bluuebunny/crossref_metadata_2025 huggingface dataset:
A Critical Role of Fc Receptor-Mediated Antibody-Dependent Phagocytosis in the Host Resistance to Blood-Stage Plasmodium berghei XAT Infection
Authors: Yoneto Toshihiko , Waki Seiji , Takai Toshihiro , Tagawa Yoh-ichi , Iwakura Yoichiro , Mizuguchi Junichiro , Nariuchi Hideo , Yoshimoto Takayuki
Published: April 2014

Plasmodium berghei XAT is an irradiation-induced attenuated variant derived from the lethal strain P. berghei NK65, and its blood-stage parasites are spontaneously cleared in immune competent mice. In the present study, we studied the mechanism of host resistance to blood-stage malaria infection using P. berghei XAT. Infection enhanced Ab-dependent phagocytosis of PRBC by splenic macrophages in wild-type C57BL/6 mice. In contrast, FcR γ-chain knockout (FcRγ−/−) mice, which lack the ability to mediate Ab-dependent phagocytosis and Ab-dependent cell-mediated cytotoxicity through FcγRI, FcγRII, and FcγRIII, could not induce Ab-dependent phagocytic activity. These FcRγ−/− mice showed increased susceptibility to the P. berghei XAT infection, with eventually fatal results, although they produced comparable amounts of IFN-γ by spleen cells and anti-XAT Abs in serum. In addition, passive transfer of anti-XAT IgG obtained from wild-type mice that had recovered from infection into FcRγ−/− mice could not suppress the increase in parasitemia, and almost all of these mice died after marked parasitemia. In contrast, passive transfer of anti-XAT IgG into control wild-type mice inhibited the increase in parasitemia. IFN-γ−/− mice, which were highly susceptible to the P. berghei XAT infection, failed to induce Ab-dependent phagocytic activity and also showed reduced production of serum anti-XAT IgG2a isotype compared with control wild-type mice. These results suggest that FcR-mediated Ab-dependent phagocytosis, which is located downstream of IFN-γ production, is important as an effector mechanism to eliminate PRBC in blood-stage P. berghei XAT infection.
Secretory IgA Specific for a Conserved Epitope on gp41 Envelope Glycoprotein Inhibits Epithelial Transcytosis of HIV-1
Authors: Alfsen Annette , Iniguez Pierre , Bouguyon Edwige , Bomsel Morgane
Published: April 2014

As one of the initial mucosal transmission pathways of HIV (HIV-1), epithelial cells translocate HIV-1 from apical to basolateral surface by nondegradative transcytosis. Transcytosis is initiated when HIV-1 envelope glycoproteins bind to the epithelial cell membrane. Here we show that the transmembrane gp41 subunit of the viral envelope binds to the epithelial glycosphingolipid galactosyl ceramide (Gal Cer), an alternative receptor for HIV-1, at a site involving the conserved ELDKWA epitope. Disrupting the raft organization of the Gal Cer-containing microdomains at the apical surface inhibited HIV-1 transcytosis. Immunological studies confirmed the critical role of the conserved ELDKWA hexapeptide in HIV-1 transcytosis. Mucosal IgA, but not IgG, from seropositive subjects targeted the conserved peptide, neutralized gp41 binding to Gal Cer, and blocked HIV-1 transcytosis. These results underscore the important role of secretory IgA in designing strategies for mucosal protection against HIV-1 infection.
A Potential Role for Annexin 1 as a Physiologic Mediator of Glucocorticoid-Induced L-Selectin Shedding from Myeloid Cells
Authors: Strausbaugh Holly J. , Rosen Steven D.
Published: April 2014

Glucocorticoids can dampen inflammatory responses by inhibiting neutrophil recruitment to tissue sites. The detailed mechanism by which glucocorticoids exert this affect on neutrophils is unknown. L-selectin is a leukocyte cell surface receptor that is implicated in several steps of neutrophil recruitment. Recently, several studies have shown that systemic treatment of animals and humans with glucocorticoids induces decreased L-selectin expression on neutrophils, suggesting one mechanism by which inflammation may be negatively regulated. However, when neutrophils are treated in vitro with glucocorticoids, no effect on L-selectin expression is observed. Thus, the existence of an additional mediator is plausible. In this study, we investigate whether annexin 1 (ANX1), a recognized second messenger of glucocorticoids, could be such a mediator. We show that ANX1 induces a dose- and time-dependent decrease in L-selectin expression on both peripheral blood neutrophils and monocytes but has no effect on lymphocytes. The loss of L-selectin from neutrophils is due to shedding that is mediated by a cell surface metalloprotease (“sheddase”). Using cell shape and a β2 integrin activation epitope, we show that the ANX1-induced shedding of L-selectin appears to occur without overt cell activation. These data may provide the basis for further understanding of mechanisms involved in the down-regulation of inflammatory responses.
Phosphorylation of the Activation Loop of γ p21-Activated Kinase (γ-Pak) and Related Kinases (MSTs) in Normal and Stressed Neutrophils
Authors: Lian Jian P. , Toker Alex , Badwey John A.
Published: April 2014

Neutrophils stimulated with a variety of chemoattractants exhibit a rapid activation of two p21-activated kinases (Paks) with molecular masses of ∼63 and 69 kDa (γ- and α-Pak). A number of in vitro studies suggest that modification of Thr402 in the activation loop (AL) of γ-Pak can play a critical role in the regulation of this kinase under certain circumstances. A phosphospecific Ab was generated to this region of Pak (pPak(AL)Ab). This Ab reacted with activated γ- and α-Pak from fMLP-stimulated neutrophils that contain the sequence KRXT(P)XXGTP in their ALs. The rapid but transient activation of Paks in normal stimulated neutrophils coincided with phosphorylation and dephosphorylation at the ALs of these enzymes. In contrast, stressed cells exhibited a prolonged phosphorylation at Thr402 in both intact γ-Pak and a proteolytic fragment of this kinase. The pPak(AL)Ab also reacted with the mammalian sterile twenty-like kinases (MSTs) (members of the Pak family) in osmotically stressed neutrophils and neutrophils treated with certain apoptotic agents (i.e., tumor promoters that inhibit type 1 and 2A protein phosphatases) but not in normal fMLP-stimulated cells. Thus, our results indicate that the AL of γ-Pak undergoes transient phosphorylation during normal neutrophil stimulation and chronic phosphorylation in stressed cells. In addition, we demonstrate that a number of MSTs are present in neutrophils and also undergo phosphorylation during stressful circumstances.
IL-18 Gene Transfer by Adenovirus Prevents the Development of and Reverses Established Allergen-Induced Airway Hyperreactivity
Authors: Walter David M. , Wong Carmen P. , DeKruyff Rosemarie H. , Berry Gerald J. , Levy Shoshana , Umetsu Dale T.
Published: April 2014

We examined the role of IL-18 in preventing the development of and in reversing established allergen-induced airway inflammation and airway hyperreactivity (AHR), the cardinal features of asthma. IL-18, which potently induces IFN-γ, was administered into the respiratory tract as cDNA in a replication-deficient adenovirus (Adv). Treatment of OVA-sensitized mice with the IL-18-expressing Adv reduced allergen-specific IL-4 production, airway eosinophilia, and mucus production, increased IFN-γ production, and prevented the development of AHR. The effects of the IL-18 Adv treatment were dependent on the presence of IFN-γ and IL-12. Moreover, administration of the IL-18 Adv to mice with established AHR greatly reduced AHR and IL-4 production and increased IFN-γ production. These results demonstrate that IL-18, when administered by Adv into the respiratory tract, effectively reduces AHR and replaces an established Th2-biased immune response with a Th1-biased response.
A Novel Serum Protein That Is Selectively Produced by Cytotoxic Lymphocytes
Authors: Ogawa Kazuyuki , Tanaka Kazuya , Ishii Akira , Nakamura Yoshiko , Kondo Shigemi , Sugamura Kazuo , Takano Shoichi , Nakamura Masataka , Nagata Kinya
Published: April 2014

Cytotoxic lymphocytes such as CTL and NK cells play principal roles in the host defense mechanisms. Monitoring these effector cells in vivo is helpful to understand the immune responses in disorders such as cancer and infectious diseases. In this study, we identified a novel secretory protein, killer-specific secretory protein of 37 kDa (Ksp37), as a Th1-specific protein by a subtractive cloning method between human Th1 and Th2 cells. In peripheral blood leukocytes, Ksp37 expression was limited to Th1-type CD4+ T cells, effector CD8+ T cells, γδ T cells, and CD16+ NK cells. Most of these Ksp37-expressing cells coexpressed perforin, indicating that Ksp37 is selectively and commonly expressed in the lymphocytes that have cytotoxic potential. Ksp37 was released at constant rate from both unstimulated and stimulated PBMCs in vitro and also detected in normal human sera. In healthy individuals, serum Ksp37 levels were significantly higher in children (mean ± SD; 984 ± 365 ng/ml for age 0–9) than in adults (441 ± 135 ng/ml for age 20–99), consistent with reported differences in the absolute counts of blood T and NK cells between children and adults. In patients with infectious mononucleosis, transient elevation of serum Ksp37 levels was observed during the early acute phase of primary EBV infection. These results suggest that Ksp37 may be involved in an essential process of cytotoxic lymphocyte-mediated immunity and that Ksp37 may also have clinical value as a new type of serum indicator for monitoring cytotoxic lymphocytes in vivo.
Calreticulin, a Potential Cell Surface Receptor Involved in Cell Penetration of Anti-DNA Antibodies
Authors: Seddiki Nabila , Nato Farida , Lafaye Pierre , Amoura Zahir , Piette Jean Charles , Mazié Jean Claude
Published: April 2014

A 50-kDa protein was purified as a potential receptor, using an affinity matrix containing biotinylated F14.6 or H9.3 anti-DNA mAbs derived from autoimmune (New Zealand Black × New Zealand White)F1 mouse and membrane extracts from cells. This protein was identified as calreticulin (CRT) by microsequencing. Confocal microscopy and FACS analysis showed that CRT was present on the surface of various cells. CRT protein was recognized by a panel of anti-DNA mAbs in ELISA. The binding of F14.6 to lymphocytes and Chinese hamster ovary cells was inhibited by soluble CRT or SPA-600. Thus, the anti-DNA mAbs used in this study bound to CRT, suggesting that CRT may mediate their penetration into the cells and play an important role in lupus pathogenesis.
LFA-1-Mediated Costimulation of CD8+ T Cell Proliferation Requires Phosphatidylinositol 3-Kinase Activity
Authors: Ni Hsiao-Tzu , Deeths Matthew J. , Mescher Matthew F.
Published: April 2014

LFA-1 binding to ICAM-I provides a costimulatory signal for CD8+ T cell activation that results in increased IL-2 mRNA levels and protein production to support proliferation. CD28 binding to its B7 ligands has the same effect, and the two costimulatory receptors activate some of the same intracellular signaling events, including up-regulation of phosphatidylinositol (PI) 3-kinase activity. However, costimulation by LFA-1 depends upon the activity of this enzyme, whereas costimulation by CD28 does not, as evidenced by differential effects of specific inhibitors of PI 3-kinase. When cells are costimulated with ICAM-1 in the presence of the inhibitors wortmannin or LY294002, proliferation is blocked, but increases in IL-2 mRNA levels and protein production are not. Costimulation also results in increased surface expression of CD25, which is essential for formation of an active IL-2R. This is blocked by the PI 3-kinase inhibitors when costimulation is via LFA-1 but not when it is via CD28. Finally, IL-2-driven proliferation is not blocked by the inhibitors once CD25 surface expression has increased. Thus, the PI 3-kinase-dependent step in CD8 T cell costimulation by LFA-1 is up-regulation of IL-2R expression. In contrast, CD28 engagement also increases IL-2R surface expression, but the up-regulation does not depend upon PI 3-kinase activity.
MHC Class I-Ly49 Interactions Shape the Ly49 Repertoire on Murine NK Cells
Authors: Fahlén Linda , Lendahl Urban , Sentman Charles L.
Published: April 2014

This study aims to determine how the interaction of Ly49 receptors with MHC class I molecules shapes the development of the Ly49 repertoire. We have examined the percentage of NK cells that expressed Ly49A, Ly49G2, and Ly49D in single and double Ly49A/C-transgenic mice on four different MHC backgrounds, H-2b, H-2d, H-2b/d, and β2-microglobulin−/−. The results show that the total numbers of NK cells were not different among the strains. The prior expression of a Ly49 receptor capable of binding to self MHC class I altered the percentage of NK cells expressing endogenous Ly49A, Ly49G2, and Ly49D even in mice in which no MHC ligand was present for the latter receptors. The NK cells in the Ly49-transgenic mice expressed the same level of endogenous Ly49 receptors as wild-type mice of a similar MHC background. In contrast, the number of NK T cells was reduced in mice in which the Ly49 transgene could bind to a MHC class I molecule. The onset of Ly49 receptor expression on NK cells during ontogeny was not altered in the presence of transgenic Ly49 receptors. These data support a sequential model and argue against a selection model for Ly49 repertoire development on NK cells.
T Cells Enhance Production of IL-18 by Monocytes in Response to an Intracellular Pathogen
Authors: Vankayalapati Ramakrishna , Wizel Benjamin , Lakey David L. , Zhang Yueru , Coffee Keith A. , Griffith David E. , Barnes Peter F.
Published: April 2014

We studied the effect of T cells on IL-18 production by human monocytes in response to Mycobacterium tuberculosis. Addition of activated T cells markedly enhanced IL-18 production by monocytes exposed to M. tuberculosis. This effect was mediated by a soluble factor and did not require cell-to-cell contact. The effect of activated T cells was mimicked by recombinant IFN-γ and was abrogated by neutralizing Abs to IFN-γ. IFN-γ also enhanced the capacity of alveolar macrophages to produce IL-18 in response to M. tuberculosis, suggesting that this mechanism also operates in the lung during mycobacterial infection. IFN-γ increased IL-18 production by increasing cleavage of pro-IL-18 to mature IL-18, as it enhanced caspase-1 activity but did not increase IL-18 mRNA expression. These findings suggest that activated T cells can contribute to the initial immune response by augmenting IL-18 production by monocytes in response to an intracellular pathogen.
Innate Immunity to Viruses: Control of Vaccinia Virus Infection by γδ T Cells
Authors: Selin Liisa K. , Santolucito Paul A. , Pinto Amelia K. , Szomolanyi-Tsuda Eva , Welsh Raymond M.
Published: April 2014

The existence of γδ T cells has been known for over 15 years, but their significance in innate immunity to virus infections has not been determined. We show here that γδ T cells are well suited to provide a rapid response to virus infection and demonstrate their role in innate resistance to vaccinia virus (VV) infection in both normal C57BL/6 and β TCR knockout (KO) mice. VV-infected mice deficient in γδ T cells had significantly higher VV titers early postinfection (PI) and increased mortality when compared with control mice. There was a rapid and profound VV-induced increase in IFN-γ-producing γδ T cells in the peritoneal cavity and spleen of VV-infected mice beginning as early as day 2 PI. This rapid response occurred in the absence of priming, as there was constitutively a significant frequency of VV-specific γδ T cells in the spleen in uninfected β TCR KO mice, as demonstrated by limiting dilution assay. Also, like NK cells, another mediator of innate immunity to viruses, γδ T cells in uninfected β TCR KO mice expressed constitutive cytolytic activity. This cytotoxicity was enhanced and included a broader range of targets after VV infection. VV-infected β TCR KO mice cleared most of the virus by day 8 PI, the peak of the γδ T cell response, but thereafter the γδ T cell number declined and the virus recrudesced. Thus, γδ T cells can be mediators of innate immunity to viruses, having a significant impact on virus replication early in infection in the presence or absence of the adaptive immune response.
New Insights Into Endotoxin-Induced Activation of Macrophages: Involvement of a K+ Channel in Transmembrane Signaling
Authors: Blunck Rikard , Scheel Olaf , Müller Mareike , Brandenburg Klaus , Seitzer Ulrike , Seydel Ulrich
Published: April 2014

LPS (endotoxins) activate cells of the human immune system, among which are monocytes and macrophages, to produce endogenous mediators. These regulate the immune response, but may also cause severe harm leading to septic shock. The activation of monocytes/macrophages by LPS is mediated by a membrane-bound LPS receptor, mCD14. As mCD14 lacks a transmembrane domain, a further protein is required for the signal transducing step to the cell interior. Here we show, using excised outside-out membrane patches, that activation of a high-conductance Ca2+- and voltage-dependent potassium channel is an early step in the transmembrane signal transduction in macrophages. The channel is activated by endotoxically active LPS in a dose-dependent manner. Channel activation can be completely inhibited by LPS antagonists and by anti-CD14 Abs. Activation of the channel is essential for LPS-induced cytokine production as shown by its inhibition by selective K+ channel blockers.
A Cryptococcal Capsular Polysaccharide Mimotope Prolongs the Survival of Mice withCryptococcus neoformansInfection
Authors: Fleuridor Richardson , Lees Andrew , Pirofski Liise-anne
Published: April 2014

Defined Abs to the Cryptococcus neoformans capsular polysaccharide glucuronoxylomannan (GXM) have been shown to be protective against experimental cryptococcosis. This suggests that if a vaccine could induce similar Abs it might protect against infection. However, the potential use of a GXM-based vaccine has been limited by evidence that GXM is a poor immunogen that can induce nonprotective and deleterious, as well as protective, Abs, and that the nature of GXM oligosaccharide epitopes that can elicit a protective response is unknown. In this study, we investigated whether a peptide surrogate for a GXM epitope could induce an Ab response to GXM in mice. The immunogenicity of peptide-protein conjugates produced by linking a peptide mimetic of GXM, P13, to either BSA, P13-BSA, or tetanus toxoid, P13-tetanus toxoid, was examined in BALB/c and CBA/n mice that received four s.c. injections of the conjugates at 14- to 30-day intervals. All mice immunized with conjugate produced IgM and IgG to P13 and GXM. Challenge of conjugate-immunized mice with C. neoformans revealed longer survival and lower serum GXM levels than control mice. These results indicate that 1) P13 is a GXM mimotope and 2) that it induced a protective response against C. neoformans in mice. P13 is the first reported mimotope of a C. neoformans Ag. Therefore, the P13 conjugates are vaccine candidates for C. neoformans and their efficacy in this study suggests that peptide mimotopes selected by protective Abs deserve further consideration as vaccine candidates for encapsulated pathogens.
Bystander Activation of CD8+ T Cells Contributes to the Rapid Production of IFN-γ in Response to Bacterial Pathogens
Authors: Lertmemongkolchai Ganjana , Cai Guifang , Hunter Christopher A. , Bancroft Gregory J.
Published: April 2014

The bacterium Burkholderia pseudomallei causes a life-threatening disease called melioidosis. In vivo experiments in mice have identified that a rapid IFN-γ response is essential for host survival. To identify the cellular sources of IFN-γ, spleen cells from uninfected mice were stimulated with B. pseudomallei in vitro and assayed by ELISA and flow cytometry. Costaining for intracellular IFN-γ vs cell surface markers demonstrated that NK cells and, more surprisingly, CD8+ T cells were the dominant sources of IFN-γ. IFN-γ+ NK cells were detectable after 5 h and IFN-γ+ CD8+ T cells within 15 h after addition of bacteria. IFN-γ production by both cell populations was inhibited by coincubation with neutralizing mAb to IL-12 or IL-18, while a mAb to TNF had much less effect. Three-color flow cytometry showed that IFN-γ-producing CD8+ T cells were of the CD44high phenotype. The preferential activation of NK cells and CD8+ T cells, rather than CD4+ T cells, was also observed in response to Listeria monocytogenes or a combination of IL-12 and IL-18 both in vitro and in vivo. This rapid mechanism of CD8+ T cell activation may be an important component of innate immunity to intracellular pathogens.
Variable Immunodominance Hierarchies for H2-M3-RestrictedN-Formyl Peptides Following Bacterial Infection
Authors: Kerksiek Kristen M. , Busch Dirk H. , Pamer Eric G.
Published: April 2014

H2-M3-restricted presentation of N-formyl methionine (f-Met) peptides to CD8+ T cells provides a mechanism for selective recognition of bacterial infection. In this report we demonstrate that Listeria monocytogenes infection induces distinct CD8+ T cell populations specific for each of the known Listeria-derived formyl methionine peptides presented by M3. The sum H2-M3-restricted, Listeria-specific T cell response constitutes a major fraction of the total CD8+ T cell response to primary infection. H2-M3-restricted T cell populations expand synchronously in vivo and achieve peak frequencies ∼2 days earlier than MHC class Ia-restricted T cell populations. Although cross-recognition of different f-Met peptides by M3-restricted T cells was previously described, costaining of CD8+ T cells ex vivo with H2-M3 tetramers complexed with different f-Met peptides shows that the majority of Listeria-specific, M3-restricted CD8+ T cells are peptide specific. In contrast to the highly predictable size and immunodominance hierarchies of MHC class Ia-restricted T cell responses, the magnitudes of T cell responses specific for H2-M3-restricted peptides are remarkably variable between genetically identical mice. Our findings demonstrate that H2-M3-restricted T cell responses are distinct from classically restricted T cell responses to bacterial infection.
The Role of IL-10 in Promoting Disease Progression in Leishmaniasis
Authors: Kane Margaret Mentink , Mosser David M.
Published: April 2014

To determine the role of IL-10 in cutaneous leishmaniasis, we examined lesion development following Leishmania major infection of genetically susceptible BALB/c mice lacking IL-10. Whereas normal BALB/c mice developed progressive nonhealing lesions with numerous parasites within them, IL-10−/− BALB/c mice controlled disease progression, and had relatively small lesions with 1000-fold fewer parasites within them by the fifth week of infection. We also examined a mechanism whereby Leishmania induced the production of IL-10 from macrophages. We show that surface IgG on Leishmania amastigotes allows them to ligate Fcγ receptors on inflammatory macrophages to preferentially induce the production of high amounts of IL-10. The IL-10 produced by infected macrophages prevented macrophage activation and diminished their production of IL-12 and TNF-α. In vitro survival assays confirmed the importance of IL-10 in preventing parasite killing by activated macrophages. Pretreatment of monolayers with either rIL-10 or supernatants from amastigote-infected macrophages resulted in a dramatic enhancement in parasite intracellular survival. These studies indicate that amastigotes of Leishmania use an unusual and unexpected virulence factor, host IgG. This IgG allows amastigotes to exploit the antiinflammatory effects of FcγR ligation to induce the production of IL-10, which renders macrophages refractory to the activating effects of IFN-γ.
Flagellin, a Novel Mediator of Salmonella-Induced Epithelial Activation and Systemic Inflammation: IκBα Degradation, Induction of Nitric Oxide Synthase, Induction of Proinflammatory Mediators, and Cardiovascular Dysfunction
Authors: Eaves-Pyles Tonyia , Murthy Kanneganti , Liaudet Lucas , Virág László , Ross Gary , Soriano Francisco Garcia , Szabó Csaba , Salzman Andrew L.
Published: April 2014

Gram-negative sepsis is mediated by the actions of proinflammatory genes induced in response to microbes and their products. We report that flagellin, the monomeric subunit of flagella, is a potent proinflammatory species released by Salmonella. Flagellin (1 μg/ml) induces IκBα degradation, NF-κB nuclear translocation, and inducible NO synthase expression in cultured intestinal epithelial cells (IEC). Aflagellic Salmonella mutants do not induce NF-κB activation or NO production by cultured IEC. Antiserum to flagellin blocks NO production in IEC induced by medium conditioned by a variety of motile Gram-negative enteric pathogens (Escherichia coli, Salmonella muenchen, Serratia marcescens, Proteus mirabilis, and Proteus vulgaris). Flagellin, when injected systemically (∼10 μg/mouse), induces systemic inflammation characterized by the systemic expression of a range of proinflammatory cytokines and chemokines and of inducible NO synthase. At higher doses (∼300 μg/mouse), flagellin induces shock, characterized by hypotension, reduced vascular contractility in mice, and death. The effects of flagellin do not diminish in C3H/HeJ LPS-resistant mice, indicating that the Toll-like receptor-4 receptor is not involved in flagellin’s actions. In LPS-resistant mice, i.p. injection of S. dublin flagellin or medium conditioned by wild-type S. dublin induces serum IFN-γ and TNF-α, whereas medium conditioned by aflagellic mutants has no effect. Flagellin can be detected in the blood of rats with septic shock induced by live bacteria at approximately 1 μg/ml. We propose that flagellin released by Gram-negative pathogens may contribute to the inflammatory response by an LPS- and Toll-like receptor-4-independent pathway.
Search for the Autoantibody Immunodominant Region on Thyroid Peroxidase: Epitopic Footprinting with a Human Monoclonal Autoantibody Locates a Facet on the Native Antigen Containing a Highly Conformational Epitope
Authors: Guo Jin , Yan Xin-Min , McLachlan Sandra M. , Rapoport Basil
Published: April 2014

Autoantibodies to thyroid peroxidase (TPO) are the hallmark of the humoral autoimmune response in human autoimmune thyroiditis (Hashimoto’s thyroiditis). The majority of TPO autoantibodies in individual patients’ sera interact with a restricted immunodominant region on TPO. Although this region can be mapped, previous studies have failed to localize its position on the TPO molecule. We, therefore, used a footprinting approach that can localize a highly conformational, discontinuous epitope on a very large molecule. Extensive biotinylation (∼15 biotins/molecule protein) of lysine residues on the surface of purified, native TPO resulted in loss of multiple tryptic cleavage sites, as determined by analysis of tryptic polypeptide fragments on reverse-phase HPLC. TPO was then complexed with a monoclonal human autoantibody Fab (TR1.9) before biotinylation. After dissociation from TR1.9, TPO was recovered by gel filtration. A trypsin site, previously observed to be lost after TPO biotinylation, was restored when biotinylation was performed on the TPO-TR1.9 complex. The epitope-protected lysine (K) was present in a 30-aa TPO fragment that, by N-terminal sequencing, was found to be K713. Altered recognition by TR1.9 of a TPO-myeloperoxidase chimeric molecule involving this region supported the epitope protection data. In conclusion, we provide the first identification of an amino acid residue (K713) comprising part of an epitope within the TPO immunodominant region. This focal residue localizes the facet on the large, highly complex TPO molecule that contains the immunodominant region and provides the basis for rational guided mutagenesis studies to more fully characterize this region.
Oligoclonal IgA Response in the Vascular Wall in Acute Kawasaki Disease
Authors: Rowley Anne H. , Shulman Stanford T. , Spike Benjamin T. , Mask Carrie A. , Baker Susan C.
Published: April 2014

Kawasaki Disease (KD) is a potentially fatal acute vasculitis of childhood. Although KD is the leading cause of acquired heart disease in children in developed nations, its pathogenesis remains unknown. We previously reported the novel observation that IgA plasma cells infiltrate the vascular wall in acute KD. We have now examined the clonality of this IgA response in vascular tissue from three fatal cases of KD to determine whether it is oligoclonal, suggesting an Ag-driven process, or polyclonal, suggesting nonspecific B cell activation or a response to a superantigen. We first sequenced VDJ junctions of 44 α genes isolated from a primary, unamplified KD vascular cDNA library. Five sets of clonally related α sequences were identified, comprising 34% (15 of 44) of the isolated α sequences. Furthermore, point mutations consistent with somatic mutation were detected in the related sequences. Next, using formalin-fixed coronary arteries from two additional fatal KD cases, we sequenced VDJ junctions of α genes isolated by RT-PCR, and a restricted pattern of CDR3 usage was observed in both. We conclude that the vascular IgA response in acute KD is oligoclonal. The identification of an oligoclonal IgA response in KD strongly suggests that the immune response to this important childhood illness is Ag-driven.
The Restricted Expression of Granzyme M in Human Lymphocytes
Authors: Sayers Thomas J. , Brooks Alan D. , Ward Jerrold M. , Hoshino Tomoaki , Bere William E. , Wiegand Gordon W. , Kelley Janice M. , Smyth Mark J.
Published: April 2014

We have analyzed the expression of human granzyme M (Gzm M) in various human leukocyte subsets using the specific mAb 4H10. Using FACS and Western blotting analysis we compared the expression of Gzm M with that of other granzymes (Gzm A and Gzm B) and the lytic protein perforin. Human Gzm M was constitutively highly expressed in NK cells as was perforin and Gzm A. Surprisingly, freshly isolated NK cells had very low (sometimes undetectable) levels of Gzm B. In contrast to Gzm B and perforin, Gzm M was not detected in highly purified CD4+ and CD8+ T cells either constitutively or after short term activation in vitro. However, low levels of Gzm M were observed in some T cell clones on prolonged passage in vitro. Gzm M was not detected in highly purified neutrophils, monocytes, or tumor cells of the myelomonocytic lineage. Examination of minor T cell subsets from human peripheral blood showed detectable Gzm M in CD3+, CD56+ T cells and γδ T cells. A histological staining procedure was developed that demonstrated a granular staining pattern for Gzm M and a cellular distribution similar to that observed by Western blotting. These data indicate that the expression of Gzm M does not always correlate with the lytic activity of cytotoxic cells. However, expression of Gzm M in NK cells, CD3+, CD56+ T cells, and γδ T cells suggests that this enzyme may play some role in innate immune responses.
CD99 Regulates the Transport of MHC Class I Molecules from the Golgi Complex to the Cell Surface
Authors: Sohn Hae Won , Shin Young Kee , Lee Im-Soon , Bae Young Mee , Suh Young Ho , Kim Min Kyung , Kim Tae Jin , Jung Kyeong Cheon , Park Weon Seo , Park Chan-Sik , Chung Doo Hyun , Ahn Kwangseog , Kim In Sun , Ko Young Hyeh , Bang Yung Jue , Kim Chul Woo , Park Seong Hoe
Published: April 2014

The down-regulation of surface expression of MHC class I molecules has recently been reported in the CD99-deficient lymphoblastoid B cell line displaying the characteristics of Hodgkin’s and Reed-Sternberg phenotype. Here, we demonstrate that the reduction of MHC class I molecules on the cell surface is primarily due to a defect in the transport from the Golgi complex to the plasma membrane. Loss of CD99 did not affect the steady-state expression levels of mRNA and protein of MHC class I molecules. In addition, the assembly of MHC class I molecules and the transport from the endoplasmic reticulum to the cis-Golgi occurred normally in the CD99-deficient cells, and no difference was detected between the CD99-deficient and the control cells in the pattern and degree of endocytosis. Instead, the CD99-deficient cells displayed the delayed transport of newly synthesized MHC class I molecules to the plasma membrane, thus causing accumulation of the molecules within the cells. The accumulated MHC class I molecules in the CD99-deficient cells were colocalized with α-mannosidase II and γ-adaptin in the Golgi compartment. These results suggest that CD99 may be associated with the post-Golgi trafficking machinery by regulating the transport to the plasma membrane rather than the endocytosis of surface MHC class I molecules, providing a novel mechanism of MHC class I down-regulation for immune escape.
Impairment of Mucosal Immunity by Total Parenteral Nutrition: Requirement for IgA in Murine Nasotracheal Anti-Influenza Immunity
Authors: Renegar Kathryn B. , Johnson Cheryl D. , Dewitt R. Chance , King Brock K. , Li Jian , Fukatsu Kazuhiko , Kudsk Kenneth A.
Published: April 2014

Secretory IgA (SIgA) is the primary mucosal Ig and has been shown to mediate nasotracheal (NT) mucosal immunity in normal immune BALB/c mice. This finding has been challenged by a report of NT immunity without IgA in knockout mice, suggesting that IgA may not be necessary for the protection of mucosal surfaces. Although other protective mechanisms may become active in the congenital absence of SIgA, these mechanisms are not the primary means of protection in normal mice. In this paper we show that feeding chemically defined total parenteral nutrition (TPN) to genetically normal, immune ICR mice by the i.v. route results in loss of nasal anti-influenza immunity and a significant drop in influenza-specific SIgA in the upper respiratory tract compared with chow-fed mice (p < 0.005), while the serum influenza-specific IgG titer is unaffected. Loss of upper respiratory tract mucosal immunity is not related to serum Ab, because 10 of 13 TPN-fed mice shed virus into their nasal secretions despite adequate serum anti-influenza IgG titers. The number of IgG Ab-secreting cells in the nasal passages and spleens of TPN-fed mice was unaffected, while both the number and the percentage of splenic IgA-secreting cells were decreased relative to those in chow-fed animals. The loss of immunity is due to the route of nutrition, not the composition of the diet, because TPN solution fed orally via gastrostomy instead of i.v. maintains NT anti-influenza mucosal immunity. We hypothesize that delivery of nutrition via the gut triggers the release of gastrointestinal neuropeptides necessary for maintenance of the mucosal immune system.
Different Programs of Activation-Induced Cell Death Are Triggered in Mature Activated CTL by Immunogenic and Partially Agonistic Peptide Ligands
Authors: Wei Cheng-Hong , Yagita Hideo , Masucci Maria G. , Levitsky Victor
Published: April 2014

Activation-induced cell death (AICD) of mature T cells plays an important role in the control of immune homeostasis and peripheral tolerance. TNFRs and Fas have been implicated in the induction of AICD. However, these molecules were shown to be dispensable, at least in some experimental systems, for downsizing of Ag-induced T cell expansions and development of tolerance in vivo. The conditions of T cell activation leading to T cell deletion in a death receptor-independent manner are not well characterized. Here we show that human CTLs die through a death receptor-independent apoptotic program upon triggering with a partially agonistic peptide ligand. This apoptotic process exhibits some features of T cell death due to lymphokine deprivation and is blocked by exogenous IL-2. Our data demonstrate that engagement of TCR by MHC-peptide complexes can trigger diverse apoptotic programs of AICD and that the choice between these programs is determined by the agonistic potency of MHC-peptide ligand.
Cutting Edge: Typhlocolitis in NF-κB-Deficient Mice
Authors: Erdman Susan E. , Fox James G. , Dangler Charles A. , Feldman Danielle , Horwitz Bruce H.
Published: April 2014

Activation of inflammatory gene expression by the transcription factor NF-κB is a central pathway in many inflammatory disorders, including colitis. Increased NF-κB activity has been linked with development of colitis in humans and animal models, thus it was unexpected when NF-κB-deficient mice developed spontaneous typhlocolitis. To further characterize this finding, we induced typhlocolitis in rederived NF-κB-deficient mice using intragastric infection with Helicobacter hepaticus. At 6 wk postinfection (PI), severe colitis with increased type 1 cytokine expression was seen in infected mice that lacked the p50 subunit of NF-κB and were also heterozygous for the p65 subunit of NF-κB(p50−/−p65+/−). Mice lacking the p50 subunit alone (p50−/−) were less severely affected, and wild-type mice and p65+/− mice were unaffected. T cell development in NF-κB-deficient mice was normal. These data indicate that p50 and p65 subunits of NF-κB have an unexpected role in inhibiting the development of colitis.
Chemokine Receptor Expressions and Responsiveness of Cord Blood T Cells
Authors: Sato Katsuaki , Kawasaki Hiroshi , Nagayama Hitomi , Enomoto Makoto , Morimoto Chikao , Tadokoro Kenji , Juji Takeo , Takahashi Tsuneo A.
Published: April 2014

Chemokines and their receptors play a critical role in the selective attraction of various subsets of leukocytes. We examined the chemokine receptor expressions and responsiveness of cord blood (CB) T cells. Flow-cytometric analysis revealed that peripheral blood (PB) T cells expressed CCR-1, CCR-2, CCR-5, CCR-6, CXC chemokine receptor-3 (CXCR-3), and CXCR-4, while CB T cells expressed only CXCR-4 on their surface. Chemotactic migratory response of CB T cells to macrophage-inflammatory protein (MIP)-1α, monocyte chemoattractant protein-1, RANTES, MIP-3α, monokine induced by IFN-γ, and IFN-γ-inducible protein-10 was significantly impaired compared with those of PB T cells. In contrast, the ability of CB T cells to migrate to MIP-3β, 6Ckine, and stromal cell-derived factor-1α was greater than that of PB T cells, and these events were correlated with the expression levels of CCR-7 and CXCR-4, respectively. Engagement of CD3 and CD28 specifically up-regulated CXCR-3 expression and chemotaxis to monokine induced by IFN-γ and IFN-γ-inducible protein-10, whereas this stimulation down-regulated CCR-7 expression and chemotaxis to MIP-3β and 6Ckine in PB T cells, but not in CB T cells. These results suggest that PB T cells and CB T cells exhibit distinct chemokine responsiveness via different chemokine receptor repertoire.
Reconstitution of a Functional Human Type II IL-4/IL-13 Receptor in Mouse B Cells: Demonstration of Species Specificity
Authors: Andrews Ryan P. , Rosa Lillian Rosa , Daines Michael O. , Khurana Hershey Gurjit K.
Published: April 2014

IL-13 is a Th2-derived pleiotropic cytokine that recently was shown to be a key mediator of allergic asthma. IL-13 mediates its effects via a complex receptor system, which includes the IL-4R α-chain, IL-4Rα, and at least two other cell surface proteins, IL-13Rα1 and IL-13Rα2, which specifically bind IL-13. IL-13 has been reported to have very limited effects on mouse B cells. It was unclear whether this was due to a lack of receptor expression, a disproportionate relative expression of the receptor components, or an additional subunit requirement in B cells. To determine the requirements for IL-13 signaling in murine B cells, we examined IL-13-dependent Stat6 activation and CD23 induction in the murine B cell line, A201.1. A201.1 cells responded to murine IL-4 via the type I IL-4R, but were unresponsive to IL-13, and did not express IL-13 receptor. B220+ splenocytes also failed to signal in response to IL-13 and did not express IL-13 receptor. We transfected A201.1 cells with human IL-4Rα, IL-13Rα1, or both. Transfectants expressing either human IL-4Rα or human IL-13Rα1 alone were unable to respond or signal to IL-13. Thus, human IL-13Rα1 could not combine with the endogenous murine IL-4Rα to generate a functional IL-13R. However, cells transfected with both human IL-4Rα and IL-13Rα1 responded to IL-13. Thus, the relative lack of IL-13 responsiveness in murine B cells is due to a lack of receptor expression. Furthermore, the heterodimeric interaction between IL-4Rα and IL-13Rα1 is species specific.
Expression of Mig (Monokine Induced by Interferon-γ) Is Important in T Lymphocyte Recruitment and Host Defense Following Viral Infection of the Central Nervous System
Authors: Liu Michael T. , Armstrong David , Hamilton Thomas A. , Lane Thomas E.
Published: April 2014

Induction of a Th1 immune response against viral infection of the CNS is important in contributing to viral clearance. The present studies demonstrate a role for the T cell chemoattractant chemokine Mig (monokine induced by IFN-γ) in contributing to a Th1 response against mouse hepatitis virus infection of the CNS. Analysis of the kinetics of Mig expression revealed mRNA transcripts present at days 7 and 12 postinfection (p.i.) but not early (day 2) or late (day 35) in the infection. To determine functional significance, mouse hepatitis virus-infected mice were treated with anti-Mig antisera, and the severity of disease was evaluated. Such treatment resulted in a marked increase in mortality that correlated with a >3 log increase in viral burden within the brains as compared with control mice treated with normal rabbit serum. Anti-Mig-treated mice displayed a significant decrease (p < 0.005) in CD4+ and CD8+ T cell recruitment into the CNS as compared with normal rabbit serum-treated mice. In addition, anti-Mig treatment resulted in a significant decrease (p < 0.05) in levels of IFN-γ and IFN-β that coincided with increased (p < 0.02) expression of the anti-inflammatory Th2 cytokine IL-10 within the CNS. Collectively, these data indicate that Mig is important in contributing to host defense by promoting a protective Th1 response against viral infection of the CNS.
A Novel Approach of Direct Ex Vivo Epitope Mapping Identifies Dominant and Subdominant CD4 and CD8 T Cell Epitopes from Listeria monocytogenes
Authors: Geginat Gernot , Schenk Simone , Skoberne Mojca , Goebel Werner , Hof Herbert
Published: April 2014

We used a novel approach for the direct ex vivo identification and characterization of T cell epitopes based on the screening of peptide spot libraries with freshly isolated splenocytes in a sensitive enzyme-linked immunospot (ELISPOT) assay. This technique was applied for the analysis of splenocytes from Listeria monocytogenes-infected BALB/c and C57BL/6 mice. The screening of peptide spot libraries covering the whole listeriolysin O and p60 of L. monocytogenes confirmed all known CD4 and CD8 T cell epitopes of these proteins and additionally revealed six new H-2d and six new H-2b-restricted T cell epitopes. New epitopes were categorized into CD4 and CD8 T cell epitopes by ex vivo ELISPOT analysis with separated T cell populations. The quantitative analysis of cells reactive with these CD4 and CD8 T cell epitopes revealed the existence of dominant and subdominant CD4 and CD8 T cell populations during L. monocytogenes infection. As a consequence of these data we suggest that ELISPOT-based screening of peptide spot libraries could be a general approach for the rapid identification and characterization of pathogen-specific T cell populations during various infectious diseases.
Protective Intestinal Anti-Rotavirus B Cell Immunity Is Dependent on α4β7 Integrin Expression But Does Not Require IgA Antibody Production
Authors: Kuklin Nelly A. , Rott Lusijah , Feng Ningguo , Conner Margaret E. , Wagner Norbert , Müller Werner , Greenberg Harry B.
Published: April 2014

Rotavirus (RV) is the main cause of severe gastroenteritis in young children; protection has been correlated with intestinal Ab responses. Using a mouse model of RV infection and β7-deficient (β7−/−) mice, which do not express α4β7 integrin, we demonstrated the importance of α4β7 integrin in B cell-mediated anti-RV immunity. β7−/− mice acutely infected with murine RV resolved infection and developed normal serum IgG Abs but had diminished intestinal IgA responses. α4β7−/− immune B cells did not resolve RV infection when adoptively transferred into RV-infected Rag-2-deficient mice. Fewer RV-specific B cells were found in the intestine of Rag-2-deficient mice transferred with β7−/− B cells compared with wild type. The absence of α4β7 expression and/or a lower frequency of IgA-producing cells among transferred β7−/− B cells could have accounted for the inability of these cells to resolve RV infection following passive transfer. To distinguish between these possibilities, we studied the importance of IgA production in RV infection using IgA-deficient (IgA−/−) mice. IgA−/− mice depleted of CD8+ T cells were able to clear primary RV infection. Similarly, adoptive transfer of immune IgA−/− B cells into chronically infected Rag-2-deficient mice resolved RV infection. We further demonstrated in both wild-type and IgA−/− mice that, following oral RV infection, protective B cells reside in the α4β7high population. Our findings suggest that α4β7 integrin expression is necessary for B cell-mediated immunity to RV independent of the presence of IgA.
The Hamster as a Model of Human Visceral Leishmaniasis: Progressive Disease and Impaired Generation of Nitric Oxide in the Face of a Prominent Th1-Like Cytokine Response
Authors: Melby Peter C. , Chandrasekar Bysani , Zhao Weigou , Coe John E.
Published: April 2014

Active human visceral leishmaniasis (VL) is characterized by a progressive increase in visceral parasite burden, cachexia, massive splenomegaly, and hypergammaglobulinemia. In contrast, mice infected with Leishmania donovani, the most commonly studied model of VL, do not develop overt, progressive disease. Furthermore, mice control Leishmania infection through the generation of NO, an effector mechanism that does not have a clear role in human macrophage antimicrobial function. Remarkably, infection of the Syrian hamster (Mesocricetus auratus) with L. donovani reproduced the clinicopathological features of human VL, and investigation into the mechanisms of disease in the hamster revealed striking differences from the murine model. Uncontrolled parasite replication in the hamster liver, spleen, and bone marrow occurred despite a strong Th1-like cytokine (IL-2, IFN-γ, and TNF/lymphotoxin) response in these organs, suggesting impairment of macrophage effector function. Indeed, throughout the course of infection, inducible NO synthase (iNOS, NOS2) mRNA or enzyme activity in liver or spleen tissue was not detected. In contrast, NOS2 mRNA and enzyme activity was readily detected in the spleens of infected mice. The impaired hamster NOS2 expression could not be explained by an absence of the NOS2 gene, overproduction of IL-4, defective TNF/lymphotoxin production (a potent second signal for NOS2 induction), or early dominant production of the deactivating cytokines IL-10 and TGF-β. Thus, although a Th1-like cytokine response was prominent, the major antileishmanial effector mechanism that is responsible for control of infection in mice was absent throughout the course of progressive VL in the hamster.