Cell-activating Cytokines Research Articles

Suppression of T cell functions by hydroxamic acid-based histone deacetylase inhibitors

Histone deacetylase inhibitors (HDACis) have recently been shown to suppress inflammatory responses at much lower concentrations than that the concentrations that produce an antitumor effect. In the current study, the inhibitory activity of T cell functions by three different HDACis was compared, and the mechanisms underlying the inhibitory activity were demonstrated. Trichostatin-A (TSA) and scriptaid (ST) had potent inhibitory effects on the proliferation of T cells. TSA suppressed the synthesis of the T cell-activating cytokine, interleukin (IL)-2, and the T cell-derived cytokines, interferon (IFN)-γ, IL-4, and IL-13. In addition, TSA induced inhibition of cell cycle progression and IL-2 receptor expression. On the whole, TSA had a stronger effect on T cell functions than other HDACis. Similarly, a longer duration of hyperacetylation was observed in the cells that had been exposed to TSA. Thus, the inhibition of histone deacetylation appears to be related to the inhibitory effect of TSA. These results are expected to serve as a guide for future studies on the ability of HDACis to inhibit acute and chronic inflammatory diseases provoked by T cells.

Interleukin-15 enhances rituximab-dependent cytotoxicity against chronic lymphocytic leukemia cells and overcomes transforming growth factor beta-mediated immunosuppression

Chemoimmunotherapy with anti-CD20 monoclonal antibody rituximab is increasingly used for the treatment of patients with chronic lymphocytic leukemia (CLL). Antibody-dependent cytotoxicity (ADCC) is one of the most important mechanisms of action of rituximab against B-cell malignancies. We studied ways to increase the cytotoxic effect of rituximab on CLL cells by enhancing ADCC. Peripheral blood mononuclear cell (PBMC) or purified natural killer (NK) cells from healthy donors were activated with interleukin-15 (IL-15) and cultured with rituximab-coated CLL cells, and ADCC was evaluated using a (51)chromium release assay. The IL-15 significantly enhanced invitro ADCC against CLL cells, and this effect was mainly mediated by NK cells. The IL-15 treated effector cells with the low affinity FcγRIIIA receptor (158FF) had an ADCC comparable to those with the high affinity FcγRIIIA form (158VF). Inaddition, IL-15 enhanced rituximab-mediated ADCC of CLL cells in the presence of transforming growth factor-beta. The IL-15 increases rituximab-mediated ADCC against CLL, and supports the use of such agents with the goal of improving clinical response to chemoimmunotherapy in patients with CLL.

IL-12 Enhances the Antitumor Actions of Trastuzumab via NK Cell IFN-γ Production

The antitumor effects of therapeutic mAbs may depend on immune effector cells that express FcRs for IgG. IL-12 is a cytokine that stimulates IFN-γ production from NK cells and T cells. We hypothesized that coadministration of IL-12 with a murine anti-HER2/neu mAb (4D5) would enhance the FcR-dependent immune mechanisms that contribute to its antitumor activity. Thrice-weekly therapy with IL-12 (1 μg) and 4D5 (1 mg/kg) significantly suppressed the growth of a murine colon adenocarcinoma that was engineered to express human HER2 (CT-26(HER2/neu)) in BALB/c mice compared with the result of therapy with IL-12, 4D5, or PBS alone. Combination therapy was associated with increased circulating levels of IFN-γ, monokine induced by IFN-γ, and RANTES. Experiments with IFN-γ-deficient mice demonstrated that this cytokine was necessary for the observed antitumor effects of therapy with IL-12 plus 4D5. Immune cell depletion experiments showed that NK cells (but not CD4(+) or CD8(+) T cells) mediated the antitumor effects of this treatment combination. Therapy of HER2/neu-positive tumors with trastuzumab plus IL-12 induced tumor necrosis but did not affect tumor proliferation, apoptosis, vascularity, or lymphocyte infiltration. In vitro experiments with CT-26(HER2/neu) tumor cells revealed that IFN-γ induced an intracellular signal but did not inhibit cellular proliferation or induce apoptosis. Taken together, these data suggest that tumor regression in response to trastuzumab plus IL-12 is mediated through NK cell IFN-γ production and provide a rationale for the coadministration of NK cell-activating cytokines with therapeutic mAbs.

Minocycline Differentially Modulates Viral Infection and Persistence in an Experimental Model of Japanese Encephalitis

Japanese encephalitis (JE) is caused by a neurotropic flavivirus that causes CNS damage that leads to death in acute cases or permanent neuropsychiatric sequel in survivors. The course of infection of this virus is not well defined though it is clear that it evades the host's innate immune response in the periphery. The current study was designed to investigate the time-dependent changes in the spleen and lymph node, apart from the CNS that are infected by the Japanese encephalitis virus (JEV). Our previous studies have led to the identification of minocycline, a semi-synthetic antibiotic, as a protective drug in JE. In this study we have also investigated the role of minocycline on the peripheral organs that are infected by JEV. Levels of IL-12 and MCP-1 in the organs were estimated by cytometric bead array, and immunohistochemical studies were performed on cryosections of tissue to detect CD3- or CD11b-positive cells as well as JEV antigen. We found that the levels of T cell-activating cytokine IL-12 and MCP-1 levels were significantly elevated in JEV-infected tissue samples in a time-dependent manner. Corresponding to this increase was the increase in the number of CD3- and CD11b-positive cells in the tissues of infected animals. Minocycline treatment abrogated these changes. Minocycline treatment also resulted in the gradual decrease in the number of CD11b (but not CD3) positive cells in the lymph node and spleen, even though the virus persisted in these organs. We also observed structural changes in the spleen following minocycline treatment.

Anti-inflammatory property of the cannabinoid receptor-2-selective agonist in spinal cord injury (35.11)

Abstract Recently cannabinoids are being studied in treatment of various animal models of CNS disorders such as MS, AD, PD and stroke. They are also being used in treating neuropathic pain in patients with spinal cord injury (SCI). Two cannabinoid receptors have been cloned; CB1, mainly expressed in the CNS and CB2, predominantly expressed in the periphery including immune cells. Previous studies from our laboratory showed that treatment with the CB2 specific agonist O-1966 improved recovery of motor and bladder function in mouse model of acute spinal cord injury. In SCI, increased infiltration and activation of inflammatory immune cells that follow the initial injury exacerbate neuronal damage. In this study we analyzed expression of inflammatory molecules that serve as markers for activation and infiltration of immune cells and their modulation by the CB2 agonist treatment. A murine thoracic spinal cord contusion model of SCI was used and spinal cords were analyzed for expression of various cytokines and chemokines. We found suppression of a number of molecules in spinal cords that were subjected to the CB2 agonist treatment. There was decreased expression of the CXCL family chemokine members CXCL1, 2, 3, 9 and 11, the CC family chemokine members CCL 8, 11, 20, T cell activation cytokines: IFN-γ, IL-23, IL-22 and some of the Toll-like receptors such as TLR1, 4, 6, and 7. Thus, it appears that CB2 agonist treatment may aid in recovery in acute SCI via its immunomodulating effects.

Lessons from Viral Latency in T Cells: Manipulating HIV-1 Transcription by Sirna

Despite prolonged and intensive application, currently available combined antiretroviral therapy cannot eradicate HIV-1. It has little impact on provirus harbored within resting CD4+ T cells, which survive for long periods of time. One approach to clear this reservoir has been to administer either T cell-activating cytokines or histone deacetylase inhibitors to HIV-1 infected individuals in order to reactivate latent virus from the cellular compartment while continuing cART to avoid reseeding of the reservoir. These approaches have had limited success. Strategies for the eradication of HIV need to be refined. Rational design of these approaches requires a clear understanding of the determinants of viral latency, which is controlled, at least in part, by epigenetic modifications in histones and recruitment of suppressive proteins to form heterochromatin in the promoter region of the virus. Reactivation of virus correlates with dissociation of repressive modifications, including acetylation of histone tails. siRNA has been found to be capable of inducing heterochromatin formation. Prolonged HIV-1 transcriptional gene silencing induced by either RNA duplexes or retrovirally delivered shRNA targeting a sequence located within the HIV-1 promoter is associated with sustained RNA induction and maintenance of heterochromatin (closed) structure in the viral promoter. These changes resemble those described in the latent infection. Observations regarding epigenetic control of viral transcription may provide important insights into mechanisms to manipulate latent viral reservoirs.

Release of B Cell‐Activating Factor of the TNF Family in Bronchoalveolar Lavage from Behçet Disease with Pulmonary Involvement

Pulmonary artery aneurysms, arterial and venous thrombosis, pulmonary infarction, recurrent pneumonia, bronchiolitis obliterans organized pneumonia, and pleurisy are the main features of pulmonary involvement in Behçet's disease. The objective of this study was to investigate the production of B cell-activating factor of the TNF family (BAFF), an important regulator of B-cell survival and immunoglobulin class-switch recombination, in bronchoalveolar lavage (BAL) fluid from BD patients having pulmonary manifestation. Bronchoalveolar lavage (BAL) was performed in 15 BD patients with pulmonary manifestation and 18 BAL from healthy controls. Concentrations of B cell-active cytokines, including BAFF, IL-6, and IL-13, were measured by using specific ELISA and cytometric bead array assays. Levels of BAFF protein were significantly increased in BAL fluid from active BD [109 +/- 21.78 pg/mL] compared with those oh healthy controls [4.83 +/- 1.75 pg/mL; P<0.0001]. In the BAL fluid, BAFF levels were significantly correlated with absolute numbers of total cells [r = 0.823; P<0.0001], lymphocytes [r = 0.709; P<0.0001], neutrophils [r = 0.809; P<0.0001] and macrophages [r = 0.742; P<0.0001]. Normalization to albumin indicated that BAFF production occurred locally in the airways. BAFF levels were also significantly correlated with the other B cell-activating cytokines IL-6 [r = 0.882, P<0.001] and IL-13 [r = 0.659, P<0.001].The antigen-induced production of BAFF in the lung of active BD with pulmonary manifestations might contribute to immunoglobulin synthesis by B cells. The cells residing in the lung might affect each other through BAFF.

Post‐consolidation Immunotherapy with Histamine Dihydrochloride and Interleukin‐2 in AML

The initial chemotherapy in acute myeloid leukaemia (AML) comprises a first phase of induction and a second phase of consolidation. In the majority of patients, the induction treatment leads to complete remission (CR), defined as microscopic disappearance of leukaemic disease along with the return of normal haematopoiesis. However, despite the introduction of more efficacious consolidation regimens, a worryingly large proportion of AML patients in CR will subsequently experience relapses with poor prospects of long-term survival. A relapse is assumed to be the result of expansion of residual leukaemic cells that have escaped the initial chemotherapy. The anti-leukaemic functions of T cells and natural killer (NK) cells has formed the background to the use of interleukin-2 (IL-2), a T- and NK cell-activating cytokine, with the aim to eliminate residual leukaemia and hence reduce the relapse rate in AML, but the clinical trials using IL-2 monotherapy have yielded disappointment. A recent phase III study has demonstrated that post-consolidation treatment with the combination of histamine dihydrochloride (HDC) and IL-2 significantly prevents relapse in AML patients. Here we account for the preclinical background to the use of HDC/IL-2 in AML along with a review of clinical results.

Differential effects ofStaphylococcalenterotoxin B-mediated immune activation on intestinal defensins

In the small intestine members of both the alpha-defensin (DEFA5 and DEFA6) and beta-defensin (DEFB1 and DEFB2) family contribute to the anti-microbial barrier against infection. The aim of this study was to determine whether Staphylococcal enterotoxin B (SEB)-mediated immune activation and proinflammatory cytokines play a role in the regulation of intestinal defensin expression. Defensin mRNA and peptide secretion was studied after ex vivo tissue culture of duodenal biopsies over 24 h. Immune (T cell and macrophage) activation was induced by SEB, and in separate experiments exogenous proinflammatory cytokines were added individually. Defensin mRNA levels were quantified by reverse transcription-polymerase chain reaction, and peptide release into culture supernatants was quantified by immuno dot blot or enzyme-linked immunosorbent assay. Increasing concentrations of SEB down-regulated DEFA5, DEFA6 and DEFB1 mRNA in a dose-dependent manner but increased DEFB2 simultaneously. The down-regulation of alpha-defensins was reversed by dexamethasone. DEFA5 and DEFB2 peptide secretion levels were altered in parallel with mRNA. Interferon-gamma and interleukin (IL)-1beta exhibited a dose-dependent down-regulation of alpha-defensin mRNA, IL-6 significantly down-regulated only DEFA6; in contrast, tumour necrosis factor-alpha and IL-4 had no significant effect. Immune cell activation and proinflammatory cytokines down-regulated the constitutively expressed DEFA5, DEFA6 and DEFB1 defensins, and up-regulated DEFB2 in intact human intestinal tissue explants in short-term culture. The effect of local immune activation on innate defence may explain the reduced alpha-defensin expression noted in inflammatory T cell-mediated enteropathies.

Local release of B cell–activating factor of the TNF family after segmental allergen challenge of allergic subjects

Local production of IgA and IgE in the airways has been proposed to be an important event in both immune protection from pathogens and the pathogenesis of airway allergic diseases. The objective of this study was to investigate the production of B cell-activating factor of the TNF family (BAFF), an important regulator of B-cell survival and immunoglobulin class-switch recombination, in bronchoalveolar lavage (BAL) fluid after segmental allergen challenge of allergic subjects. Segmental allergen challenge with saline or allergen was performed in 16 adult allergic subjects. BAL was performed at both saline- and allergen-challenged sites 20 to 24 hours after challenge. Concentrations of B cell-active cytokines, including BAFF, IL-6, and IL-13, were measured by using specific ELISA and cytometric bead array assays. Levels of BAFF protein were significantly increased in BAL fluid after allergen challenge (53.8 pg/mL [range, 0-407.4 pg/mL], P = .001) compared with those at saline-challenged sites (0 pg/mL [0-34.7 pg/mL]). In the BAL fluid after allergen challenge, BAFF levels were significantly correlated with absolute numbers of total cells (r = 0.779, P < .001), lymphocytes (r = 0.842, P < .001), neutrophils (r = 0.809, P < .001), and eosinophils (r = 0.621, P = .010) but did not correlate with macrophages. Normalization to albumin indicated that BAFF production occurred locally in the airways. BAFF levels were also significantly correlated with the other B cell-activating cytokines IL-6 (r = 0.875, P < .001) and IL-13 (r = 0.812, P < .001). The antigen-induced production of BAFF in the airway might contribute to local class-switch recombination and immunoglobulin synthesis by B cells.

The endogenous danger signal, crystalline uric acid, signals for enhanced antibody immunity

AbstractStudies have shown that the immune system can recognize self-antigens under conditions (eg, cell injury) in which the self-tissue might elaborate immune-activating endogenous danger signals. Uric acid (UA) is an endogenous danger signal recently identified to be released from dying cells. Prior work has shown that UA activates immune effectors of both the innate and adaptive immune system, including neutrophils and cytotoxic T-cell immunity. However, it was unclear whether UA could enhance antibody immunity, which was examined in this study. When added to dying tumor cells or with whole protein antigen, UA increased IgG1-based humoral immunity. Further, UA blocked growth of tumor in subsequent tumor challenge experiments, which depended on CD4, but not CD8, T cells. Sera derived from UA-treated animals enhanced tumor growth, suggesting it had little role in the antitumor response. UA did not signal for T-cell expansion or altered tumor-infiltrating leukocyte populations. Consistent with the lack of T-cell expansion, when applied to dendritic cells, UA suppressed T-cell growth factors but up-regulated B cell–activating cytokines. Understanding the nature of endogenous danger signals released from dying cells may aid in a better understanding of mechanisms of immune recognition of self.

Pre-Clinical Activity of a Novel FcγRIIIa Engineered CD19 Monoclonal Antibody in B Cell Chronic Lymphocytic Leukemia and Acute Lymphoblastic Leukemia.

CD19 is a B cell lineage-specific transmembrane signaling protein that controls differentiation and proliferation. CD19 is an attractive therapeutic target due to its high level of expression in numerous B cell malignancies, as well as its lack of expression on non-B cells. Here we report the in vitro anti-tumor activity of a novel humanized monoclonal anti-CD19 Ab (CD19-IgG1, aka XENP5603) and its Fc engineered counterpart (XmAb™CD19, aka XENP5574). XENP5603 induced direct apoptosis in normal CD19+ B cells, but not NK cells, T cells, or monocytes, as determined by flow cytometric staining with annexin V and propidium iodide. XENP5603 also induced significant levels of apoptosis in a number of lymphoblastoid cell lines, including Ramos, Raji, 697, NALM6, and RS4;11 cells. Treatment of primary chronic lymphocytic leukemia (CLL) cells with XENP5603 induced significant cell death in all patients tested (mean, 36% apoptotic cells at 24 hours; range, 13–66%, p < 0.001). Similar apoptosis was noted in cells from a subset of patients (4 of 9) with CD19+ primary acute lymphoblastic leukemia (ALL). Apoptosis of CLL cells treated with XENP5603 was not associated with cleavage of caspase-3, caspase-8, caspase-9, or PARP, but was associated with upregulation of Bim, suggesting a caspase-independent mechanism of cell death. NK cells from normal donors exhibited high levels of ADCC in response to B cell lines coated with XENP5603. Furthermore, NK cells from CLL patients mediated significant ADCC against autologous CLL cells in the presence of XENP5603 (mean, 15% specific lysis at an E:T ratio of 25:1; range, 8–24%; p = 0.04 vs. the negative control Ab). ADCC activity was further increased in the presence of XENP5574, which has the same antigen-recognition sequences as XENP5603 but which contains two mutations in the Fc region that increase FcγRIIIa affinity (mean, 39% specific lysis at an E:T ratio of 25:1; range, 29–51%; p = 0.02 vs. the negative control Ab). ADCC mediated by either CD19 Ab was also significantly higher than that mediated by an equivalent concentration of rituximab (mean, 39% specific lysis with XENP5574 vs. 12% with rituximab; p < 0.001). ADCC in the presence of either Ab was further increased in the presence of the NK cell-activating cytokine IL-2, suggesting that these antibodies might be effectively combined with immune stimulatory adjuvants. Furthermore, NK cell ADCC against CLL cells in the presence of CD19 Abs was found to be dependent on perforin/granzyme release, as treatment with 3,4-dichloroisocoumarin (which inhibits granzyme enzymatic activity) or EGTA (which prevents release of cytotoxic vesicles) potently inhibited ADCC activity. Collectively, these studies provide evidence of the autologous innate immune-mediated cytotoxicity and direct apoptotic activity of XENP5603 and XENP5574. In addition, engineering to enhance FcγRIIIa binding enhances autologous ADCC, providing support for further pre-clinical development of XENP5574 in CD19+ malignancies, including CLL and ALL.

Lenalidomide and pomalidomide strongly enhance tumor cell killing in vitro during antibody-dependent cellular cytotoxicity (ADCC) mediated by trastuzumab, cetuximab and rituximab

3023 Background: Potential mechanisms of action of lenalidomide and pomalidomide (CC-4047) include anti-angiogenic, anti- proliferative and immunomodulatory activities, e.g., enhancement of T cell and NK cell function. Both drugs appear to enhance T cell activation and Th1-type cytokines in cancer patients. Also, both drugs have been shown to enhance rituximab-mediated protection in a mouse lymphoma model. Methods: We have utilized an in vitro ADCC system to assess the ability of these drugs to enhance human NK cell function in response to the approved therapeutic antibodies trastuzumab, cetuximab and rituximab. Results: Pre-treatment of NK cells with either pomalidomide or lenalidomide greatly enhanced IFN-γ production by NK cells in response to IgG in the presence of either IL-2 or IL- 12. In a series of functional ADCC assays, Her2/neu overexpressing breast cancer cells (SKBR3 &amp; MCF-7) pre-coated with trastuzumab, EGFR positive colorectal cancer cells (HCT-116) pre-coated with cetuximab and NHL cell lines (Namalwa, Farage &amp; Raji) pre-coated with rituximab, were exposed to NK cells pre-treated with pomalidomide, lenalidomide or thalidomide. Both pomalidomide and lenalidomide synergistically increased (up to 6-fold) NK cell-mediated killing of antibody coated tumor cells in a dose-dependent manner. Thalidomide had no effect in this system. There was minimal tumor cell killing by antibody alone or in the absence of antibody. The presence of IL-2 or IL-12 was required to see enhanced killing by either drug. Enhanced ADCC was associated with increased signaling in NK cells, specifically with inhibition of the negative regulator SHIP-1. Other downstream effects on signaling pathways are also being investigated. Monocyte-mediated tumor cell ADCC was also enhanced by both drugs. Conclusions: We have shown that pomalidomide and lenalidomide (but not thalidomide) strongly enhance the ability of therapeutic antibodies to induce ADCC via NK cell/monocyte-mediated killing of tumor cells in vitro. These results provide a strong rationale for combination of either lenalidomide or pomalidomide with antibodies to tumor-specific surface antigens in cancer patients. No significant financial relationships to disclose.

A distinct role for PI3Kgamma in suppressing the development and progression of experimental autoimmune encephalomyelitis (EAE) (129.30)

Abstract Phosphoinositide 3-kinases (PI3K) are intracellular signaling proteins involved in cellular responses such as chemotaxis, proliferation and apoptosis. Selective inhibitors of the PI3Kγ-isoform have recently become available. This study explores the role of PI3Kγ in the development and progression of EAE. PI3Kγ +/+ (wt) and PI3Kγ −/− (ko) mice were immunized for EAE using myelin oligodendrocyte glycoprotein p35-55 (MOG) and assessed for clinical signs, CNS histopathology and T cell activation. WT mice showed a progressive disease course with elevations in inflammatory cytokines increased CNS mononuclear infiltrates. In contrast, ko mice exhibited a delayed onset and dramatically less severe EAE course characterized by decreased T cell activation and inflammatory cytokines (TNF-α, IFN-γ, IL-2, IL-12p40, IL-6, IL-17 and MCP-1). Male ko mice were significantly more protected than ko females. Adoptive transfer of MOG-activated T cells into ko recipients show that ko mice are resistant to passive disease induction. Interestingly, wt recipients of ko donors immunized for EAE were also protected. Furthermore, adoptive transfer of activated GFP+ T cells show marked decreased infiltration of GFP+ T cells into the CNS. Taken together, these findingssuggest that depletion of PI3Kγ results in a down-regulation of the inflammatoryresponse caused by impaired trafficking of cells critical to generation of the immune response. (Supported by NIH grant AI 064320 and National MS Society Grant RG 3272).

Monocyte cytokine and costimulatory molecule expression in patients infected with Leishmania mexicana

Leishmania mexicana causes localized and diffuse cutaneous leishmaniasis. Patients with localized cutaneous leishmaniasis (LCL) develop a benign disease, whereas patients with diffuse cutaneous leishmaniasis (DCL) suffer from a progressive disease associated with anergy of the cellular response towards Leishmania antigens. We evaluated the production of the interleukins (IL) IL-12, IL-15, IL-18 and tumour necrosis factor-alpha (TNF-alpha) and the expression of the costimulatory molecules CD40, B7-1 and B7-2 in monocytes from LCL and DCL patients, stimulated in vitro with Leishmania mexicana lipophosphoglycan (LPG) for 18 h. LCL monocytes significantly increased TNF-alpha, IL-15 and IL-18 production, and this increase was associated with reduced amounts of IL-12. DCL monocytes produced no IL-15 or IL-18 and showed a decreasing tendency of TNF-alpha and IL-12 production as the severity of the disease increased. No difference was observed in the expression of CD40 and B7-1 between both groups of patients, yet B7-2 expression was significantly augmented in DCL patients. It remains to be established if this elevated B7-2 expression in DCL patients is cause or consequence of the Th2-type immune response that characterizes these patients. These data suggest that the diminished ability of the monocytes from DCL patients to produce cell-activating innate proinflammatory cytokines when stimulated with LPG is a possible cause for disease progression.

Valsartan improves resting skin blood flow in type 2 diabetic patients and reduces poly(adenosine diphosphate-ribose) polymerase activation

To examine the effect of a 12-week daily treatment with 160 mg of valsartan, an angiotensin II receptor blocker, on the microcirculation and macrocirculation of type 2 diabetic patients (T2DM) and healthy subjects. This was a prospective, randomized, double-blind, placebo-controlled crossover study. Thirteen T2DM with no severe complications and 13 healthy subjects completed the trial. Treatment with valsartan in T2DM improved the resting forearm skin blood flow and increased the resting brachial artery diameter but had no effects on arterial blood pressure, large vessel vascular reactivity, or carotid intima-media thickness. Resting skin blood flow increased by 60% (2%-90%; median and 25th-75th percentiles) during valsartan treatment and by only 2% (-22% to 27%) during placebo treatment (P < .05). No changes were observed in the nondiabetic subjects. Immunostaining studies of forearm skin biopsy samples from T2DM and healthy subjects showed that valsartan reduced poly(adenosine diphosphate-ribose) polymerase (PARP) activity in 50% (6/12) of the subjects. PARP activity remained unchanged in placebo-treated subjects (P < .02). In addition, valsartan treatment increased CD31 staining in 33% (4/12) of the subjects, whereas no change was noted in sequential skin biopsy samples of placebo-treated subjects (P = .057). Valsartan had no effect on the biochemical markers of endothelial cell activation and other cytokines, including CAMs, interleukin 6, tumor necrosis factor alpha, C-reactive protein, adiponectin, and plasma activator inhibitor 1. Valsartan increases the resting skin blood flow in T2DM, likely through reduction of PARP activity.

Regulation of T Cell Homeostasis and Cell Cycling in Patients with Acute Myeloid Leukemia.

Background and Aims: Although leukemic cells express tumor-associated antigens, suppression of an effective T cell immune response is a well known phenomenon in acute myeloid leukemia (AML). In principle, the malignant cells may escape immune surveillance by (1) incomplete T cell activation due to the absence of costimulatory molecules on the leukemic cell types, (2) secretion of soluble immunosuppressive factors, which may lead among others to (3) induction of anergic and/or regulatory T cell phenotypes. A better understanding of the underlying mechanism would have important implications for the development of immunotherapeutic strategies.Methods: CD3+ T cells were analyzed for activation, proliferation and Th1 cytokine production after coculturing with primary AML cells or leukemic cell supernatant. In addition, self-developed human Treg microarrays were used to reveal a gene expression profile of CD4+ T cells isolated from untreated AML patients (n=7) in comparison to CD4+ T cells from healthy volunteers (n=6) and AML patients after achieving a complete remission (n=4). The specific regulation of selected canditate genes was confirmed by realtime RT-PCR. Based on microarray results cell-cycle analyses were performed in order to study the effect of primary AML cells on the cell-cycle progression of stimulated T-cells.Results: Our studies could show that primary AML cells suppress T cell activation, proliferation and Th1 cytokines production mainly in a cell-contact dependent manner and to a minor degree via soluble factors. Nevertheless, cell-cycle analyses demonstrated that soluble factors from leukemic cell supernatants may inhibit the cell-cycle entry of T cells after mitogenic stimulation with an arrest in G0/G1 phase. Interestingly, the molecular profile of CD4+ T cells isolated from untreated AML patients could identify a profound dysregulation of molecules involved in the regulation of cell-cycle (i.e., CDK4, Vav2, Egr-1, Id2) and apoptosis (i.e., Bcl-2, Bax). In addition, genes important for the immune response (i.e., IL2R, CTLA-4), especially various chemokines/-receptors (i.e., RANTES, CXCL10, CCR2) were dysregulated, whereas the expression pattern of genes specific for regulatory T cells (i.e., FoxP3, PD-1, GITR) were broadly unaffected.Conclusion: AML cells (in-)/directly modulate normal T cell function such as activation, proliferation, cytokine/chemokine production and cell-cycle regulation. One might speculate that the lack of an effective anti-tumor response is associated with a cell-cycle arrest resulting in T cell anergy. Cell-cycle regulators may serve as potential targets for novel immunotherapeutic strategies to eradicate minimal residual disease in patients with AML.

Sequential activation of NKT cells and NK cells provides effective innate immunotherapy of cancer

The CD1d reactive glycolipid, α-galactosylceramide (α-GalCer), potently activates T cell receptor-α type I invariant NKT cells that secondarily stimulate the proliferation and activation of other leukocytes, including NK cells. Here we report a rational approach to improving the antitumor activity of α-GalCer by using delayed interleukin (IL)-21 treatment to mature the α-GalCer–expanded pool of NK cells into highly cytotoxic effector cells. In a series of experimental and spontaneous metastases models in mice, we demonstrate far superior antitumor activity of the α-GalCer/IL-21 combination above either agent alone. Superior antitumor activity was critically dependent upon the increased perforin-mediated cytolytic activity of NK cells. Transfer of α-GalCer–pulsed dendritic cells (DCs) followed by systemic IL-21 caused an even more significant reduction in established (day 8) metastatic burden and prolonged survival. In addition, this combination prevented chemical carcinogenesis more effectively. Combinations of IL-21 with other NK cell–activating cytokines, such as IL-2 and IL-12, were much less effective in the same experimental metastases models, and these cytokines did not substitute effectively for IL-21 in combination with α-GalCer. Overall, the data suggest that NK cell antitumor function can be enhanced greatly by strategies that are designed to expand and differentiate NK cells via DC activation of NKT cells.

Cytokine changes in the horizontal diagonal band of broca in the septum after running and stroke: A correlation to glial activation

The relationship between running, glial cell activation and pro-inflammatory cytokines was studied in the context of neuroprotection against ischemic stroke induced by middle cerebral artery occlusion (MCAO). This was investigated in four groups of rats, namely, (1) nonrunner, (2) runner after 12 weeks of treadmill running, (3) nonrunner with MCAO and (4) runner with MCAO. The horizontal diagonal band of Broca (HDB) in the septum was scrutinized for qualitative cum quantitative changes in the microglia and astrocytes. Reverse transcription–polymerase chain reactionand immunoblot work were carried out in the forebrain homogenate to determine, respectively, the gene and protein expression of several pro-inflammatory cytokines. Our results indicated that the runner exhibited less immunoreactivity and reduced numbers of glial cells within the HDB compared with the nonrunner. Interestingly, the mRNA and protein levels of tumor necrosis factor-α, interleukin (IL)-1β, IL-6 and interferon-γ, were significantly downregulated in the runner. Our data also suggest albeit with some inconsistency that the runner/MCAO rats had benefited from running. These observations suggest that running can result in changes to the microenvironment, in which the microglia and astrocytes exist in a state of quiescence concomitant with a reduced expression of pro-inflammatory cytokines, that may lead to beneficial effects seen in ischemic stroke induced by MCAO.

CD4+CD25- effector T cells from healthy controls and MS patients do not differ in mRNA expression of IFN-γ, IL-2, and TNF-α

Relapsing remitting multiple sclerosis (RRMS) is supposed to be an inflammatory, demyelininating T cell mediated autoimmune disease of the central nervous system (CNS). A prerequisite for the induction of autoimmunity within the CNS is the priming and activation of self-reactive T cell clones in the periphery (blood, secondary lymphatic organs). One target for T cell activation within the T cell pool are resting, unactivated CD4+ T helper cells. Therefore we analyzed freshly isolated peripheral blood CD4+CD25- T effector cells (Teff) for mRNA expression profiles of T cell activation cytokines interferon gamma (IFN-γ), interleukin 2 (IL-2) and tumor necrosis factor alpha (TNF-α).