X-linked lymphoproliferative disease (XLP) is an often-fatal immunodeficiency characterized by hypogammaglobulinemia, fulminant infectious mononucleosis, and/or lymphoma. The genetic lesion in XLP, SH2D1A, encodes the adaptor protein SAP (signaling lymphocytic activation molecule–associated [SLAM-associated] protein); however, the mechanism(s) by which mutations in SH2D1A causes hypogammaglobulinemia is unknown. Our analysis of 14 XLP patients revealed normal B cell development but a marked reduction in the number of memory B cells. The few memory cells detected were IgM+, revealing deficient isotype switching in vivo. However, XLP B cells underwent proliferation and differentiation in vitro as efficiently as control B cells, which indicates that the block in differentiation in vivo is B cell extrinsic. This possibility is supported by the finding that XLP CD4+ T cells did not efficiently differentiate into IL-10+ effector cells or provide optimal B cell help in vitro. Importantly, the B cell help provided by SAP-deficient CD4+ T cells was improved by provision of exogenous IL-10 or ectopic expression of SAP, which resulted in increased IL-10 production by T cells. XLP CD4+ T cells also failed to efficiently upregulate expression of inducible costimulator (ICOS), a potent inducer of IL-10 production by CD4+ T cells. Thus, insufficient IL-10 production may contribute to hypogammaglobulinemia in XLP. This finding suggests new strategies for treating this immunodeficiency.
Cindy S. Ma, Nathan J. Hare, Kim E. Nichols, Loic Dupré, Grazia Andolfi, Maria-Grazia Roncarolo, Stephen Adelstein, Philip D. Hodgkin, Stuart G. Tangye
Osteopontin (OPN) is an extracellular matrix protein of pleiotropic properties and has been recently recognized as a potential inflammatory cytokine. In this study, we demonstrate, for the first time to our knowledge, that overexpression of OPN in synovial T cells is associated with local inflammatory milieu and that OPN acts as an important mediator in amplification and perpetuation of rheumatoid synovitis. The study revealed that mRNA expression of OPN was highly elevated in CD4+ synovial T cells derived from patients with RA, which correlated with increased OPN concentrations in synovial fluid (SF). The pattern of OPN overexpression was confined to rheumatoid synovium and correlated with coexpression of selected OPN receptors in synovial T cells, including integrins αv and β1 and CD44. RA-derived SF stimulated the expression of OPN in T cells, which was attributable to IL-10 present in SF and abrogated by anti–IL-10 antibody. Among the more than 300 autoimmune and inflammatory response genes examined, OPN selectively induced the expression of proinflammatory cytokines and chemokines known to promote migration and recruitment of inflammatory cells. Furthermore, it was evident that OPN activated transcription factor NF-κB in mononuclear cells. The study has important implications for understanding the role of OPN in rheumatoid synovitis and other inflammatory conditions.
Guangwu Xu, Hong Nie, Ningli Li, Wenxin Zheng, Dongqing Zhang, Guozhang Feng, Liqing Ni, Rong Xu, Jian Hong, Jingwu Z. Zhang
In papillary thyroid carcinomas (PTCs), rearrangements of the RET receptor (RET/PTC) and activating mutations in the BRAF or RAS oncogenes are mutually exclusive. Here we show that the 3 proteins function along a linear oncogenic signaling cascade in which RET/PTC induces RAS-dependent BRAF activation and RAS- and BRAF-dependent ERK activation. Adoptive activation of the RET/PTC-RAS-BRAF axis induced cell proliferation and Matrigel invasion of thyroid follicular cells. Gene expression profiling revealed that the 3 oncogenes activate a common transcriptional program in thyroid cells that includes upregulation of the CXCL1 and CXCL10 chemokines, which in turn stimulate proliferation and invasion. Thus, motile and mitogenic properties are intrinsic to transformed thyroid cells and are governed by an epistatic oncogenic signaling cascade.
Rosa Marina Melillo, Maria Domenica Castellone, Valentina Guarino, Valentina De Falco, Anna Maria Cirafici, Giuliana Salvatore, Fiorina Caiazzo, Fulvio Basolo, Riccardo Giannini, Mogens Kruhoffer, Torben Orntoft, Alfredo Fusco, Massimo Santoro
T cell activation levels in HIV infection are predictive of AIDS progression. We searched for the immunological correlates of protection against disease progression by studying the early stages of nonpathogenic SIV infection in African green monkeys (SIVagm). The African green monkeys (AGMs) displayed high peak viremias and a transient decline in levels of blood CD4+ and CD8+ T cells between days 5 and 17 after infection. A concomitant increase in levels of CD4+DR+, CD8+DR+, and CD8+CD28– cells was detected. After the third week, T cell activation returned to baseline levels, which suggested a protective downregulation of T cell activation. A very early (24 hours after infection) and strong induction of TGF-β1 and FoxP3 expression was detected and correlated with increases in levels of CD4+CD25+ and CD8+CD25+ T cells. This was followed by a significant increase in levels of IL-10, whereas IFN-γ gene upregulation was more transient, and levels of TNF-α and MIP-1α/β transcripts did not increase in either blood or tissues. The profiles were significantly different during primary SIV infection in macaques (SIVmac); that is, there was a delayed increase in IL-10 levels accompanied by moderate and persistent increases in TGF-β levels. Together, our data show that SIVagm infection is associated with an immediate antiinflammatory environment and suggest that TGF-β may participate in the generation of Tregs, which may prevent an aberrant chronic T cell hyperactivation.
Christopher Kornfeld, Mickaël J.-Y. Ploquin, Ivona Pandrea, Abdourahmane Faye, Richard Onanga, Cristian Apetrei, Virginie Poaty-Mavoungou, Pierre Rouquet, Jérôme Estaquier, Lorenzo Mortara, Jean-François Desoutter, Cécile Butor, Roger Le Grand, Pierre Roques, François Simon, Françoise Barré-Sinoussi, Ousmane M. Diop, Michaela C. Müller-Trutwin
Angiotensin II, acting through type 1 angiotensin (AT1) receptors, has potent effects that alter renal excretory mechanisms. Control of sodium excretion by the kidney has been suggested to be the critical mechanism for blood pressure regulation by the renin-angiotensin system (RAS). However, since AT1 receptors are ubiquitously expressed, precisely dissecting their physiological actions in individual tissue compartments including the kidney with conventional pharmacological or gene targeting experiments has been difficult. Here, we used a cross-transplantation strategy and AT1A receptor–deficient mice to demonstrate distinct and virtually equivalent contributions of AT1 receptor actions in the kidney and in extrarenal tissues to determining the level of blood pressure. We demonstrate that regulation of blood pressure by extrarenal AT1A receptors cannot be explained by altered aldosterone generation, which suggests that AT1 receptor actions in systemic tissues such as the vascular and/or the central nervous systems make nonredundant contributions to blood pressure regulation. We also show that interruption of the AT1 receptor–mediated short-loop feedback in the kidney is not sufficient to explain the marked stimulation of renin production induced by global AT1 receptor deficiency or by receptor blockade. Instead, the renin response seems to be primarily determined by renal baroreceptor mechanisms triggered by reduced blood pressure. Thus, the regulation of blood pressure by the RAS is mediated by AT1 receptors both within and outside the kidney.
Steven D. Crowley, Susan B. Gurley, Michael I. Oliverio, A. Kathy Pazmino, Robert Griffiths, Patrick J. Flannery, Robert F. Spurney, Hyung-Suk Kim, Oliver Smithies, Thu H. Le, Thomas M. Coffman
The inhibitor of NF-κB (I-κB) kinase (IKK) complex consists of 3 subunits, IKK1, IKK2, and NF-κB essential modulator (NEMO), and is involved in the activation of NF-κB by various stimuli. IKK2 or NEMO constitutive knockout mice die during embryogenesis as a result of massive hepatic apoptosis. Therefore, we examined the role of IKK2 in TNF-induced apoptosis and ischemia/reperfusion (I/R) injury in the liver by using conditional knockout mice. Hepatocyte-specific ablation of IKK2 did not lead to impaired activation of NF-κB or increased apoptosis after TNF-α stimulation whereas conditional NEMO knockout resulted in complete block of NF-κB activation and massive hepatocyte apoptosis. In a model of partial hepatic I/R injury, mice lacking IKK2 in hepatocytes displayed significantly reduced liver necrosis and inflammation than wild-type mice. AS602868, a novel chemical inhibitor of IKK2, protected mice from liver injury due to I/R without sensitizing them toward TNF-induced apoptosis and could therefore emerge as a new pharmacological therapy for liver resection, hemorrhagic shock, or transplantation surgery.
Tom Luedde, Ulrike Assmus, Torsten Wüstefeld, Andreas Meyer zu Vilsendorf, Tania Roskams, Mark Schmidt-Supprian, Klaus Rajewsky, David A. Brenner, Michael P. Manns, Manolis Pasparakis, Christian Trautwein
Increasing evidence demonstrates that IL-6 has a protective role during liver injury. IL-6 activates intracellular pathways via the gp130 receptor. In order to identify IL-6–gp130 pathways involved in mediating liver protection, we analyzed hepatocyte-specific gp130 knockout mice in a concanavalin A–induced (Con A–induced) model of immune-mediated hepatitis. We demonstrated that IL-6–gp130–dependent pathways in hepatocytes alone are sufficient for triggering protection in Con A–induced hepatitis. gp130-STAT3 signaling in hepatocytes mediates the IL-6–triggered protective effect. This was demonstrated by analysis of IL-6–induced protection in mice selectively deficient for gp130-dependent STAT1/3 or gp130-SHP2-RAS signaling in hepatocytes. To identify IL-6–gp130–STAT1/3 dependently expressed liver-protective factors, we performed gene array analysis of hepatic gene expression in hepatocyte-specific gp130–/– mice as well as in gp130-STAT1/3– and gp130-SHP2-RAS-MAPK–deficient mice. The mouse IL-8 ortholog KC (also known as Gro-α) and serum amyloid A2 (SAA2) was identified as differentially IL-6–gp130–STAT3–regulated genes. Hepatic expression of KC and SAA2 mediate the liver-protective potential of IL-6, since treatment with recombinant KC or serum SAA2 effectively reduced liver injury during Con A–induced hepatitis. In summary, this study defines IL-6–gp130–STAT3–dependent gene expression in hepatocytes that mediates IL-6–triggered protection in immune-mediated Con A–induced hepatitis. Additionally, we identified the IL-6–gp130–STAT3–dependent proteins KC and SAA2 as new candidates for therapeutic targets in liver diseases.
Christian Klein, Torsten Wüstefeld, Ulrike Assmus, Tania Roskams, Stefan Rose-John, Michael Müller, Michael P. Manns, Mattias Ernst, Christian Trautwein
Epidermolysis bullosa acquisita (EBA) is a subepidermal blistering disorder associated with tissue-bound and circulating autoantibodies specific to type VII collagen, a major constituent of the dermal-epidermal junction. Previous attempts to transfer the disease by injection of patient autoantibodies into mice have been unsuccessful. To study the pathogenic relevance of antibodies specific to type VII collagen in vivo, we generated and characterized rabbit antibodies specific to a murine form of this antigen and passively transferred them into adult nude, BALB/c, and C57BL/6 mice. Immune rabbit IgG bound to the lamina densa of murine skin and immunoblotted type VII collagen. Mice injected with purified IgG specific to type VII collagen, in contrast to control mice, developed subepidermal skin blisters, reproducing the human disease at the clinical, histological, electron microscopical, and immunopathological levels. Titers of rabbit IgG in the serum of mice correlated with the extent of the disease. F(ab′)2 fragments of rabbit IgG specific to type VII collagen were not pathogenic. When injected into C5-deficient mice, antibodies specific to type VII collagen failed to induce the disease, whereas C5-sufficient mice were susceptible to blister induction. This animal model for EBA should facilitate further dissection of the pathogenesis of this disease and development of new therapeutic strategies.
Cassian Sitaru, Sidonia Mihai, Christoph Otto, Mircea T. Chiriac, Ingrid Hausser, Barbara Dotterweich, Hitoshi Saito, Christian Rose, Akira Ishiko, Detlef Zillikens
Extracellular proteolysis by the plasminogen/plasmin (Plg/plasmin) system and MMPs is required for tissue injury in autoimmune and inflammatory diseases. We demonstrate that a Plg cascade synergizes with MMP-9/gelatinase B in vivo during dermal-epidermal separation in an experimental model of bullous pemphigoid (BP), an autoimmune disease. BP was induced in mice by antibodies to the hemidesmosomal antigen BP180. Mice deficient in MMP-9 were resistant to experimental BP, while mice deficient in Plg and both tissue Plg activator (tPA) and urokinase Plg activator (uPA) showed delayed and less intense blister formation induced by antibodies to BP180. Plg-deficient mice reconstituted locally with Plg or the active form of MMP-9 (actMMP-9), but not the proenzyme form of MMP-9 (proMMP-9), developed BP. In contrast, proMMP-9 or actMMP-9, but not Plg, reconstituted susceptibility of MMP-9–deficient mice to the skin disease. In addition, MMP-3–deficient mice injected with pathogenic IgG developed the same degree of BP and expressed levels of actMMP-9 in the skin similar to those of WT controls. Thus, the Plg/plasmin system is epistatic to MMP-9 activation and subsequent dermal-epidermal separation in BP.
Zhi Liu, Ning Li, Luis A. Diaz, Michael Shipley, Robert M. Senior, Zena Werb
Pemphigus is a life-threatening blistering disorder of the skin and mucous membranes caused by pathogenic autoantibodies to desmosomal adhesion proteins desmoglein 3 (Dsg3) and Dsg1. Mechanisms of antibody pathogenicity are difficult to characterize using polyclonal patient sera. Using antibody phage display, we have isolated repertoires of human anti-Dsg mAbs as single-chain variable-region fragments (scFvs) from a patient with active mucocutaneous pemphigus vulgaris. ScFv mAbs demonstrated binding to Dsg3 or Dsg1 alone, or both Dsg3 and Dsg1. Inhibition ELISA showed that the epitopes defined by these scFvs are blocked by autoantibodies from multiple pemphigus patients. Injection of scFvs into neonatal mice identified 2 pathogenic scFvs that caused blisters histologically similar to those observed in pemphigus patients. Similarly, these 2 scFvs, but not others, induced cell sheet dissociation of cultured human keratinocytes, indicating that both pathogenic and nonpathogenic antibodies were isolated. Genetic analysis of these mAbs showed restricted patterns of heavy and light chain gene usage, which were distinct for scFvs with different desmoglein-binding specificities. Detailed characterization of these pemphigus mAbs should lead to a better understanding of the immunopathogenesis of disease and to more specifically targeted therapeutic approaches.
Aimee S. Payne, Ken Ishii, Stephen Kacir, Chenyan Lin, Hong Li, Yasushi Hanakawa, Kazuyuki Tsunoda, Masayuki Amagai, John R. Stanley, Don L. Siegel
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