 0.9 pg/mL, P < 0.05) and reduced FMV (5.4 +/- 3.9 vs. 8.3 +/- 3.1%, P < 0.05). The subjects were divided into two groups: (i) subjects with high expression mRNA resistin levels and (ii) subjects with low or not detectable; Group 1 was younger (50 +/- 13 vs. 59 +/- 11 years, P = 0.01), showed higher IL-6 values (2.3 +/- 1.2 vs. 1.6 +/- 1.2, P = 0.03) and lower values of FMV (4.3 +/- 2.8 vs. 7.4 +/- 3.9%, P = 0.003). With univariate analysis monocyte mRNA showed a significant positive correlation with waist circumference (r = 0.27, P < 0.05) and IL-6 (r = 0.26, P < 0.05) and a negative correlation with FMV (r = -0.38, P < 0.005). With multivariate regression analysis brachial-artery diameter, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, IL-6 and RNAm resistin expression were independent predictors of reduced FMV. CONCLUSIONS: mRNA resistin negatively influences FMV, and is a possible in vivo index of endothelial dysfunction.

GITR modulates innate and adaptive mucosal immunity during the development of experimental colitis in mice.

BACKGROUND: Uncontrolled T cell activation and abnormal function of the innate immune system against normal enteric bacterial flora play a critical part in the pathogenesis of inflammatory bowel disease (IBD). Therefore, pharmacological strategies directed to restore the normal responsiveness of the immune system could be efficacious in the treatment of these pathological conditions. Glucocorticoid-induced tumour necrosis factor receptor (GITR)-related gene is a member of the tumour necrosis factor receptor superfamily that is constitutively expressed at high levels on regulatory T cells and at low levels on unstimulated T cells, B cells and macrophages. GITR triggering leads to activation of T effectors and reversal of suppressive function of regulatory T cells. AIM: To investigate the role of GITR in the development of experimental colitis in mice. RESULTS: Using GITR(-/-) mice, GITR deletion protected against 2,4,6-trinitrobenzene sulphonic acid (TNBS)-induced colitis by reducing innate immune responses and effector T cell activity. Effector T cells isolated from GITR(-/-) mice were less effective than T cells isolated from GITR(+/+) mice to transfer colitis in immunodeficient mice. Blocking the GITR/ligand for GITR (GITRL) signal by giving soluble GITR prevented TNBS-induced colitis in normal GITR(+/+) and also in lymphocyte-deficient SCID mice. CONCLUSIONS: Collectively, these data suggest that GITR plays a critical part in regulating both acquired and innate mucosal immune responses during the development of experimental colitis in mice. Therefore, targeting the GITR/GITRL system signalling may represent a potential pharmacological tool for the treatment of IBD.

Induction of apoptosis by 1,4-benzothiazine analogs in mouse thymocytes.

1,4-benzothiazine (1,4-B) derivatives exert numerous effects in vivo and in vitro, including neurotoxicity and antitumor cytotoxicity. To analyze the mechanisms responsible for 1,4-B-induced cytotoxicity, we performed experiments to evaluate the possible apoptotic effect. For that purpose, we used mouse thymocytes, a cell population well sensitive to induction of apoptosis that has been used to assay apoptosis in many experimental systems. Results indicate that a number of 1,4-B analogs are able to induce both thymocyte apoptosis in vitro and thymus cell loss in vivo. Moreover, analysis of the structure-activity relationship indicate that the sulfur (S) oxidation state, the presence of the carbonyl group, and the nature and position of the side chain modulate the apoptotic efficacy. Moreover, results of in vitro experiments show that the 1,4-B-induced apoptosis associates with different biochemical events including phosphatidylcholine-specific phospholipase C activation, acidic sphingomyelinase activation and ceramide generation, loss of mitochondrial membrane potential (DeltaPsi(m)) and cytochrome c release, and caspase-8, -9, and -3 activation. These results indicate that 1,4-B analogs induce apoptosis through a complex of biochemical events.

Modulation of T-cell activation by the glucocorticoid-induced leucine zipper factor via inhibition of nuclear factor kappaB.

Previously a novel gene was identified that encodes a glucocorticoid-induced leucine zipper (GILZ) whose expression is up-regulated by dexamethasone. This study analyzed the role of GILZ in the control of T-cell activation and its possible interaction with nuclear factor kappaB (NF-kappaB). Results indicate that GILZ inhibits both T-cell receptor (TCR)-induced interleukin-2/interleukin-2 receptor expression and NF-kappaB activity. In particular, GILZ inhibits NF-kappaB nuclear translocation and DNA binding due to a direct protein-to-protein interaction of GILZ with the NF-kappaB subunits. Moreover, GILZ-mediated modulation of TCR-induced responses is part of a circuit because TCR triggering down-regulates GILZ expression. These results identify a new molecular mechanism involved in the dexamethasone-induced regulation of NF-kappaB activity and T-cell activation. (Blood. 2001;98:743-753)

Differentiation of Ly49s-positive or -negative natural killer cells is inhibited by anti-H-2b monoclonal antibodies acting at the level of bone marrow progenitors from B6 mice.

To investigate the role of MHC class I on in vitro differentiation of natural killer (NK) cells, a CD44low/-CD2-classlow population was isolated from mouse bone marrow. This population, which lacked expression of NK-1.1, Ly49A, Ly49C/I, and Ly49G, generated populations of NK-1.1+ NK cells expressing Ly49A, Ly49C/I, or Ly49G when cocultured for 13 days with syngeneic supportive stromal cells in the presence of interleukin 2. Ly49A and Ly49C/I were absent on the progeny of progenitors tested after 7 days of culture but were expressed as a late event together with low-level expression of NK-1.1, from day 8 of culture. The addition of anti-H-2b monoclonal antibody to cultures at day 0 inhibited proliferation of progenitors supported by either syngeneic, allogeneic, or H-2b-deficient stromal cells, thus suggesting that the effect was not exerted on stromal cells. Additional analyses demonstrated that class Ilow progenitors generated class I+ cells on which the anti-H-2b monoclonal antibody exerted its inhibitory effect.

IL-2-driven natural killer cell generation: role of anti-H-2b monoclonal antibodies and stromal cells in controlling quantitative and repertoire changes.

To investigate the role of major histocompatibility complex class I and bone marrow stromal cells on in vitro differentiation of natural killer cells, a CD44(low/-) CD2- population was isolated from mouse bone marrow. This NK-1.1- CD3- LFA-3+ B220+ population, when stimulated with IL-2 and co-cultured with supportive syngeneic stromal cells, generated populations of NK-1.1+ Ly49A+ Ly49C/I+ CD3- mature natural killer cells. The effect of anti-H-2b monoclonal antibodies (mAbs) on this phenomenon was assayed. Pre-adhesion of anti-H-2b mAbs to the stromal cells did not exert any effect, whereas when the same mAbs were pre-adhered to progenitors, there was a inhibition of natural killer cell generation that was maximum when the mAbs were added directly to cultures. In addition, the anti-H-2b mAbs did not inhibit the IL-2-induced proliferation of mature natural killer cells. Allogeneic but not H-2b-deficient stromal cells decreased the expression of Ly-49C/I but not Ly49A, thus suggesting that stromal cell haplotypes qualitatively influence the expression of Ly49s repertoire.

Effect of interleukin-2 on generation of natural killer cells: role of major histocompatibility complex class I in B6 and TAP-1-/- mice.

Long-term bone marrow cultures were used to investigate the effect of IL-2, a cytokine widely used in immunotherapy, on natural killer cell differentiation. Specifically, the role of MHC was evaluated by comparing normal B6 and class I-deficient TAP-1-/- mice. The number of cells generated after a 13-day culture was the same in cell cultures from TAP-1-/- or B6 mice but the relative number of natural killer cells, identified as NK-1.1+CD3- cells by flow cytometry analysis, was increased in TAP-1-/- compared to B6 cultures (74.4% and 63.9%, respectively). Addition of an anti-class I mAb determined a strong inhibition of natural killer cell generation in B6 cultures, and its effect was specific since no effect was seen in TAP-1-/- cell cultures. TAP-1-/- natural killer cells or the few natural killer cells escaping the inhibitory effect of anti-class I mAb, were less cytotoxic than total B6 natural killer cells against target cell lines of different haplotype.

A new dexamethasone-induced gene of the leucine zipper family protects T lymphocytes from TCR/CD3-activated cell death.

By comparing mRNA species expressed in dexamethasone (DEX)-treated and untreated murine thymocytes, we have identified a gene, glucocorticoid-induced leucine zipper (GILZ), encoding a new member of the leucine zipper family. GILZ was found expressed in normal lymphocytes from thymus, spleen, and lymph nodes, whereas low or no expression was detected in other nonlymphoid tissues, including brain, kidney, and liver. In thymocytes and peripheral T cells, GILZ gene expression is induced by DEX. Furthermore, GILZ expression selectively protects T cells from apoptosis induced by treatment with anti-CD3 monoclonal antibody but not by treatment with other apoptotic stimuli. This antiapoptotic effect correlates with inhibition of Fas and Fas ligand expression. Thus, GILZ is a candidate transcription factor involved in the regulation of apoptosis of T cells.