bluuebunny/crossref_metadata_2025 huggingface dataset:
Macrophage Effector Functions Controlled by Bruton’s Tyrosine Kinase Are More Crucial Than the Cytokine Balance of T Cell Responses for Microfilarial Clearance
Authors: Mukhopadhyay Sangita , Mohanty Madhuchhanda , Mangla Anita , George Anna , Bal Vineeta , Rath Satyajit , Ravindran Balachandran
Published: April 2014

Macrophages from X-linked immunodeficient (xid) mice lacking functional Bruton’s tyrosine kinase (Btk) show poor NO induction and enhanced IL-12 induction, and contribute to delayed clearance of injected microfilaria (mf) in vivo. We now show that Btk is involved in other macrophage effector functions, such as bactericidal activity and secretion of proinflammatory cytokines (TNF-α, IL-1β), but not the T cell-directed cytokine IL-12. Induction of some transcriptional regulators of the NF-κB family, crucial for the expression of proinflammatory cytokines, is also poor in Btk-deficient macrophages. Thus, Btk appears to be involved in signaling for inducible effector functions, but not APC functions, in macrophages. Furthermore, adoptive transfer of T cells from mf-infected xid or wild-type mice did not alter the course of mf clearance in recipients, mf clearance was unaltered in IFN-γ-deficient mice, and improved mf clearance was seen only if greater inducibility of IL-12 was accompanied by greater NO secretion from macrophages, as seen in Ityr C.D2 mice as compared with congenic Itys BALB/c mice. Thus, delayed mf clearance in xid mice was correlated not with the high IL-12/Th1 phenotype but with low NO induction levels. Also, xid macrophages showed poor toxicity to mf in vitro as compared with wild-type macrophages. Inhibition of NO production blocked this mf cytotoxicity, and an NF-κB inhibitor blocked both NO induction and mf cytotoxicity. Thus, Btk is involved in inducing many macrophage effector functions, and delayed mf clearance seen in Btk-deficient xid mice is due to poor NO induction in macrophages, resulting in compromised microfilarial toxicity.
Recruitment Kinetics and Composition of Antibody-Secreting Cells Within the Central Nervous System Following Viral Encephalomyelitis
Authors: Tschen Shuen-Ing , Bergmann Cornelia C. , Ramakrishna Chandran , Morales Shawn , Atkinson Roscoe , Stohlman Stephen A.
Published: April 2014

Infection by the neurotropic JHM strain of mouse hepatitis virus produces an acute demyelinating encephalomyelitis. While cellular immunity initially eliminates infectious virus, CNS viral persistence is predominantly controlled by humoral immunity. To better understand the distinct phases of immune control within the CNS, the kinetics of humoral immune responses were determined in infected mice. Early during clearance of the JHM strain of mouse hepatitis virus, only few virus-specific Ab-secreting cells (ASC) were detected in the periphery or CNS, although mature B cells and ASC without viral specificity were recruited into the CNS concomitant with T cells. Serum antiviral Ab and CNS virus-specific ASC became prominent only during final elimination of infectious virus. Virus-specific ASC peaked in lymphoid organs before the CNS, suggesting peripheral B cell priming and maturation. Following elimination of infectious virus, virus-specific ASC continued to increase within the CNS and then remained stable during persistence, in contrast to declining T cell numbers. These data comprise three novel findings. Rapid recruitment of B cells in the absence of specific Ab secretion supports a potential Ab-independent effector function involving lysis of virus-infected cells. Delayed recruitment relative to viral clearance and subsequent maintenance of a stable CNS ASC population demonstrate differential regulation of T and B lymphocytes within the infected CNS. This supports a critical role of humoral immunity in regulating viral CNS persistence. Lastly, altered antiviral ASC specificities following clearance of infectious virus suggest ongoing recruitment of peripheral memory cells and/or local B cell differentiation.
IL-13-Induced Chemokine Responses in the Lung: Role of CCR2 in the Pathogenesis of IL-13-Induced Inflammation and Remodeling
Authors: Zhu Zhou , Ma Bing , Zheng Tao , Homer Robert J. , Lee Chun Geun , Charo Israel F. , Noble Paul , Elias Jack A.
Published: April 2014

IL-13 stimulates inflammatory and remodeling responses and contributes to the pathogenesis of human airways disorders. To further understand the cellular and molecular events that mediate these responses, we characterized the effects of IL-13 on monocyte chemotactic proteins (MCPs) and compared the tissue effects of transgenic IL-13 in mice with wild-type (+/+) and null (−/−) CCR2 loci. Transgenic IL-13 was a potent stimulator of MCP-1, -2, -3, and -5. This stimulation was not specific for MCPs because macrophage-inflammatory protein (MIP)-1α, MIP-1β, MIP-2, MIP-3α, thymus- and activation-regulated chemokine, thymus-expressed chemokine, eotaxin, eotaxin 2, macrophage-derived chemokines, and C10 were also induced. The ability of IL-13 to increase lung size, alveolar size, and lung compliance, to stimulate pulmonary inflammation, hyaluronic acid accumulation, and tissue fibrosis, and to cause respiratory failure and death were markedly decreased, whereas mucus metaplasia was not altered in CCR2−/− mice. CCR2 deficiency did not decrease the basal or IL-13-stimulated expression of target matrix metalloproteinases or cathepsins but did increase the levels of mRNA encoding α1-antitrypsin, tissue inhibitor of metalloproteinase-1, -2, and -4, and secretory leukocyte proteinase inhibitor. In addition, the levels of bioactive and total TGF-β1 were decreased in lavage fluids from IL-13 transgenic mice with −/− CCR2 loci. These studies demonstrate that IL-13 is a potent stimulator of MCPs and other CC chemokines and document the importance of MCP-CCR2 signaling in the pathogenesis of the IL-13-induced pulmonary phenotype.
Activation of Nuclear Orphan Receptor NURR1 Transcription by NF-κB and Cyclic Adenosine 5′-Monophosphate Response Element-Binding Protein in Rheumatoid Arthritis Synovial Tissue
Authors: McEvoy Alice N. , Murphy Eithne A. , Ponnio Tiia , Conneely Orla M. , Bresnihan Barry , FitzGerald Oliver , Murphy Evelyn P.
Published: April 2014

Modulation of the NURR subfamily of nuclear receptors may be an important mechanism regulating pathways associated with inflammatory joint disease. We examined the signaling mechanisms through which inflammatory mediators, produced by rheumatoid arthritis (RA) synovial tissue, contribute to the regulation of the NURR subfamily. Markedly enhanced expression of NURR1 is observed in synovial tissue of patients with RA compared with normal subjects. Modulation by proinflammatory mediators in primary RA and normal synoviocytes shows that PGE2, IL-1β, and TNF-α markedly enhance NURR1 mRNA and protein levels in contrast to other subfamily members, NUR77 and NOR-1. We have established that transcriptional activation of the NURR1 gene by IL-1β and TNF-α requires a proximal promoter region that contains a consensus NF-κB DNA-binding motif. IL-1β- and TNF-α-induced NF-κB binding to this site is due predominantly to p65-p50 heterodimer and p50 homodimer subunit protein complexes. We further demonstrate a direct CREB-1-dependent regulation by PGE2 situated at promoter region −171/−163. Moreover, analyses confirm the presence of CREB-1 and NF-κB p50 and p65 subunit binding to the NURR1 promoter under basal conditions in freshly explanted RA synovial tissue. In summary, enhanced NF-κB- and CREB-1-binding activity on the NURR1 promoter by inflammatory mediators delineates novel mechanisms in the regulation of NURR1 transcription. PGE2-, TNF-α-, and IL-1β-dependent stimulation of the NURR1 gene implies that NURR1 induction represents a point of convergence of at least two distinct signaling pathways, suggesting an important common role for this transcription factor in mediating multiple inflammatory signals.
Pathogenesis of Murine Experimental Allergic Rhinitis: A Study of Local and Systemic Consequences of IL-5 Deficiency
Authors: Saito Hiroko , Matsumoto Koichiro , Denburg Avram E. , Crawford Lynn , Ellis Russ , Inman Mark D. , Sehmi Roma , Takatsu Kiyoshi , Matthaei Klaus I. , Denburg Judah A.
Published: April 2014

Recent studies have demonstrated an important role for IL-5-dependent bone marrow eosinophil progenitors in allergic inflammation. However, studies using anti-IL-5 mAbs in human asthmatics have failed to suppress lower airway hyperresponsiveness despite suppression of eosinophilia; therefore, it is critical to examine the role of IL-5 and bone marrow responses in the pathogenesis of allergic airway disease. To do this, we studied the effects of IL-5 deficiency (IL-5−/−) on bone marrow function as well as clinical and local events, using an established experimental murine model of allergic rhinitis. Age-matched IL-5+/+ and IL-5−/− BALB/c mice were sensitized to OVA followed by 2 wk of daily OVA intranasal challenge. IL-5−/− OVA-sensitized mice had significantly higher nasal mucosal CD4+ cells and basophilic cell counts as well as nasal symptoms and histamine hyperresponsiveness than the nonsensitized group; however, there was no eosinophilia in either nasal mucosa or bone marrow; significantly lower numbers of eosinophil/basophil CFU and maturing CFU eosinophils in the presence of recombinant mouse IL-5 in vitro; and significantly lower expression of IL-5Rα on bone marrow CD34+CD45+ progenitor cells in IL-5−/− mice. These findings suggest that IL-5 is required for normal bone marrow eosinophilopoiesis, in response to specific Ag sensitization, during the development of experimental allergic rhinitis. However, the results also suggest that suppression of the IL-5-eosinophil pathway in this model of allergic rhinitis may not completely suppress clinical symptoms or nasal histamine hyperresponsiveness, because of the existence of other cytokine-progenitor pathways that may induce and maintain the presence of other inflammatory cell populations.
Antimicrobial Peptides Initiate IL-1β Posttranslational Processing: A Novel Role Beyond Innate Immunity
Authors: Perregaux David G. , Bhavsar Kanan , Contillo Len , Shi Jishu , Gabel Christopher A.
Published: April 2014

Human monocytes stimulated with LPS produce large quantities of prointerleukin-1β, but little of this cytokine product is released extracellularly as the mature biologically active species. To demonstrate efficient proteolytic cleavage and export, cytokine-producing cells require a secondary effector stimulus. In an attempt to identify agents that may serve as initiators of IL-1β posttranslational processing in vivo, LPS-activated human monocytes were treated with several individual antimicrobial peptides. Two peptides derived from porcine neutrophils, protegrin (PTG)-1 and PTG-3, promoted rapid and efficient release of mature IL-1β. The PTG-mediated response engaged a mechanism similar to that initiated by extracellular ATP acting via the P2X7 receptor. Thus, both processes were disrupted by a caspase inhibitor, both were sensitive to ethacrynic acid and CP-424,174, two pharmacological agents that suppress posttranslational processing, and both were negated by elevation of extracellular potassium. Moreover, the PTGs, like ATP, promoted a dramatic change in monocyte morphology and a loss of membrane latency. The PTG response was concentration dependent and was influenced profoundly by components within the culture medium. In contrast, porcine neutrophil antimicrobial peptides PR-26 and PR-39 did not initiate IL-1β posttranslational processing. The human defensin HNP-1 and the frog peptide magainin 1 elicited export of 17-kDa IL-1β, but these agents were less efficient than PTGs. As a result of this ability to promote release of potent proinflammatory cytokines such as IL-1β, select antimicrobial peptides may possess important immunomodulatory functions that extend beyond innate immunity.
TheHelicobacter pyloriBlood Group Antigen-Binding Adhesin Facilitates Bacterial Colonization and Augments a Nonspecific Immune Response
Authors: Rad Roland , Gerhard Markus , Lang Roland , Schöniger Martin , Rösch Thomas , Schepp Wolfgang , Becker Ingrid , Wagner Hermann , Prinz Christian
Published: April 2014

Presence of the Helicobacter pylori adherence factor blood group Ag-binding adhesin (BabA; binding to Lewisb (Leb)) is associated with ulcer disease, adenocarcinoma, and precancerous lesions. The importance of BabA for bacterial colonization and the inflammatory response is unknown. A total of 141 antral biopsies from H. pylori-infected patients were assessed in regard to the degree of granulocytic (G0°–G3°) and lymphocytic (L1°–L3°) infiltration. DNA genotypes of babA2 (the transcriptionally active gene of BabA), cagA, and vacAs1/2 were determined by PCR. Colonization density and Leb status on gastric epithelial cells were determined by immunohistochemistry. Real-time quantitative (TaqMan) RT-PCR determined mRNA expression of IL-8, TNF -α, and the Th1 markers IFN-γ and the IL-12R β2 chain. A total of 91% of infected patients were Leb positive. The vacAs1+/cagA+ strains harboring babA2 showed significantly higher levels of granulocytic infiltration, bacterial colonization, and IL-8 mRNA than vacAs1+/cagA+ strains lacking babA2. IL-8 mRNA and protein production by KATO III cells in vitro increased dose dependently with addition of different numbers of type 1 strains (G27 and 2808 strains, 0.1–20 bacteria/cell). The mRNA expression of TNF-α, IFN-γ, and IL-12R β2 was higher in H. pylori-positive patients than in controls, but it did not differ significantly between patients infected with different strain types. These data suggest that BabA facilitates colonization of H. pylori and thereby increases IL-8 response, resulting in enhanced mucosal inflammation. Infection with strains harboring BabA thereby augment a nonspecific immune response, whereas the Th1 response toward H. pylori appears to be independent of BabA, cytotoxin-associated gene A, or vacuolating cytotoxin.
A Novel Susceptibility Locus On Chromosome 2 in the (New Zealand Black × New Zealand White)F1 Hybrid Mouse Model of Systemic Lupus Erythematosus
Authors: Rahman Ziaur SM. , Tin Soe-Kyaw , Buenaventura Pia-Nina L. , Ho Chiu-Han , Yap Eric P. H. , Yong Rita Y. Y. , Koh Dow-Rhoon
Published: April 2014

Systemic lupus erythematosus (SLE) is inherited as a complex polygenic trait. (New Zealand Black (NZB) × New Zealand White (NZW)) F1 hybrid mice develop symptoms that remarkably resemble human SLE, but (NZB × PL/J)F1 hybrids do not develop lupus. Our study was conducted using (NZW × PL/J)F1 × NZB (BWP) mice to determine the effects of the PL/J and the NZW genome on disease. Forty-five percent of BWP female mice had significant proteinuria and 25% died before 12 mo of age compared with (NZB × NZW)F1 mice in which >90% developed severe renal disease and died before 12 mo. The analysis of BWP mice revealed a novel locus (χ2 = 25.0; p < 1 × 10−6; log of likelihood = 6.6 for mortality) designated Wbw1 on chromosome 2, which apparently plays an important role in the development of the disease. We also observed that both H-2 class II (the u haplotype) and TNF-α (TNFz allele) appear to contribute to the disease. A suggestive linkage to proteinuria and death was found for an NZW allele (designated Wbw2) telomeric to the H-2 locus. The NZW allele that overlaps with the previously described locus Sle1c at the telomeric part of chromosome 1 was associated with antinuclear autoantibody production in the present study. Furthermore, the previously identified Sle and Lbw susceptibility loci were associated with an increased incidence of disease. Thus, multiple NZW alleles including the Wbw1 allele discovered in this study contribute to disease induction, in conjunction with the NZB genome, and the PL/J genome appears to be protective.
TNF-TNFR2 Interactions Are Critical for the Development of Intestinal Graft-Versus-Host Disease in MHC Class II-Disparate (C57BL/6J→C57BL/6J × bm12)F1 Mice
Authors: Brown Geri R. , Lee Ed , Thiele Dwain L.
Published: April 2014

TNF-TNFR2 interactions promote MHC class II-stimulated alloresponses while TNF-TNFR1 interactions promote MHC class I-stimulated alloresponses. The present studies were designed to evaluate whether TNF-TNFR2 interactions were involved in the in vivo generation of CD4+ T cell-mediated intestinal graft-versus-host disease (GVHD) in the (C57BL/6J (hereafter called B6)→B6 × B6.C-H-2bm12 (bm12))F1 GVHD model. Briefly, 5 × 106 splenic CD4+ T lymphocytes from B6.TNFR2−/− or control B6 mice were transferred with 1–2 × 106 T cell-depleted B6 bone marrow cells (BMC) to irradiated MHC class II-disparate (bm12 × B6)F1 mice. Weight loss, intestinal inflammation, and the surface expression of CD45RB (memory marker) on intestinal and splenic lymphocytes were assessed. IL-2 and IFN-α mRNA levels in intestinal lymphocytes were assessed by nuclease protection assays. A significant reduction in weight loss and intestinal inflammation was observed in recipients of the TNFR2−/−CD4+ SpC. Similarly, a significant decrease was noted in T cell numbers and in CD45RBlow (activated/memory) expression on intestinal but not CD4+ T cells in recipients of TNFR2−/−CD4+ spleen cells. IL-2 and IFN-α mRNA levels were reduced in the intestine in the recipients of TNFR2−/− splenic CD4+ T cells. These results indicate that TNF-TNFR2 interactions are important for the development of intestinal inflammation and activation/differentiation of Th1 cytokine responses by intestinal lymphocytes in MHC class II-disparate GVHD while playing an insignificant role in donor T cell activation in the spleen.
Skin Inflammation During Contact Hypersensitivity Is Mediated by Early Recruitment of CD8+ T Cytotoxic 1 Cells Inducing Keratinocyte Apoptosis
Authors: Akiba Hitoshi , Kehren Jeanne , Ducluzeau Marie-Thérèse , Krasteva Maya , Horand Françoise , Kaiserlian Dominique , Kaneko Fumio , Nicolas Jean-François
Published: April 2014

Contact hypersensitivity (CHS) is a T cell-mediated, Ag-specific skin inflammation induced by skin exposure to haptens in sensitized individuals. Th1/T cytotoxic 1 cells are effector cells of CHS, whereas Th2/T regulatory CD4+ T cells have down-regulating properties. We have previously shown that CHS to 2,4-dinitrofluorobenzene is mediated by specific CD8+ effector cells, whose cytolytic activity is mandatory for induction of skin inflammation. In this study, using immunohistochemistry and RT-PCR analysis, we show that CD8+ T cells are rapidly recruited into the skin at the site of hapten challenge before the onset of clinical and histological signs of skin inflammation. This early CD8+ T cell recruitment is concomitant with: 1) transient IFN-γ mRNA expression suggesting local activation of effector cells; and 2) induction of keratinocyte (KC) apoptosis which gradually increased to a maximum at the peak of the CHS response. Alternatively, skin infiltration of CD4+ T cells occurred later and coincided with the peak of the CHS reaction and the beginning of the resolution of skin inflammation. Mice deficient in CD8+ T cells did not develop CHS, whereas mice deficient in CD4+ T cells developed an enhanced inflammatory response with increased numbers of CD8+ T cells recruited in the skin associated with massive KC apoptosis. These data show that CHS is due to the early and selective recruitment in the skin of CD8+ T cytotoxic 1 effector cells responsible for KC apoptosis.
Syk Regulation of Phosphoinositide 3-Kinase-Dependent NK Cell Function
Authors: Jiang Kun , Zhong Bin , Gilvary Danielle L. , Corliss Brian C. , Vivier Eric , Hong-Geller Elizabeth , Wei Sheng , Djeu Julie Y.
Published: April 2014

Emerging evidence suggests that NK-activatory receptors use KARAP/DAP12, CD3ζ, and FcεRIγ adaptors that contain immunoreceptor tyrosine-based activatory motifs to mediate NK direct lysis of tumor cells via Syk tyrosine kinase. NK cells may also use DAP10 to drive natural cytotoxicity through phosphoinositide 3-kinase (PI3K). In contrast to our recently identified PI3K pathway controlling NK cytotoxicity, the signaling mechanism by which Syk associates with downstream effectors to drive NK lytic function has not been clearly defined. In NK92 cells, which express DAP12 but little DAP10/NKG2D, we now show that Syk acts upstream of PI3K, subsequently leading to the specific signaling of the PI3K→Rac1→PAK1→mitogen-activated protein/extracellular signal-regulated kinase (ERK) kinase→ERK cascade that we earlier described. Tumor cell ligation stimulated DAP12 tyrosine phosphorylation and its association with Syk in NK92 cells; Syk tyrosine phosphorylation and activation were also observed. Inhibition of Syk function by kinase-deficient Syk or piceatannol blocked target cell-induced PI3K, Rac1, PAK1, mitogen-activated protein/ERK kinase, and ERK activation, perforin movement, as well as NK cytotoxicity, indicating that Syk is upstream of all these signaling events. Confirming that Syk does not act downstream of PI3K, constitutively active PI3K reactivated all the downstream effectors as well as NK cytotoxicity suppressed in Syk-impaired NK cells. Our results are the first report documenting the instrumental role of Syk in control of PI3K-dependent natural cytotoxicity.
Suppressors of Cytokine Signaling Proteins Are Differentially Expressed in Th1 and Th2 Cells: Implications for Th Cell Lineage Commitment and Maintenance
Authors: Egwuagu Charles E. , Yu Cheng-Rong , Zhang Meifen , Mahdi Rashid M. , Kim Stephen J. , Gery Igal
Published: April 2014

Positive regulatory factors induced by IL-12/STAT4 and IL-4/STAT6 signaling during T cell development contribute to polarized patterns of cytokine expression manifested by differentiated Th cells. These two critical and antagonistic signaling pathways are under negative feedback regulation by a multimember family of intracellular proteins called suppressor of cytokine signaling (SOCS). However, it is not known whether these negative regulatory factors also modulate Th1/Th2 lineage commitment and maintenance. We show here that CD4+ naive T cells constitutively express low levels of SOCS1, SOCS2, and SOCS3 mRNAs. These mRNAs and their proteins increase significantly in nonpolarized Th cells after activation by TCR signaling. We further show that differentiation into Th1 or Th2 phenotype is accompanied by preferential expression of distinct SOCS mRNA transcripts and proteins. SOCS1 expression is 5-fold higher in Th1 than in Th2 cells, whereas Th2 cells contain 23-fold higher levels of SOCS3. We also demonstrate that IL-12-induced STAT4 activation is inhibited in Th2 cells that express high levels of SOCS3 whereas IL-4/STAT6 signaling is constitutively activated in Th2 cells, but not Th1 cells, with high SOCS1 expression. These results suggest that mutually exclusive use of STAT4 and STAT6 signaling pathways by differentiated Th cells may derive in part, from SOCS3- or SOCS1-mediated repression of IL-12/STAT4- or IL-4/STAT6 signaling in Th2 and Th1 cells, respectively. Given the strong correlation between distinct patterns of SOCS expression and differentiation into the Th1 or Th2 phenotype, SOCS1 and SOCS3 proteins are therefore Th lineage markers that can serve as therapeutic targets for immune modulation therapy.
Autoreactive T Cells Revealed in the Normal Repertoire: Escape from Negative Selection and Peripheral Tolerance
Authors: Yan Jun , Mamula Mark J.
Published: April 2014

Self-reactive T cells are known to be eliminated by negative selection in the thymus or by the induction of tolerance in the periphery. However, developmental pathways that allow self-reactive T cells to inhabit the normal repertoire are not well-characterized. In this investigation, we made use of anti-small nuclear ribonucleoprotein particle (snRNP) Ig transgenic (Tg) mice (2-12 Tg) to demonstrate that autoreactive T cells can be detected and activated in both normal naive mice and autoimmune-prone MRL lpr/lpr mice. In contrast, autoreactive T cells of nonautoimmune Tg mice are tolerized by Tg B cells in the periphery. In adoptive transfer studies, autoreactive T cells from MRL lpr/lpr mice can stimulate autoantibody synthesis in nonautoimmune anti-snRNP Tg mice. Transferred CD4 T cells migrate to regions of the spleen proximal to the B cell follicles, suggesting that cognate B cell-T cell interactions are critical to the autoimmune response. Taken together, our studies suggest that anti-snRNP B cells are important APCs for T cell activation in autoimmune-prone mice. Additionally, we have demonstrated that anti-snRNP B cell anergy in nonautoimmune mice may be reversed by appropriate T cell help.
Functional Consequences of Noncognate Interactions Between CD4+ Memory T Lymphocytes and the Endothelium
Authors: Berg Lutz-Peter , James Martha J. , Alvarez-Iglesias Montserrat , Glennie Sarah , Lechler Robert I. , Marelli-Berg Federica M.
Published: April 2014

The recruitment of Ag-specific T cells to sites of inflammation is a crucial step in immune surveillance. Although the molecular interactions controlling T cell extravasation are relatively well characterized, the effects of these events on T cell function are still poorly understood. Using an in vitro model of transendothelial migration of human CD4+ memory T cells, we have investigated the molecular and functional changes induced in T cells that come into contact with the endothelium. First, we show that transendothelial migration is precluded by signals that lead to T cell division. In addition, activation of the transcription factor AP-1, without induction of NF-κB, is observed in T cells after noncognate interactions with endothelial cells (EC), a pattern of transcriptional regulation different from that observed in dividing T cells. Up-regulation of certain adhesion (CD11a, CD49d), activation (CD69), and costimulatory (CD86) receptors accompany these transcriptional events. Most importantly, recently migrated T cells display a faster rate of migration when reseeded onto an EC monolayer. Finally, T cells become hyperresponsive to antigenic challenge after noncognate interactions with the endothelium. These effects appear not to be due to the selection of preactivated T lymphocytes, because they occur also in clonal T cell populations and appear to be mediated by αLβ2 integrin-CD54 interactions. We conclude that CD4+ memory T cell extravasation is accompanied by phenotypic and functional changes induced by the interactions with the EC, which favor tissue infiltration by T cells and their further activation once they reach the antigenic site.
Intracellular Domains of Target Antigens Influence Their Capacity to Trigger Antibody-Dependent Cell-Mediated Cytotoxicity
Authors: Tiroch Klaus , Stockmeyer Bernhard , Frank Carola , Valerius Thomas
Published: April 2014

Ab-mediated signaling in tumor cells and Ab-dependent cell-mediated cytotoxicity (ADCC) are both considered as relevant effector mechanisms for Abs in tumor therapy. To address potential interactions between these two mechanisms, we generated HER-2/neu- and CD19-derived chimeric target Ags, which were expressed in experimental tumor target cells. HER-2/neu-directed Abs were documented to mediate effective ADCC with both mononuclear cells (MNCs) and polymorphonuclear granulocytes (PMNs), whereas Abs against CD19 were effective only with MNCs and not with PMNs. We generated cDNA encoding HER-2/CD19 or CD19/HER-2 (extracellular/intracellular) chimeric fusion proteins by combining cDNA encoding extracellular domains of HER-2/neu or CD19 with intracellular domains of CD19 or HER-2/neu, respectively. After transfecting wild-type HER-2/neu or chimeric HER-2/CD19 into Raji Burkitt’s lymphoma cells and wild-type CD19 or chimeric CD19/HER-2 into SK-BR-3 breast cancer cells, target cell lines were selected for high membrane expression of transfected Ags. We then investigated the efficacy of tumor cell lysis by PMNs or MNCs with CD19- or HER-2/neu-directed Ab constructs. MNCs triggered effective ADCC against target cells expressing wild-type or chimeric target Ag. As expected, PMNs killed wild-type HER-2/neu-transfected, but not wild-type CD19-transfected target cells. Interestingly, however, PMNs were also effective against chimeric CD19/HER-2-transfected, but not HER-2/CD19-transfected target cells. In conclusion, these results demonstrate that intracellular domains of target Ags contribute substantially to effective Ab-mediated tumor cell killing by PMNs.
Uncoupling of Proliferation and Stat5 Activation in Thymic Stromal Lymphopoietin-Mediated Signal Transduction
Authors: Isaksen Deborah E. , Baumann Heinz , Zhou Baohua , Nivollet Sebastien , Farr Andrew G. , Levin Steven D. , Ziegler Steven F.
Published: April 2014

Thymic stromal lymphopoietin (TSLP) is a cytokine that facilitates B lymphocyte differentiation and costimulates T cells. Previous studies have demonstrated that a functional TSLP receptor complex is a heterodimer consisting of the TSLP receptor and the IL-7R α-chain. TSLP-mediated signaling is unique among members of the cytokine receptor family in that activation of the transcription factor Stat5 occurs without detectable Janus kinase activation. Using a variety of biological systems we demonstrate here that TSLP-mediated Stat5 activation can be uncoupled from proliferation. We also show that the single tyrosine residue in the cytoplasmic domain of the TSLP receptor is critical for TSLP-mediated proliferation, but is dispensable for Stat5 activation. Our data demonstrate that TSLP-mediated Stat5 activation is insufficient for cell proliferation and identifies residues within the TSLP receptor complex required to mediate these downstream events.
Clonal Selection, Clonal Senescence, and Clonal Succession: The Evolution of the T Cell Response to Infection with a Persistent Virus
Authors: Davenport Miles P. , Fazou Chrysoula , McMichael Andrew J. , Callan Margaret F. C.
Published: April 2014

We have analyzed the CD8+ T cell response to EBV and find that a larger primary burst size is associated with proportionally greater decay during the development of memory. Consequently, immunodominance and clonal dominance are less marked in memory than primary responses. An intuitive interpretation of this finding is that there is a limit to the number of cell divisions a T cell clone can undergo, and that the progeny of clones that have expanded massively during a primary immune response are more prone to die as a result of senescence. To test this hypothesis, we have derived a mathematical model of the response of different T cell clones of varying avidity for Ag in the primary and persistent phases of viral infection. When cellular survival and replication are linked to T cell avidity for Ag and Ag dose, then high-avidity T cells dominate both the primary and secondary responses. We then incorporated a limit in the number of cell divisions of individual T cell clones to test whether such a constraint could reproduce the observed association between cell division number and alterations in the contribution of clones to the response to persistent infection. Comparison of the model output with the experimental results obtained from primary and persistent EBV infection suggests that there is indeed a role for cellular senescence in shaping the immune response to persistent infection.
Bob1 (OCA-B/OBF-1) Differential Transactivation of the B Cell-SpecificB29(Igβ) andmb-1(Igα) Promoters
Authors: Malone Cindy Sue , Wall Randolph
Published: April 2014

The B29 (Igβ) and mb-1 (Igα) gene products are B cell-specific essential components of the B cell receptor that are coexpressed at all stages of B cell differentiation, with the exception of plasma cells, which lack mb-1 expression. Transcription of both genes is governed by a similar cassette of interactive transcription factor-binding elements, including octamer motifs, in TATA-less promoters. In this study, we show the B cell-specific B29 gene promoter is transactivated in B and non-B cells by cotransfection with the B cell-specific octamer cofactor gene, Bob1 (OCA-B/OBF-1). The expression of Bob1 is also sufficient to override the silencing effects of the B29 silencer. This indicates that Bob1 plays a critical role in B cell-specific B29 promoter expression. In contrast, coexpression of Bob1 had no effect on mb-1 promoter activity. Bob1 transactivation only occurs with select octamer sequences that have an adenosine at position 5 (ATGCAAAT). The B29 promoter conforms to this consensus octamer motif, while the mb-1 promoter octamer motif does not. Octamer motif swapping between B29 and mb-1 promoters renders B29 unresponsive to Bob1 transactivation and makes mb-1 competent for Bob1 transactivation, thereby indicating that the B29 octamer motif is solely responsible for Bob1 interaction. Additionally, the mb-1 construct containing the B29 octamer motif is expressed in a plasmacytoma cell line, while the wild-type mb-1 promoter is not. Bob1 transactivation of B29 and the lack of this transactivation of mb-1 account for the differential expression of B29 and mb-1 in terminally differentiated plasma cells.
Autocrine Deactivation of Macrophages in Transgenic Mice Constitutively Overexpressing IL-10 Under Control of the Human CD68 Promoter
Authors: Lang Roland , Rutschman Robert L. , Greaves David R. , Murray Peter J.
Published: April 2014

IL-10 plays an essential role in blocking cytokine production by activated macrophages. To analyze the consequences of enforced expression of IL-10 by macrophages on innate and adaptive immune responses, we generated transgenic mice (macIL-10tg mice) expressing an epitope-tagged IL-10 (Flag-IL-10) under control of the human CD68 promoter. Expression of Flag-IL-10 was constitutive and restricted to macrophages, as shown by sorting splenocyte cell populations and intracellular staining for IL-10. Transgenic macrophages displayed suppressed production of TNF-α and IL-12 upon stimulation with LPS. When macIL-10tg mice were challenged with LPS, serum levels of proinflammatory cytokines were attenuated compared with controls. Infection with Mycobacterium bovis bacille Calmette-Guérin resulted in ∼10-fold-higher bacterial loads than in wild-type mice. Normal T and B cell responses were observed in macIL-10tg mice, suggesting that macrophage-specific overexpression of IL-10 predominantly acts in an autocrine/paracrine manner, resulting in chronically deactivated macrophages that manifest an impaired ability to control pathogens.
Increased Survival in Sepsis by In Vivo Adenovirus-Induced Expression of IL-10 in Dendritic Cells
Authors: Oberholzer Andreas , Oberholzer Caroline , Bahjat Keith S. , Ungaro Ricardo , Tannahill Cynthia L. , Murday Michelle , Bahjat Frances R. , Abouhamze Zaher , Tsai Van , LaFace Drake , Hutchins Beth , Moldawer Lyle L. , Clare-Salzler Michael J.
Published: April 2014

The dendritic cell (DC) is the most potent APC of the immune system, capable of stimulating naive T cells to proliferate and differentiate into effector T cells. Recombinant adenovirus (Adv) readily transduces DCs in vitro allowing directed delivery of transgenes that modify DC function and immune responses. In this study we demonstrate that footpad injection of a recombinant Adv readily targets transduction of myeloid and lymphoid DCs in the draining popliteal lymph node, but not in other lymphoid organs. Popliteal DCs transduced with an empty recombinant Adv undergo maturation, as determined by high MHC class II and CD86 expression. However, transduction with vectors expressing human IL-10 limit DC maturation and associated T cell activation in the draining lymph node. The extent of IL-10 expression is dose dependent; transduction with low particle numbers (105) yields only local expression, while transduction with higher particle numbers (107 and 1010) leads additionally to IL-10 appearance in the circulation. Furthermore, local DC expression of human IL-10 following in vivo transduction with low particle numbers (105) significantly improves survival following cecal ligation and puncture, suggesting that compartmental modulation of DC function profoundly alters the sepsis-induced immune response.
The IFN-Inducible Golgi- and Endoplasmic Reticulum- Associated 47-kDa GTPase IIGP Is Transiently Expressed During Listeriosis
Authors: Zerrahn Jens , Schaible Ulrich E. , Brinkmann Volker , Guhlich Ute , Kaufmann Stefan H. E.
Published: April 2014

Members of the 47-kDa GTPase family are implicated in an IFN-γ-induced, as yet unclear, mechanism that confers innate resistance against infection with intracellular pathogens. Overt immunological parameters are apparently uncompromised in mice deficient for individual members and the prototype of this family, IGTP, localizes to the endoplasmic reticulum. This suggests that these GTPases are involved in intracellular defense. We analyzed the expression of the 47-kDa GTPase cognate, IIGP, in splenic sections from mice infected with the intracellular pathogen Listeria monocytogenes by immunohistochemistry. An early transient IIGP induction was observed revealing the IFN-γ responsiveness of cellular subcompartments within the spleen in early listeriosis. Marginal metallophilic macrophages and endothelial cells within the red and white pulp strongly expressed IIGP, while other splenocytes remained negative. In vitro analyses show that both type I and type II IFNs are prime stimuli for IIGP induction in various cells, including L. monocytogenes-infected or LPS-stimulated macrophages, endothelial cells, and activated T cells. Contrary to the subcellular localization of IGTP, IIGP was predominantly associated with the Golgi apparatus and also localizes to the endoplasmic reticulum. We conclude that IIGP exerts a distinct role in IFN-induced intracellular membrane trafficking or processing.
γ3 Gene-Disrupted Mice Selectively Deficient in the Dominant IgG Subclass Made to Bacterial Polysaccharides. II. Increased Susceptibility to Fatal Pneumococcal Sepsis Due to Absence of Anti-Polysaccharide IgG3 Is Corrected by Induction of Anti-Polysaccharide IgG1
Authors: McLay John , Leonard Ethan , Petersen Sheryl , Shapiro David , Greenspan Neil S. , Schreiber John R.
Published: April 2014

Bacterial polysaccharides (PS) are type 2 T-independent Ags that elicit Abs restricted in isotype to IgM and predominantly IgG2 in humans and IgM, and IgG3 in mice. Humans with IgG2 subclass deficiency are susceptible to sinus and pulmonary infections with PS-encapsulated bacteria. We previously developed an IgG3-deficient mouse by disrupting the γ3 H chain constant region gene via targeted mutagenesis. Mutant mice lacking IgG3 were backcrossed for 10 generations to wild-type (WT) BALB/c mice to generate BALB/c mice that have complete absence of IgG3. WT mice immunized with type 3 Streptococcus pneumoniae capsular PS made anti-PS IgM, IgG3, and small quantities of IgG1, which opsonized S. pneumoniae for killing by polymorphonuclear leukocytes. These mice were protected against death from lethal doses of type 3 S. pneumoniae. In contrast, IgG3−/− mice made similar titers of anti-PS IgM and IgG1 as WT mice but no IgG3, and had poorly opsonic sera with significantly increased mortality after S. pneumoniae challenge. Immunization of IgG3−/− mice with type 3 S. pneumoniae PS conjugated to carrier protein CRM197-elicited IgM and high-titer IgG1 Abs, restored serum opsonization, and gave protection from mortality after S. pneumoniae, challenge comparable to WT mice. We conclude that mice lacking the dominant IgG3 subclass made to bacterial PS are more susceptible to fatal S. pneumoniae sepsis than WT mice, but that IgG1 induced by a S. pneumoniae glycoconjugate can adequately protect against S. pneumoniae sepsis. This model suggests that IgG subclass of anti-PS Ab is an important component of immunity to encapsulated bacteria.
Plasmodium falciparum Variant Surface Antigen Expression Varies Between Isolates Causing Severe and Nonsevere Malaria and Is Modified by Acquired Immunity
Authors: Nielsen Morten A. , Staalsoe Trine , Kurtzhals Jørgen A. L. , Goka Bamenla Q. , Dodoo Daniel , Alifrangis Michael , Theander Thor G. , Akanmori Bartholomew D. , Hviid Lars
Published: April 2014

In areas of endemic parasite transmission, protective immunity to Plasmodium falciparum malaria is acquired over several years with numerous disease episodes. Acquisition of Abs to parasite-encoded variant surface Ags (VSA) on the infected erythrocyte membrane is important in the development of immunity, as disease-causing parasites appear to be those not controlled by preexisting VSA-specific Abs. In this work we report that VSA expressed by parasites from young Ghanaian children with P. falciparum malaria were commonly and strongly recognized by plasma Abs from healthy children in the same area, whereas recognition of VSA expressed by parasites from older children was weaker and less frequent. Independent of this, parasites isolated from children with severe malaria (cerebral malaria and severe anemia) were better recognized by VSA-specific plasma Abs than parasites obtained from children with nonsevere disease. This was not due to a higher infection multiplicity in younger patients or in patients with severe disease. Our data suggest that acquisition of VSA-specific Ab responses gradually restricts the VSA repertoire that is compatible with parasite survival in the semi-immune host. This appears to limit the risk of severe disease by discriminating against the expression of VSA likely to cause life-threatening complications, such as cerebral malaria and severe anemia. Such VSA seem to be preferred by parasites infecting a nonimmune host, suggesting that VSA expression and switching are not random, and that the VSA expression pattern is modulated by immunity. This opens the possibility of developing morbidity-reducing vaccines targeting a limited subset of common and particularly virulent VSA.
The NKp46 Receptor Contributes to NK Cell Lysis of Mononuclear Phagocytes Infected with an Intracellular Bacterium
Authors: Vankayalapati Ramakrishna , Wizel Benjamin , Weis Stephen E. , Safi Hassan , Lakey David L. , Mandelboim Ofer , Samten Buka , Porgador Angel , Barnes Peter F.
Published: April 2014

We used human tuberculosis as a model to investigate the role of NK cytotoxic mechanisms in the immune response to intracellular infection. Freshly isolated NK cells and NK cell lines from healthy donors lysed Mycobacterium tuberculosis-infected monocytes to a greater extent than uninfected monocytes. Lysis of infected monocytes was associated with increased expression of mRNA for the NKp46 receptor, but not the NKp44 receptor. Antisera to NKp46 markedly inhibited lysis of infected monocytes. NK cell-mediated lysis was not due to reduced expression of MHC class I molecules on the surface of infected monocytes or to enhanced production of IL-18 or IFN-γ. NK cell lytic activity against M. tuberculosis-infected monocytes and NKp46 mRNA expression were reduced in tuberculosis patients with ineffective immunity to M. tuberculosis compared with findings in healthy donors. These observations suggest that 1) the NKp46 receptor participates in NK cell-mediated lysis of cells infected with an intracellular pathogen, and 2) the reduced functional capacity of NK cells is associated with severe manifestations of infectious disease.
Iron Chelation Via Deferoxamine Exacerbates Experimental Salmonellosis Via Inhibition of the Nicotinamide Adenine Dinucleotide Phosphate Oxidase-Dependent Respiratory Burst
Authors: Collins Helen L. , Kaufmann Stefan H. E. , Schaible Ulrich E.
Published: April 2014

Competition for cellular iron (Fe) is a vital component of the interaction between host and intracellular pathogen. The host cell requires Fe for the execution of antimicrobial effector mechanisms, whereas most bacteria have an obligate requirement for Fe to sustain growth and intracellular survival. In this study, we show that chelation of host Fe in vivo exacerbates murine salmonellosis, resulting in increased bacterial load and decreased survival times. We further demonstrate that host Fe deprivation results in an inability to induce the NADPH oxidase-dependent production of reactive oxygen, an essential host defense mechanism for the early control of Salmonella typhimurium infection. Thus, altering the equilibrium of intracellular Fe influences the course of infection to the benefit of the pathogen.
Gq Signaling Is Required for Allergen-Induced Pulmonary Eosinophilia
Authors: Borchers Michael T. , Justice Paul J. , Ansay Tracy , Mancino Valeria , McGarry Michael P. , Crosby Jeffrey , Simon Melvin I. , Lee Nancy A. , Lee James J.
Published: April 2014

The complexity and magnitude of interactions leading to the selective infiltration of eosinophils in response to inhaled allergens are formidable obstacles to a larger understanding of the pulmonary pathology associated with allergic asthma. This study uses knockout mice to demonstrate a novel function for the heterotrimeric G protein, Gq, in the regulation of pulmonary eosinophil recruitment. In the absence of Gq signaling, eosinophils failed to accumulate in the lungs following allergen challenge. These studies demonstrate that the inhibition of eosinophil accumulation in the airways is attributed to the failure of hemopoietically derived cells to elaborate GM-CSF in the airways. The data suggest that activation of a Gq-coupled receptor(s) on resident leukocytes in the lung elicits expression of GM-CSF, which, in turn, is required for allergen-induced pulmonary eosinophilia, identifying a novel pathway of eosinophil-associated effector functions leading to pulmonary pathology in diseases such as asthma.
Tissue-Specific Mechanisms Control the Retention of IL-8 in Lungs and Skin
Authors: Frevert Charles W. , Goodman Richard B. , Kinsella Michael G. , Kajikawa Osamu , Ballman Kimberly , Clark-Lewis Ian , Proudfoot Amanda E. I. , Wells Timothy N. C. , Martin Thomas R.
Published: April 2014

Chemokines are a group of structurally related peptides that promote the directed migration of leukocytes in tissue. Mechanisms controlling the retention of chemokines in tissue are not well understood. In this study we present evidence that two different mechanisms control the persistence of the CXC chemokine, IL-8, in lungs and skin. 125I-labeled IL-8 was injected into the airspaces of the lungs and the dermis of the skin and the amount of 125I-labeled IL-8 that remained at specified times was measured by scintillation counting. The 125I-labeled IL-8 was cleared much more rapidly from skin than lungs, as only 2% of the 125I-labeled IL-8 remained in skin at 4 h whereas 50% of the 125I-labeled IL-8 remained in lungs at 4 h. Studies in neutropenic rabbits showed that neutrophils shortened the retention of 125I-labeled IL-8 in skin but not lungs. A monomeric form of IL-8, N-methyl-leucine 25 IL-8, was not retained as long in lungs as recombinant human IL-8, indicating that dimerization of IL-8 is a mechanism that increases the local concentration and prolongs the retention of 125I-labeled IL-8 in lungs. These observations show that the mechanisms that control the retention of IL-8 in tissue include neutrophil migration and dimerization, and that the importance of these varies in different tissues.