bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of Eosinophilopoiesis in a Murine Model of Asthma
Authors: Hogan Mary Beth , Weissman David N. , Hubbs Ann F. , Gibson Laura F. , Piktel Debra , Landreth Kenneth S.
Published: April 2014

Eosinophilic inflammation plays a key role in tissue damage that characterizes asthma. Eosinophils are produced in bone marrow and recent observations in both mice and humans suggest that allergen exposure results in increased output of eosinophils from hemopoietic tissue in individuals with asthma. However, specific mechanisms that alter eosinophilopoiesis in this disease are poorly understood. The current study used a well-characterized murine animal model of asthma to evaluate alterations of eosinophil and eosinophil progenitor cells (CFU-eo) in mice during initial sensitization to allergen and to determine whether observed changes in either cell population were regulated by T lymphocytes. Following the first intranasal installation of OVA, we observed sequential temporal elevation of eosinophils in bone marrow, blood, and lung. In immunocompetent BALB/c mice, elevation of bone marrow eosinophils was accompanied by transient depletion of CFU-eo in that tissue. CFU-eo rebounded to elevated numbers before returning to normal baseline values following intranasal OVA exposure. In T cell-deficient BALB/c nude (BALB/cnu/nu) mice, CFU-eo were markedly elevated following allergen sensitization, in the absence of bone marrow or peripheral blood eosinophilia. These data suggest that eosinophilia of asthma results from alterations in two distinct hemopoietic regulatory mechanisms. Elevation of eosinophil progenitor cells in the bone marrow is T cell independent and likely results from altered bone marrow stromal cell function. Differentiation of eosinophil progenitor cells and phenotypic eosinophilia is T cell dependent and does not occur in athymic nude mice exposed to intranasal allergen.
Therapeutic Attenuation of Pulmonary Fibrosis Via Targeting of IL-4- and IL-13-Responsive Cells
Authors: Jakubzick Claudia , Choi Esther S. , Joshi Bharat H. , Keane Michael P. , Kunkel Steven L. , Puri Raj K. , Hogaboam Cory M.
Published: April 2014

Severe forms of idiopathic interstitial pneumonia (IIP), such as usual interstitial pneumonia, can be impervious to modern steroid and immunosuppressive treatment regimens, thereby emphasizing the need for novel effective therapies. Consequently, research attention has been directed toward understanding the cytokine networks that may affect fibroblast activation and, hence, the progression of certain IIPs. This led us to investigate whether the specific targeting of resident lung cells responsive to IL-4 and IL-13 exerted a therapeutic effect in an experimental model of IIP, namely the bleomycin-induced model of pulmonary fibrosis. IL-4, IL-13, and their corresponding receptor subunits, IL-4Rα, IL-13Rα1, and IL-13Rα2, were maximally expressed at the mRNA and protein levels in whole lung samples on day 21 or 28 after an intratracheal bleomycin challenge. The intranasal administration of an IL-13 immunotoxin chimeric molecule (IL13-PE) from days 21–28, but not for 1-wk periods at earlier times, after bleomycin challenge had a significant therapeutic effect on histological and biochemical parameters of bleomycin-induced pulmonary fibrosis compared with the control group. The intranasal IL13-PE therapy significantly reduced the numbers of IL-4 and IL-13 receptor-positive mononuclear cells and macrophages and the levels of profibrotic cytokine and chemokine in the lungs of bleomycin-challenged mice on day 28. Thus, this study demonstrates that IL-4- and/or IL-13-binding cells are required for the maintenance of pulmonary fibrosis induced by bleomycin and highlights the importance of further investigation of antifibrotic therapeutics that target these cells during pulmonary fibrosis.
Activation of Cutaneous Protein Kinase Cα Induces Keratinocyte Apoptosis and Intraepidermal Inflammation by Independent Signaling Pathways
Authors: Cataisson Christophe , Joseloff Elizabeth , Murillas Rodolfo , Wang Alice , Atwell Coralyn , Torgerson Sara , Gerdes Michael , Subleski Jeffrey , Gao Ji-Liang , Murphy Philip M. , Wiltrout Robert H. , Vinson Charles , Yuspa Stuart H.
Published: April 2014

Skin keratinocytes are major mediators of host immune responses. The skin is also a target for immunologically based inflammation in many pathological states. Activation of protein kinase C (PKC) can induce cutaneous inflammation, but the precise role of each of six cutaneous PKC isoforms (α, δ, ε, η, ζ, μ) that regulate normal skin homeostasis or contribute to skin pathology has not been clarified. We generated transgenic mice that overexpress PKCα in the basal layer of the epidermis and the outer root sheath of hair follicles under the regulation of the bovine keratin 5 promoter. K5-PKCα transgenic mice exhibit severe intraepidermal neutrophilic inflammation and disruption of the epidermis and upper hair follicles when treated topically with 12-O-tetradecanoylphorbol-13-acetate (TPA). Both TPA and UVB cause apoptosis in transgenic skin, but only TPA evokes intraepidermal inflammation. TPA also induces apoptosis in cultured transgenic keratinocytes, and this is prevented by an AP-1 dominant-negative construct. However, inhibiting AP-1 in vivo does not abrogate intraepidermal inflammation. Transcripts for specific cytokines and chemokines are elevated in TPA-treated cultured transgenic keratinocytes, and conditioned culture medium from these cells promotes neutrophil migration in vitro. Chemokine expression and neutrophil migration are not diminished by inhibiting AP-1. Thus, PKCα activation induces keratinocyte apoptosis via an AP-1-dependent pathway and mediates chemokine induction and intraepidermal inflammation independently. This model system will be useful to define specific chemokines regulated by PKCα that promote intraepidermal neutrophilic inflammation, a condition that characterizes several human cutaneous diseases such as pustular psoriasis and acute generalized exanthematous pustulosis.
Electroporation Enables Plasmid Vaccines to Elicit CD8+ T Cell Responses in the Absence of CD4+ T Cells
Authors: Dayball Kelley , Millar James , Miller Mark , Wan Yong Hong , Bramson Jonathan
Published: April 2014

In vivo electroporation dramatically enhances plasmid vaccine efficacy. This enhancement can be attributed to increased plasmid delivery and, possibly, to some undefined adjuvant properties. Previous reports have demonstrated CD8+ T cell priming by plasmid vaccines is strongly dependent upon CD4+ T cell help. Indeed, the efficacy of a plasmid vaccine expressing Escherichia coli β-galactosidase was severely attenuated in MHC class II-deficient (C2D) mice. To determine whether electroporation could compensate for the absence of CD4+ T cell help, C2D mice were immunized by a single administration of plasmid in combination with electroporation using two conditions which differed only by the duration of the pulse (20 or 50 msec). Both conditions elicited robust cellular and humoral responses in wild-type mice, as measured by IFN-γ ELISPOT, anti-β-galactosidase ELISA, and protection from virus challenge. In C2D mice, the cellular response produced by the vaccine combined with the 50-msec pulse, as measured by ELISPOT, was identical to the response in wild-type mice. The 20-msec pulse elicited a milder response that was approximately one-fifth that of the response elicited by the 50-msec pulse. By contrast, the 20-msec conditions provided comparable protection in both wild-type and C2D recipients whereas the protection elicited by the 50-msec conditions in C2D mice was weaker than in wild-type mice. Further investigation is required to understand the discordance between the ELISPOT results and outcome of virus challenge in the C2D mice. Nonetheless, using this technique to prime CD8+ T cells using plasmid vaccines may prove extremely useful when immunizing hosts with limiting CD4+ T cell function, such as AIDS patients.
In Vivo Treatment of Class II MHC-Deficient Mice with Anti-TCR Antibody Restores the Generation of Circulating CD4 T Cells and Optimal Architecture of Thymic Medulla
Authors: Nasreen Mariam , Ueno Tomoo , Saito Fumi , Takahama Yousuke
Published: April 2014

TCR ligation by the self-peptide-associated MHC molecules is essential for T cell development in the thymus, so that class II MHC-deficient mice do not generate CD4+CD8− T cells. The present results show that the administration of anti-TCR mAb into class II MHC-deficient mice restores the generation of CD4+CD8− T cells in vivo. The CD4 T cells were recovered in the thymus, peripheral blood, and the spleen, indicating that the anti-TCR treatment is sufficient for peripheral supply of newly generated CD4 T cells. Unlike peripheral CD4 T cells that disappeared within 5 wk after the treatment, CD4+CD8− thymocytes remained undiminished even after 5 wk, suggesting that CD4 T cells in the thymus are maintained separately from circulating CD4 T cells and even without class II MHC molecules. It was also found that the mass of medullary region in the thymus, which was reduced in class II MHC-deficient mice, was restored by the anti-TCR administration, suggesting that the medulla for CD4+CD8− thymocytes is formed independently of the medulla for CD4−CD8+ thymocytes. These results indicate that in vivo anti-TCR treatment in class II MHC-deficient mice restores the generation of circulating CD4 T cells and optimal formation of the medulla in the thymus, suggesting that anti-TCR Ab may be useful for clinical treatment of class II MHC deficiencies.
Death Decoy Receptor TR6/DcR3 Inhibits T Cell Chemotaxis In Vitro and In Vivo
Authors: Shi Guixiu , Wu Yulian , Zhang Jun , Wu Jiangping
Published: April 2014

TR6/DcR3 is a secreted molecule belonging to the TNFR family. Its ligands are LIGHT, Fas ligand, and TL1A, all TNF family members. TR6 is expressed in some tumors and is hypothesized to endow tumor cells with survival advantages by blocking Fas-mediated apoptosis. It can also inhibit T cell activation by interfering with two-way T cell costimulation between LIGHT and HveA. In this study, we discovered a novel function of TR6: inhibition of T cell chemotaxis. Human T cells pretreated with soluble or solid-phase TR6-Fc showed compromised migration toward CXCL12/stromal cell-derived factor 1α in vitro in a Transwell assay. Such an effect could also be observed in T cells pretreated with soluble or solid-phase HveA-Fc or anti-LIGHT mAb, suggesting that LIGHT reverse signaling was likely responsible for chemotaxis inhibition. TR6 pretreatment also led to T cell chemotaxis suppression in vivo in the mice, confirming in vivo relevance of the in vitro observation. Mechanistically, a small GTPase Cdc42 failed to be activated after TR6 pretreatment of human T cells, and further downstream, p38 mitogen-activated protein kinase activation, actin polymerization, and pseudopodium formation were all down-regulated in the treated T cells. This study revealed a previously unknown function of TR6 in immune regulation, and such an effect could conceivably be explored for therapeutic use in controlling undesirable immune responses.
Human Tumor-Derived Heat Shock Protein 96 Mediates In Vitro Activation and In Vivo Expansion of Melanoma- and Colon Carcinoma-Specific T Cells
Authors: Rivoltini Licia , Castelli Chiara , Carrabba Matteo , Mazzaferro Vincenzo , Pilla Lorenzo , Huber Veronica , Coppa Jorgelina , Gallino Gianfrancesco , Scheibenbogen Carmen , Squarcina Paola , Cova Agata , Camerini Roberto , Lewis Jonathan J. , Srivastava Pramod K. , Parmiani Giorgio
Published: April 2014

Heat shock proteins (hsp) 96 play an essential role in protein metabolism and exert stimulatory activities on innate and adaptive immunity. Vaccination with tumor-derived hsp96 induces CD8+ T cell-mediated tumor regressions in different animal models. In this study, we show that hsp96 purified from human melanoma or colon carcinoma activate tumor- and Ag-specific T cells in vitro and expand them in vivo. HLA-A*0201-restricted CD8+ T cells recognizing Ags expressed in human melanoma (melanoma Ag recognized by T cell-1 (MART-1)/melanoma Ag A (Melan-A)) or colon carcinoma (carcinoembryonic Ag (CEA)/epithelial cell adhesion molecule (EpCAM)) were triggered to release IFN-γ and to mediate cytotoxic activity by HLA-A*0201-matched APCs pulsed with hsp96 purified from tumor cells expressing the relevant Ag. Such activation occurred in class I HLA-restricted fashion and appeared to be significantly higher than that achieved by direct peptide loading. Immunization with autologous tumor-derived hsp96 induced a significant increase in the recognition of MART-1/Melan-A27–35 in three of five HLA-A*0201 melanoma patients, and of CEA571–579 and EpCAM263–271 in two of five HLA-A*0201 colon carcinoma patients, respectively, as detected by ELISPOT and HLA/tetramer staining. These increments in Ag-specific T cell responses were associated with a favorable disease course after hsp96 vaccination. Altogether, these data provide evidence that hsp96 derived from human tumors can present antigenic peptides to CD8+ T cells and activate them both in vitro and in vivo, thus representing an important tool for vaccination in cancer patients.
Genetic Reprogramming of Primary Human T Cells Reveals Functional Plasticity in Th Cell Differentiation
Authors: Sundrud Mark S. , Grill Stacy M. , Ni Donghui , Nagata Kinya , Alkan Sefik S. , Subramaniam Arun , Unutmaz Derya
Published: April 2014

Activation of naive T cells through the TCR and cytokine signals directs their differentiation into effector or memory subsets with different cytokine profiles. Here, we tested the flexibility of human Th1 or Th2 differentiation by forced expression of transcription factors T-bet and GATA-3. Ectopic expression of T-bet and GATA-3 in freshly isolated human TN cells resulted in their differentiation to a Th1 and Th2 phenotype, respectively, in the absence of polarizing cytokines. Introduction of GATA-3 into lineage-committed Th1 cells induced the expression of Th2-specific cytokines (IL-4 and IL-5) and chemotactic receptors (CCR4, chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2). However, these cells partially maintained their Th1-specific profile (IFN-γ and IL-12Rβ2 expression). Conversely, expression of T-bet in lineage-committed Th2 cells caused a more profound switch to the Th1 phenotype, including the up-regulation of CXCR3 and down-regulation of CCR4 and CRTH2. Interestingly, similar to the naive T cell subset, central memory T cells were also largely programmed toward Th1 or Th2 effector cells upon expression of T-bet and GATA-3, respectively. However, expression of these transcription factors in effector memory T cells was much less influential on cytokine and chemokine receptor expression profiles. Our results reveal remarkable plasticity in the differentiation programs of human memory T cells. This flexibility is progressively diminished as cells mature from naive to effector T cells. These findings have important implications in understanding the molecular mechanisms of human T cell differentiation and for devising novel therapeutic strategies aimed at immunomodulation of skewed effector T cell responses.
Induction of Macrophage Insulin-Like Growth Factor-I Expression by the Th2 Cytokines IL-4 and IL-13
Authors: Wynes Murry W. , Riches David W. H.
Published: April 2014

Macrophage-derived insulin-like growth factor-I (IGF-I) has long been implicated in the pathogenesis of the interstitial lung disease, idiopathic pulmonary fibrosis, in part, by its ability to 1) stimulate the proliferation and survival of fibroblasts and myofibroblasts and 2) promote collagen matrix synthesis by these cells. However, little is known about the mechanisms that stimulate the expression of IGF-I by macrophages. Previous studies have shown that the development of pulmonary fibrosis is accompanied by enhanced expression of Th2-profile cytokines, especially IL-4, and diminished expression of Th1 cytokines, including IFN-γ. In addition, in vitro studies have shown that IFN-γ down-regulates the expression of IGF-I. Thus, the paucity of IFN-γ in the fibrotic lung may favor increased growth factor production by allowing Th2 cytokines to predominate. In view of these findings, we investigated the hypothesis that Th2 cytokines stimulate the expression of IGF-I by macrophages. Incubation with IL-4 or IL-13 led to concentration- and time-dependent increases in the expression of IGF-I mRNA and the secretion of IGF-I protein by mouse macrophages as a consequence of increased transcription of IGF-I pre-mRNA. Exposure of macrophages to IL-4 in the presence of IFN-γ inhibited the increase in the expression of IGF-I. Studies using STAT6-deficient macrophages indicated that the increase in IGF-I expression was dependent on STAT6. In addition, the down-regulation of IGF-I expression by IFN-γ was absent in STAT1-deficient macrophages. Collectively, these findings define a homeostatic mechanism in which Th2 cytokines promote, and Th1 cytokines inhibit, the expression of IGF-I by macrophages.
CC Chemokine Ligand 2 and Its Receptor Regulate Mucosal Production of IL-12 and TGF-β in High Dose Oral Tolerance
Authors: DePaolo R. William , Rollins Barrett J. , Kuziel William , Karpus William J.
Published: April 2014

Oral tolerance is the result of a complex immunoregulatory strategy used by the gut and its associated lymphoid tissues to render the peripheral immune system unresponsive to nonpathogenic proteins, such as food or commensal bacteria. The mechanism of oral tolerance induction and maintenance is not well understood. We have previously shown that the chemokine, CC chemokine ligand 2 (CCL2), is important for the induction and maintenance of oral tolerance. To address the role CCL2 plays in oral tolerance, we used both CCL2−/− and CCR2−/− mice. Cells from the spleen, mesenteric lymph nodes, and peripheral lymph nodes of CCL2−/− and CCR2−/− mice fed high doses of OVA showed robust proliferative responses compared with cells from Ag-fed wild-type mice. CCL2−/− and CCR2−/− mice also produced high amounts of Th1 cytokines such as IL-2 and IFN-γ and very low amounts of IL-4 and IL-10. The ability of APCs from the gut of CCL2−/− and CCR2−/− OVA-fed mice to stimulate an indicator T cell line was evaluated. APCs from the Peyer’s patch of OVA-fed knockout animals could induce a T cell response measured by an increase in proliferation and generation of IL-12 and IFN-γ with a concomitant reduction of TGF-β compared with wild-type controls that did not induce a Th1 response. These data indicate that CCL2 and signaling through its receptor CCR2 is critical for the induction of oral tolerance by regulating Ag presentation leading to a disruption in the balance of inflammatory and regulatory cytokines.
Cellular Events Involved in Butyric Acid-Induced T Cell Apoptosis
Authors: Kurita-Ochiai Tomoko , Amano Shigeru , Fukushima Kazuo , Ochiai Kuniyasu
Published: April 2014

We have previously demonstrated that butyric acid induces cytotoxicity and apoptosis of murine thymocytes, splenic T cells, and human Jurkat T cells. Therefore, to determine the apoptotic signaling pathway induced by butyric acid, we investigated the contribution of reactive oxygen species (ROS), mitochondria, ceramide, and mitogen-activated protein kinases in butyric acid-induced human Jurkat cell apoptosis. After exposure of cells to butyric acid, a pronounced accumulation of ROS was seen. Pretreatment of cells with the antioxidant N-acetyl-cysteine or 3-aminobenzamide attenuated butyric acid-induced apoptosis through a reduction of ROS generation. Cytochrome c, apoptosis-inducing factor, and second mitochondria-derived activator of caspases protein release from mitochondria into the cytosol were detected shortly after butyric acid treatment. Exposure of cells to butyric acid resulted in an increase in cellular ceramide in a time-dependent fashion. In addition, butyric acid-induced apoptosis was inhibited by DL-threo-dihidrosphingosine, a potent inhibitor of sphingosine kinase. Using anti-extracellular signal-regulated kinase (ERK), anti-c-Jun N-terminal kinase (JNK), and anti-p38 phosphospecific Abs, we showed a decrease in ERK, but not in JNK and p38 phosphorylation after treatment of cells with butyric acid. Pretreatment of cells with the JNK inhibitor SP600125 attenuated the effect of butyric acid on apoptosis, whereas no effect was seen with the p38 inhibitor SB202190 or the ERK inhibitor PD98059. Taken together, our results indicate that butyric acid-induced T cell apoptosis is mediated by ceramide production, ROS synthesis in mitochondria, and JNK activation in the mitogen-activated protein kinase cascade. Finally, these results were further substantiated by the expression profile of butyric acid-treated Jurkat cells obtained by means of cDNA array.
Exogenous Administration of Gangliosides Inhibits FcεRI-Mediated Mast Cell Degranulation by Decreasing the Activity of Phospholipase Cγ
Authors: Dráberová Lubica , Dudková Lenka , Boubelík Michael , Tolarová Helena , Šmíd František , Dráber Petr
Published: April 2014

Gangliosides released from tumor cells, as well as administered exogenously, suppress the immune responses by largely unknown mechanisms. We show here that a pretreatment of rat basophilic leukemia cells with isolated brain gangliosides inhibited the release of preformed secretory mediators from cells activated via FcεRI but not Thy-1 glycoprotein. Exogenously administered gangliosides also affected the cell-substrate adhesion and the levels of polymeric filamentous actin in Ag-activated cells. Although the production of phosphoinositides was also decreased, enzymatic activity of phosphatidylinositol 3-kinase was not inhibited. Gangliosides had no or only marginal effect on the association of aggregated FcεRI with glycosphingolipid-enriched membranes and on tyrosine phosphorylation of FcεRI and the linker for activation of T cells. Though pretreatment with gangliosides did not inhibit the association of linker for activation of T cells with phospholipase C (PLC)γ1 and PLCγ2, tyrosine phosphorylation of these enzymes, as well as their enzymatic activities and association with detergent-insoluble signaling assemblies were reduced. This resulted in a decreased production of inositol 1,4,5-trisphosphate and an inhibition of Ca2+ mobilization. The combined data support the concept that exogenously administered gangliosides interfere with those properties of glycosphingolipid-enriched membranes that are important for the formation of plasma membrane-associated signaling assemblies containing PLCγ but not for initial tyrosine phosphorylation of FcεRI subunits.
Substance P Regulates Th1-Type Colitis in IL-10 Knockout Mice
Authors: Weinstock Joel V. , Blum Arthur , Metwali Ahmed , Elliott David , Bunnett Nigel , Arsenescu Razvan
Published: April 2014

Substance P (SP) is a proinflammatory molecule that interacts with a neurokinin 1 receptor (NK-1R), which is on T cells and helps control IFN-γ production. IL-10−/− mice given a nonsteroidal anti-inflammatory drug (NSAID) develop Th1 colitis. We studied the importance of SP and NK-1R in this colitis model. LP T cells were isolated to study their NK-1R expression. LP T cells from IL-10−/− mice expressed NK-1R and produced IFN-γ only after NSAID treatment and induction of colitis. LP T cells from NSAID-treated wild-type controls or from age-matched untreated IL-10−/− animals did not express NK-1R or produce IFN-γ. Experiments showed that IL-12 induced NK-1R transcription in CD4+ T cells cultured in vitro. However, T cells cultured with IL-12 and IL-10 did not express NK-1R. IL-10 also down-modulated ongoing NK-1R expression. Mice given NK-1R antagonist after NSAID induction of severe colitis showed nearly complete reversal of inflammation, and LP T cells ceased IFN-γ secretion. Thus, intestinal inflammation in IL-10−/− mice is associated with the appearance of NK-1R in mucosal T cells, and an interplay between IL-12 and IL-10 regulates T cell NK-1R transcription. NK-1R antagonist reverses ongoing intestinal inflammation attesting to the importance of SP and its receptor in mucosal inflammation.
SεSμ and SεSγ Switch Circles in Human Nasal Mucosa Following Ex Vivo Allergen Challenge: Evidence for Direct as Well as Sequential Class Switch Recombination
Authors: Cameron Lisa , Gounni Abdelilah Soussi , Frenkiel Saul , Lavigne François , Vercelli Donata , Hamid Qutayba
Published: April 2014

B cells switch to IgE under the influence of IL-4, IL-13, and CD40 costimulation through a multistep process involving ε germline transcription and class switch recombination. Classically, switching has been considered an event restricted to lymphoid tissues; however, ε germline transcripts (I(initiator)ε RNA) have been observed within lung, sinus, and nasal tissue of individuals with asthma, sinusitis, and rhinitis. Furthermore, nasal mucosal tissue from allergic rhinitics produces ε germline transcripts following ex vivo allergen challenge. Collectively, these studies raised the possibility that switching to IgE may occur locally, at sites of allergic inflammation. Although ε germline transcripts are considered necessary to target the IgE locus, it is class switch recombination that ultimately leads to de novo IgE production. In this study, we demonstrate that SεSμ DNA switch circles (products of class switch recombination) as well as Iε and Cε RNA are produced within nasal tissue from allergic individuals following ex vivo allergen challenge. ε germline transcription was inhibited when tissue was cultured with a combination of allergen and neutralizing Abs against IL-4 and IL-13, indicating that de novo cytokine production mediated the isotype switch. We also show allergen-induced appearance of SεSγ DNA switch circles and up-regulation of Cγ4 mRNA, illustrating that sequential switching to IgE also occurred. This work strongly suggests that B cells residing within the nasal mucosa undergo switching to IgE in the context of a local immune response to allergen.
Genetic Evidence for Involvement of Classical Complement Pathway in Induction of Experimental Autoimmune Myasthenia Gravis
Authors: Tüzün Erdem , Scott Benjamin G. , Goluszko Elzbieta , Higgs Stephen , Christadoss Premkumar
Published: April 2014

Abs to acetylcholine receptor (AChR) and complement are the major constituents of pathogenic events causing neuromuscular junction destruction in both myasthenia gravis (MG) and experimental autoimmune MG (EAMG). To analyze the differential roles of the classical vs alternative complement pathways in EAMG induction, we immunized C3−/−, C4−/−, C3+/−, and C4+/− mice and their control littermates (C3+/+ and C4+/+ mice) with AChR in CFA. C3−/− and C4−/− mice were resistant to disease, whereas mice heterozygous for C3 or C4 displayed intermediate susceptibility. Although C3−/− and C4−/− mice had anti-AChR Abs in their sera, anti-AChR IgG production by C3−/− mice was significantly suppressed. Both C3−/− and C4−/− mice had reduced levels of B cells and increased expression of apoptotis inducers (Fas ligand, CD69) and apoptotic cells in lymph nodes. Immunofluorescence studies showed that the neuromuscular junction of C3−/− and C4−/− mice lacked C3 or membrane attack complex deposits, despite having IgG deposits, thus providing in vivo evidence for the incapacity of anti-AChR IgGs to induce full-blown EAMG without the aid of complements. The data provide the first direct genetic evidence for the classical complement pathway in the induction of EAMG induced by AChR immunization. Accordingly, severe MG and other Ab- and complement-mediated diseases could be effectively treated by inhibiting C4, thus leaving the alternative complement pathway intact.
Curcumin (Diferuloylmethane) Inhibits Constitutive and IL-6-Inducible STAT3 Phosphorylation in Human Multiple Myeloma Cells
Authors: Bharti Alok C. , Donato Nicholas , Aggarwal Bharat B.
Published: April 2014

Numerous reports suggest that IL-6 promotes survival and proliferation of multiple myeloma (MM) cells through the phosphorylation of a cell signaling protein, STAT3. Thus, agents that suppress STAT3 phosphorylation have potential for the treatment of MM. In the present report, we demonstrate that curcumin (diferuloylmethane), a pharmacologically safe agent in humans, inhibited IL-6–induced STAT3 phosphorylation and consequent STAT3 nuclear translocation. Curcumin had no effect on STAT5 phosphorylation, but inhibited the IFN-α-induced STAT1 phosphorylation. The constitutive phosphorylation of STAT3 found in certain MM cells was also abrogated by treatment with curcumin. Curcumin-induced inhibition of STAT3 phosphorylation was reversible. Compared with AG490, a well-characterized Janus kinase 2 inhibitor, curcumin was a more rapid (30 min vs 8 h) and more potent (10 μM vs 100 μM) inhibitor of STAT3 phosphorylation. In a similar manner, the dose of curcumin completely suppressed proliferation of MM cells; the same dose of AG490 had no effect. In contrast, a cell-permeable STAT3 inhibitor peptide that can inhibit the STAT3 phosphorylation mediated by Src blocked the constitutive phosphorylation of STAT3 and also suppressed the growth of myeloma cells. TNF-α and lymphotoxin also induced the proliferation of MM cells, but through a mechanism independent of STAT3 phosphorylation. In addition, dexamethasone-resistant MM cells were found to be sensitive to curcumin. Overall, our results demonstrated that curcumin was a potent inhibitor of STAT3 phosphorylation, and this plays a role in the suppression of MM proliferation.
Islet Allograft Rejection in Nonobese Diabetic Mice Involves the Common γ-Chain and CD28/CD154-Dependent and -Independent Mechanisms
Authors: Demirci Gulcin , Strom Terry B. , Li Xian Chang
Published: April 2014

Once nonobese diabetic (NOD) mice become diabetic, they are highly resistant to islet transplantation. The precise mechanism of such resistance remains largely unknown. In the present study we tested the hypothesis that islet allograft survival in the diabetic NOD mouse is determined by the interplay of diverse islet-specific T cell subsets whose activation is regulated by CD28/CD154 costimulatory signals and the common γ-chain (γc; a shared signaling element by receptors for IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21). We found that common γc blockade is remarkably effective in blocking the onset and the ongoing autoimmune diabetes, whereas CD28/CD154 blockade has no effect in suppressing the ongoing diabetes. However, CD28/CD154 blockade completely blocks the alloimmune-mediated islet rejection. Also, a subset of memory-like T cells in the NOD mice is resistant to CD28/CD154 blockade, but is sensitive to the common γc blockade. Nonetheless, neither common γc blockade nor CD28/CD154 blockade can prevent islet allograft rejection in diabetic NOD mice. Treatment of diabetic NOD recipients with CD28/CD154 blockade plus γc blockade markedly prolongs islet allograft survival compared with the controls. However, allograft tolerance is not achieved, and all CTLA-4Ig-, anti-CD154-, and anti-γc-treated diabetic NOD mice eventually rejected the islet allografts. We concluded that the effector mechanisms in diabetic NOD hosts are inherently complex, and rejection in this model involves CD28/CD154/γc-dependent and -independent mechanisms.
Cutting Edge: Cyclooxygenase-2 Activation Suppresses Th1 Polarization in Response toHelicobacter pylori
Authors: Meyer Frank , Ramanujam Kalathur S. , Gobert Alain P. , James Stephen P. , Wilson Keith T.
Published: April 2014

Helicobacter pylori infection causes a Th1-driven mucosal immune response. Cyclooxygenase (COX)-2 is up-regulated in lamina propria mononuclear cells in H. pylori gastritis. Because COX-2 can modulate Th1/Th2 balance, we determined whether H. pylori activates COX-2 in human PBMCs, and the effect on cytokine and proliferative responses. There was significant up-regulation of COX-2 mRNA and PGE2 release in response to H. pylori preparations. Addition of COX-2 inhibitors or an anti-PGE2 Ab resulted in a marked increase in H. pylori-stimulated IL-12 and IFN-γ production, and a decrease in IL-10 levels. Addition of PGE2 or cAMP, the second messenger activated by PGE2, had the opposite effect. Similarly, stimulated cell proliferation was increased by COX-2 inhibitors or anti-PGE2 Ab, and was decreased by PGE2. Our findings indicate that COX-2 has an immunosuppressive role in H. pylori gastritis, which may protect the mucosa from severe injury, but may also contribute to the persistence of the infection.
Clonal Expansion of Double-Positive Intraepithelial Lymphocytes by MHC Class I-Related Chain A Expressed in Mouse Small Intestinal Epithelium
Authors: Park Eun Jeong , Takahashi Ichiro , Ikeda Junko , Kawahara Kazuko , Okamoto Tetsuji , Kweon Mi-Na , Fukuyama Satoshi , Groh Veronika , Spies Thomas , Obata Yuichi , Miyazaki Jun-Ichi , Kiyono Hiroshi
Published: April 2014

Expression of a distant homologue MHC class I molecule, MHC class I-related chain A (MICA), has been found to be stress inducible and limited to the intestinal epithelium. This nonclassical MHC molecule is associated with various carcinomas in humans. To understand the biological consequences of MICA expression in the gut, we generated transgenic (Tg) mice (T3b-MICA Tg) under the control of the T3b promoter. The T3b-MICA Tg mice expressed MICA selectively in the intestine and had an increased number of TCRαβ CD4CD8αα, double-positive (DP) intraepithelial lymphocytes (IELs) in the small bowel. These MICA-expanded DP IELs exhibited a bias to Vβ8.2 and overlapped motifs of the complementarity-determining region 3 region among various Tg mice. Hence, the overexpression of MICA resulted in a clonal expansion of DP IELs. Studies in model of inflammatory bowel disease showed that transgenic MICA was able to attenuate the acute colitis induced by dextran sodium sulfate administration. Therefore, this unique in vivo model will enable investigation of possible influences of stress-inducible MICA on the gut immune surveillance.
The Rac-Activating Toxin Cytotoxic Necrotizing Factor 1 Oversees NK Cell-Mediated Activity by Regulating the Actin/Microtubule Interplay
Authors: Malorni W. , Quaranta M. G. , Straface E. , Falzano L. , Fabbri A. , Viora M. , Fiorentini C.
Published: April 2014

The cell cytoskeleton is widely acknowledged as a master for NK cell function. Specifically, actin filaments guide the NK cell binding to target cells, engendering the formation of the so-called immunological synapse, while microtubules direct the killer behavior. All these cytoskeleton-dependent activities are competently governed by the Rho GTPases, a family of regulatory molecules encompassing the three different subfamilies, Rho, Rac, and Cdc42. By using a Rac GTPase-activating bacterial protein toxin from Escherichia coli named cytotoxic necrotizing factor 1 (CNF1), we obtained results supporting the activation of Rac GTPase as a booster for effector cell-binding efficiency, recruitment ability, and, consequently, cytotoxicity. In particular, the augmented killer capacity of CNF1-treated NK cells was associated with the increased expression of certain cell adhesion or activation-associated molecules and the reshaping of the actin and microtubule networks. Importantly, CNF1 counteracted the activity exerted by toxins disrupting the cytoskeletal architecture. Hence, the activation of Rho GTPases, particularly Rac, induced by CNF1, appears to orchestrate a dynamic cross talk between microtubules and actin filaments, leading to a fruitful NK cell activity and polarization state. Our findings suggest that protein toxins might be viewed as modulators of NK cell cytotoxic activity and could possibly be regarded as useful pharmacological tools for certain Rho-linked immune diseases in the near future.
NF-κB RegulatesBCL3Transcription in T Lymphocytes Through an Intronic Enhancer
Authors: Ge Baosheng , Li Olga , Wilder Phillip , Rizzino Angie , McKeithan Timothy W.
Published: April 2014

Exposure to soluble protein Ags in vivo leads to abortive proliferation of responding T cells. In the absence of a danger signal, artificially provided by adjuvants, most responding cells die, and the remainder typically become anergic. The adjuvant-derived signals provided to T cells are poorly understood, but recent work has identified BCL3 as the gene, of those tested, with the greatest differential transcriptional response to adjuvant administration in vivo. As an initial step in analyzing transcriptional responses of BCL3 in T cells, we have identified candidate regulatory regions within the locus through their evolutionary conservation and by analysis of DNase hypersensitivity. An evolutionarily conserved DNase hypersensitive site (HS3) within intron 2 was found to act as a transcriptional enhancer in response to stimuli that mimic TCR activation, namely, PHA and PMA. In luciferase reporter gene constructs transiently transfected into the Jurkat T cell line, the HS3 enhancer can cooperate not only with the BCL3 promoter, but also with an exogenous promoter from herpes simplex thymidine kinase. Deletional analysis revealed that a minimal sequence of ∼81 bp is required for full enhancer activity. At the 5′ end of this minimal sequence is a κB site, as confirmed by EMSAs. Mutation of this site in the context of the full-length HS3 abolished enhancer activity. Cotransfection with NF-κB p65 expression constructs dramatically increased luciferase activity, even without stimulation. Conversely, cotransfection with the NF-κB inhibitor IκBα reduced activation. Together, these results demonstrate a critical role for NF-κB in BCL3 transcriptional up-regulation by TCR-mimetic signals.
Transcriptional Control of MurineCD94Gene: Differential Usage of Dual Promoters by Lymphoid Cell Types
Authors: Wilhelm Brian T. , Landry Josette-Renée , Takei Fumio , Mager Dixie L.
Published: April 2014

The CD94 gene product is involved in controlling NK cell activation, and is one of a family of immune receptors that is found in the NK gene complex in both humans and mice, adjacent to members of the NKG2 family. CD94 forms a heterodimeric complex with several members of the NKG2 family on the surface of NK, T, and NKT cells. These complexes recognize the nonclassical MHC class I molecules HLA-E and Qa-1b in humans and mice, respectively. The mechanism for cell type-specific expression of CD94 and other genes from the NK gene complex has not yet been elucidated. In the current study, we show that the murine CD94 gene has two promoters, one of which is upstream of a previously unidentified exon. We illustrate by quantitative real-time PCR that lymphoid cell types use these two promoters differentially and that the promoter usage seen in adult cells is already established during fetal development. We determined that the differential promoter usage by NK cells appears to be susceptible to perturbation, as both the murine NK cell line LNK, as well as cultured C57BL/6 NK cells showed altered promoter usage relative to fresh NK cells. Furthermore, the promoter activity observed in transfection assays did not correlate with expression of the endogenous CD94 gene, suggesting the involvement of chromatin structure/methylation in transcriptional regulation. Our detection of DNase I hypersensitive sites at the CD94 locus that are present only in a cell line expressing endogenous CD94 supports this hypothesis.
Blockade of Airway Inflammation and Hyperresponsiveness by HIV-TAT-Dominant Negative Ras
Authors: Myou Shigeharu , Zhu Xiangdong , Myo Saori , Boetticher Evan , Meliton Angelo Y. , Liu Jie , Munoz Nilda M. , Leff Alan R.
Published: April 2014

We have reported previously that HIV-TAT-dominant negative (dn) Ras inhibits eosinophil adhesion to ICAM-1 after activation by IL-5 and eotaxin. In this study, we evaluated the role of Ras in Ag-induced airway inflammation and hyperresponsiveness by i.p. administration into mice of dnRas, which was fused to an HIV-TAT protein transduction domain (TAT-dnRas). Uptake of TAT-dnRas (t1/2 = 12 h) was demonstrated in leukocytes after i.p. administration. OVA-sensitization significantly increased eosinophil and lymphocyte numbers in bronchoalveolar lavage fluid 24 h after final challenge. Treatment of animals with 3–10 mg/kg TAT-dnRas blocked the migration of eosinophils from 464 ± 91 × 103/ml to 288 ± 79 × 103/ml with 3 mg/kg of TAT-dnRas (p < 0.05), and further decreased to 116 ± 63 × 103/ml after 10 mg/kg TAT-dnRas (p < 0.01). Histological examination demonstrated that inflammatory cell infiltration (largely eosinophils and mononuclear cells) and mucin production around the airways caused by OVA were blocked by TAT-dnRas. OVA challenge also caused airway hyperresponsiveness to methacholine, which was dose dependently blocked by treatment with TAT-dnRas. TAT-dnRas also blocked Ag-induced IL-4 and IL-5, but not IFN-γ, production in lung tissue. Intranasal administration of IL-5 caused eosinophil migration into the airway lumen, which was attenuated by pretreatment with TAT-dnRas. By contrast, TAT-green fluorescent protein or dnRas lacking the TAT protein transduction domain did not block airway inflammation, cytokine production, or airway hyperresponsiveness. We conclude that Ras mediates Th2 cytokine production, airway inflammation, and airway hyperresponsiveness in immune-sensitized mice.
IL-8/CXCL8 and Growth-Related Oncogene α/CXCL1 Induce Chondrocyte Hypertrophic Differentiation
Authors: Merz Denise , Liu Ru , Johnson Kristen , Terkeltaub Robert
Published: April 2014

Foci of chondrocyte hypertrophy that commonly develop in osteoarthritic (OA) cartilage can promote dysregulated matrix repair and pathologic calcification in OA. The closely related chemokines IL-8/CXCL8 and growth-related oncogene α (GROα)/CXCL1 and their receptors are up-regulated in OA cartilage chondrocytes. Because these chemokines regulate leukocyte activation through p38 mitogen-activated protein kinase signaling, a pathway implicated in chondrocyte hypertrophic differentiation, we tested whether IL-8 and GROα promote chondrocyte hypertrophy. We observed that normal human and bovine primary articular chondrocytes expressed both IL-8Rs (CXCR1, CXCR2). IL-8 and the selective CXCR2 ligand GROα (10 ng/ml) induced tissue inhibitor of metalloproteinase-3 expression, markers of hypertrophy (type X collagen and MMP-13 expression, alkaline phosphatase activity), as well as matrix calcification. IL-8 and the selective CXCR2 ligand GROα also induced increased transamidation activity of chondrocyte transglutaminases (TGs), enzymes up-regulated in chondrocyte hypertrophy that have the potential to modulate differentiation and calcification. Under these conditions, p38 mitogen-activated protein kinase pathway signaling mediated induction of both type X collagen and TG activity. Studies using mouse knee chondrocytes lacking one of the two known articular chondrocyte-expressed TG isoenzymes (TG2) demonstrated that TG2 was essential for murine GROα homologue KC-induced TG activity and critically mediated induction by KC of type X collagen, matrix metalloproteinase-13, alkaline phosphatase, and calcification. In conclusion, IL-8 and GROα induce articular chondrocyte hypertrophy and calcification through p38 and TG2. Our results suggest a novel linkage between inflammation and altered differentiation of articular chondrocytes. Furthermore, CXCR2 and TG2 may be sites for intervention in the pathogenesis of OA.
Thymocyte Sensitivity and Supramolecular Activation Cluster Formation Are Developmentally Regulated: A Partial Role for Sialylation
Authors: Starr Timothy K. , Daniels Mark A. , Lucido Michelle M. , Jameson Stephen C. , Hogquist Kristin A.
Published: April 2014

TCR reactivity is tuned during thymic development. Immature thymocytes respond to low-affinity self-ligands resulting in positive selection. Following differentiation, T cells no longer respond to low-affinity ligands, but respond well to high-affinity (foreign) ligands. We show in this study that this response includes integrin activation, supramolecular activation cluster formation, Ca2+ flux, and CD69 expression. Because glycosylation patterns are known to change during T cell development, we tested whether alterations in sialylation influence CD8 T cell sensitivity to low affinity TCR ligands. Using neuraminidase treatment or genetic deficiency in the ST3Gal-I sialyltransferase, we show that desialylation of mature CD8 T cells enhances their sensitivity to low-affinity ligands, although these treatments do not completely recapitulate the dynamic range of immature T cells. These studies identify sialylation as one of the factors that regulate CD8 T cell tuning during development.
CD8+αβ+ T Cells That Lack Surface CD5 Antigen Expression Are a Major Lymphotactin (XCL1) Source in Peripheral Blood Lymphocytes
Authors: Stievano Laura , Tosello Valeria , Marcato Novella , Rosato Antonio , Sebelin Annalisa , Chieco-Bianchi Luigi , Amadori Alberto
Published: April 2014

To better characterize the cellular source of lymphotactin (XCL1), we compared XCL1 expression in different lymphocyte subsets by real-time PCR. XCL1 was constitutively expressed in both PBMC and CD4+ cells, but its expression was almost 2 log higher in CD8+ cells. In vitro activation was associated with a substantial increase in XCL1 expression in both PBMC and CD8+ cells, but not in CD4+ lymphocytes. The preferential expression of XCL1 in CD8+ cells was confirmed by measuring XCL1 production in culture supernatants, and a good correlation was found between figures obtained by real-time PCR and XCL1 contents. XCL1 expression was mostly confined to a CD3+CD8+ subset not expressing CD5, where XCL1 expression equaled that shown by γδ+ T cells. Compared with the CD5+ counterpart, CD3+CD8+CD5− cells, which did not express CD5 following in vitro activation, showed preferential expression of the αα form of CD8 and a lower expression of molecules associated with a noncommitted/naive phenotype, such as CD62L. CD3+CD8+CD5− cells also expressed higher levels of the XCL1 receptor; in addition, although not differing from CD3+CD8+CD5+ cells in terms of the expression of most α- and β-chemokines, they showed higher expression of CCL3/macrophage inflammatory protein-1α. These data show that TCR αβ-expressing lymphocytes that lack CD5 expression are a major XCL1 source, and that the contribution to its synthesis by different TCR αβ-expressing T cell subsets, namely CD4+ lymphocytes, is negligible. In addition, they point to the CD3+CD8+CD5− population as a particular T cell subset within the CD8+ compartment, whose functional properties deserve further attention.
Another View of T Cell Antigen Recognition: Cooperative Engagement of Glycolipid Antigens by Va14Ja18 Natural TCR
Authors: Stanic Aleksandar K. , Shashidharamurthy R. , Bezbradica Jelena S. , Matsuki Naoto , Yoshimura Yoshitaka , Miyake Sachiko , Choi Eun Young , Schell Todd D. , Van Kaer Luc , Tevethia Satvir S. , Roopenian Derry C. , Yamamura Takashi , Joyce Sebastian
Published: April 2014

Va14Ja18 natural T (iNKT) cells rapidly elicit a robust effector response to different glycolipid Ags, with distinct functional outcomes. Biochemical parameters controlling iNKT cell function are partly defined. However, the impact of iNKT cell receptor β-chain repertoire and how α-galactosylceramide (α-GalCer) analogues induce distinct functional responses have remained elusive. Using altered glycolipid ligands, we discovered that the Vb repertoire of iNKT cells impacts recognition and Ag avidity, and that stimulation with suboptimal avidity Ag results in preferential expansion of high-affinity iNKT cells. iNKT cell proliferation and cytokine secretion, which correlate with iNKT cell receptor down-regulation, are induced within narrow biochemical thresholds. Multimers of CD1d1-αGalCer- and αGalCer analogue-loaded complexes demonstrate cooperative engagement of the Va14Ja18 iNKT cell receptor whose structure and/or organization appear distinct from conventional αβ TCR. Our findings demonstrate that iNKT cell functions are controlled by affinity thresholds for glycolipid Ags and reveal a novel property of their Ag receptor apparatus that may have an important role in iNKT cell activation.