CD4+CD25+ regulatory T (TR) cells have been described in both humans and mice. In mice, TR are thymically derived, and lack of TR leads to organ-specific autoimmunity. Recently, the forkhead/winged helix transcription factor, FoxP3, has been shown to be important for the function of TR cells in mice. In this study, human TR cells were examined and, in results similar to those of studies done in mice, expression of FoxP3 was found exclusively in CD4+CD25+ T cells and correlated with the suppressive activity of these cells. In contrast to the mouse studies, activation of human CD4+CD25– T cells led to expression of FoxP3. Expression of FoxP3 in activated human CD4+CD25+ cells also correlated with suppression of proliferation by these cells in freshly isolated CD4+CD25– T cells from the same donor. This suppression was cell-contact dependent and cytokine independent. Thus, in humans, during activation of CD4+CD25– T cells in an immune response, two populations of cells may arise, effector CD4+CD25+ and regulatory CD4+CD25+ T cells, with expression of FoxP3 correlated with regulatory activity. These data also raise the possibility that a failure to generate peripheral TR cells properly may contribute to autoimmune disease and suggest a possible therapeutic role for FoxP3 in the treatment of such diseases.
Mindi R.Walker, Deborah J. Kasprowicz, Vivian H. Gersuk, Angéle Bènard, Megan Van Landeghen, Jane H. Buckner, Steven F. Ziegler
X-linked anhidrotic ectodermal dysplasia with immunodeficiency (XL-EDA-ID) is caused by hypomorphic mutations in the gene encoding NEMO/IKKγ, the regulatory subunit of the IκB kinase (IKK) complex. IKK normally phosphorylates the IκB-inhibitors of NF-κB at specific serine residues, thereby promoting their ubiquitination and degradation by the proteasome. This allows NF-κB complexes to translocate into the nucleus where they activate their target genes. Here, we describe an autosomal-dominant (AD) form of EDA-ID associated with a heterozygous missense mutation at serine 32 of IκBα. This mutation is gain-of-function, as it enhances the inhibitory capacity of IκBα by preventing its phosphorylation and degradation, and results in impaired NF-κB activation. The developmental, immunologic, and infectious phenotypes associated with hypomorphic NEMO and hypermorphic IKBA mutations largely overlap and include EDA, impaired cellular responses to ligands of TIR (TLR-ligands, IL-1β, and IL-18), and TNFR (TNF-α, LTα1/β2, and CD154) superfamily members and severe bacterial diseases. However, AD-EDA-ID but not XL-EDA-ID is associated with a severe and unique T cell immunodeficiency. Despite a marked blood lymphocytosis, there are no detectable memory T cells in vivo, and naive T cells do not respond to CD3-TCR activation in vitro. Our report highlights both the diversity of genotypes associated with EDA-ID and the diversity of immunologic phenotypes associated with mutations in different components of the NF-κB signaling pathway.
Gilles Courtois, Asma Smahi, Janine Reichenbach, Rainer Döffinger, Caterina Cancrini, Marion Bonnet, Anne Puel, Christine Chable-Bessia, Shoji Yamaoka, Jacqueline Feinberg, Sophie Dupuis-Girod, Christine Bodemer, Susanna Livadiotti, Francesco Novelli, Paolo Rossi, Alain Fischer, Alain Israël, Arnold Munnich, Françoise Le Deist, Jean-Laurent Casanova
Containment of hepatitis C virus (HCV) and other chronic human viral infections is associated with persistence of virus-specific CD4 T cells, but ex vivo characterization of circulating CD4 T cells has not been achieved. To further define the phenotype and function of these cells, we developed a novel approach for the generation of tetrameric forms of MHC class II/peptide complexes that is based on the cellular peptide-exchange mechanism. HLA-DR molecules were expressed as precursors with a covalently linked CLIP peptide, which could be efficiently exchanged with viral peptides following linker cleavage. In subjects who spontaneously resolved HCV viremia, but not in those with chronic progressive infection, HCV tetramer–labeled cells could be isolated by magnetic bead capture despite very low frequencies (1:1,200 to 1:111,000) among circulating CD4 T cells. These T cells expressed a set of surface receptors (CCR7+CD45RA–CD27+) indicative of a surveillance function for secondary lymphoid structures and had undergone significant in vivo selection since they utilized a restricted Vβ repertoire. These studies demonstrate a relationship between clinical outcome and the presence of circulating CD4 T cells directed against this virus. Moreover, they show that rare populations of memory CD4 T cells can be studied ex vivo in human diseases.
Cheryl L. Day, Nilufer P. Seth, Michaela Lucas, Heiner Appel, Laurent Gauthier, Georg M. Lauer, Gregory K. Robbins, Zbigniew M. Szczepiorkowski, Deborah R. Casson, Raymond T. Chung, Shannon Bell, Gillian Harcourt, Bruce D. Walker, Paul Klenerman, Kai W. Wucherpfennig
CD69 is induced after activation of leukocytes at inflammatory sites, but its physiological role during inflammation remains unknown. We explored the role of CD69 in autoimmune reactivity by analyzing a model of collagen-induced arthritis (CIA) in WT and CD69-deficient mice. CD69–/– mice showed higher incidence and severity of CIA, with exacerbated T and B cell immune responses to type II collagen. Levels of TGF-β1 and TGF-β2, which act as protective agents in CIA, were reduced in CD69–/– mice inflammatory foci, correlating with the increase in the proinflammatory cytokines IL-1β and RANTES. Local injection of blocking anti–TGF-β antibodies increased CIA severity and proinflammatory cytokine mRNA levels in CD69+/+ but not in CD69–/– mice. Moreover, in vitro engagement of CD69 induced total and active TGF-β1 production in Concanavalin A–activated splenocyte subsets, mouse and human synovial leukocytes, and Jurkat stable transfectants of human CD69 but not in the parental CD69 negative cell line. Our results show that CD69 is a negative modulator of autoimmune reactivity and inflammation through the synthesis of TGF-β, a cytokine that in turn downregulates the production of various proinflammatory mediators.
David Sancho, Manuel Gómez, Fernando Viedma, Enric Esplugues, Mónica Gordón-Alonso, María Angeles García-López, Hortensia de la Fuente, Carlos Martínez-A, Pilar Lauzurica, Francisco Sánchez-Madrid
CD1d is expressed on the surface of professional and nonprofessional APCs, including intestinal epithelial cells (IECs), for a role in the presentation of glycolipid-based antigens to subsets of T cells. The mechanisms that regulate CD1d expression in any cell type are unknown. To investigate the possibility that expression of CD1d is influenced by exogenous factors present within the intestinal lumen, CD1d expression was analyzed in several IEC lines after culturing in the presence of lumenal contents (LC) of the normal human intestine. Exposure of the colon-derived cell lines T84, HT-29, and Caco-2 to soluble LC resulted in a marked induction of CD1d expression as determined by RT-PCR, confocal microscopy, cell surface ELISA, and Western blot analysis. Similarly, exposure of human IECs to LC isolated from mice bred in both specific pathogen–free and germfree conditions also resulted in the induction of CD1d expression, with the maximum CD1d-inducing activity observed in the small intestine. Biochemical and biophysical characterization of the human CD1d-inducing activity identified heat shock protein 110 (Hsp110) as a major functional component of the LC that contributes to CD1d surface regulation, and immunolocalization studies revealed Hsp110 expression in subsets of human IECs in vivo. These data support the presence of a novel autocrine pathway of CD1d regulation by Hsp110.
Sean P. Colgan, Richard S. Pitman, Takashi Nagaishi, Atsushi Mizoguchi, Emiko Mizoguchi, Lloyd F. Mayer, Ling Shao, R. Balfour Sartor, John R. Subjeck, Richard S. Blumberg
IL-12 p40–related cytokines such as IL-12 p35/p40 heterodimer and IL-23 (p19/p40) are potent regulators of adaptive immune responses. Little is known, however, about the transcriptional regulation of the p40 gene in vivo. In an attempt toward this goal, we have generated transgenic mice expressing firefly luciferase under the control of the IL-12 p40 promoter. High constitutive transgene expression was found in the small intestine only, whereas little reporter gene activity was observed in other tissues. Within the small bowel, constitutive promoter activity was restricted to the terminal ileum and associated with high expression of p40 mRNA as well as p40 and IL-23 p19/p40 proteins. The cells constitutively producing IL-12 p40 were identified as CD8α and CD11b double-negative CD11c+ lamina propria dendritic cells (LPDCs) that represent a major cell population in the lamina propria of the small intestine, but not in the colon. FISH directly demonstrated the uptake of bacteria by a subset of LPDCs in the terminal ileum that was associated with p40 expression. Furthermore, little or no p40 protein expression in LPDCs was found in the terminal ileum of germfree mice, indicating a key role of the intestinal flora for constitutive p40 expression. In addition, analysis of transgenic mice with a mutated NF-κB target site in the p40 promoter showed a critical role of NF-κB for constitutive transgene expression. Our data reveal important functional differences between the mucosal immune systems of the small and large bowel in healthy mice and suggest that the high bacterial load in the terminal ileum activates p40 gene transcription in LPDCs through NF-κB. These data suggest a predisposition of the terminal ileum to develop chronic inflammatory responses through IL-23 and thus may provide a molecular explanation for the preferential clinical manifestation of Crohn disease in this part of the gut.
Christoph Becker, Stefan Wirtz, Manfred Blessing, Jaana Pirhonen, Dennis Strand, Oliver Bechthold, Julia Frick, Peter R. Galle, Ingo Autenrieth, Markus F. Neurath
Regulated recruitment and clearance of neutrophils (PMN) is the hallmark of competent host defense and resolution of inflammation. We now report that IFN-γ controls PMN infiltration and modulates IL-6 signaling through its soluble receptor (sIL-6R) to promote their apoptosis and clearance. Induction of peritoneal inflammation in IFN-γ–deficient (IFN-γ–/–) mice emphasized that the initial rate of PMN recruitment was impaired. This defect in PMN recruitment was also associated with the suppressed intraperitoneal expression of IL-1β and IL-6. Reconstitution of IFN-γ signaling restored the rate of PMN infiltration and IL-6 levels and was accompanied by normalization of PMN-activating CXC chemokine expression. To test whether local IL-6 signaling modulated PMN recruitment, inflammation was induced in IFN-γ–/– and IL-6–/– mice and cytokine signaling adapted by intraperitoneal sIL-6R–IL-6 fusion protein (HYPER-IL-6) or IFN-γ. Although HYPER-IL-6 attenuated PMN influx in IFN-γ–/– mice, IFN-γ had no effect on PMN infiltration in IL-6–/– mice. Examination of the leukocyte infiltrate from IFN-γ–/–, IL-6–/–, and wild-type mice showed that apoptosis was aberrant in the absence of IFN-γ and IL-6 as a result of impaired sIL-6R signaling. These data emphasize a pivotal role for IFN-γ in regulating innate immunity through control of both the recruitment and clearance phases of PMN trafficking.
Rachel M. McLoughlin, Janusz Witowski, Rachel L. Robson, Thomas S. Wilkinson, Suzanne M. Hurst, Anwen S. Williams, John D. Williams, Stefan Rose-John, Simon A. Jones, Nicholas Topley
IL-13 is an important mediator of inflammation and remodeling. We hypothesized that adenosine accumulation, alterations in adenosine receptors, and adenosine–IL-13 autoinduction are critical events in IL-13–induced pathologies. To test this, we characterized the effects of IL-13 overexpression on the levels of adenosine, adenosine deaminase (ADA) activity, and adenosine receptors in the murine lung. We also determined whether adenosine induced IL-13 in lungs from ADA-null mice. IL-13 induced an inflammatory and remodeling response that caused respiratory failure and death. During this response, IL-13 caused a progressive increase in adenosine accumulation, inhibited ADA activity and mRNA accumulation, and augmented the expression of the A1, A2B, and A3 but not the A2A adenosine receptors. ADA enzyme therapy diminished the IL-13–induced increase in adenosine, inhibited IL-13–induced inflammation, chemokine elaboration, fibrosis, and alveolar destruction, and prolonged the survival of IL-13–transgenic animals. In addition, IL-13 was strongly induced by adenosine in ADA-null mice. These findings demonstrate that adenosine and adenosine signaling contribute to and influence the severity of IL-13–induced tissue responses. They also demonstrate that IL-13 and adenosine stimulate one another in an amplification pathway that may contribute to the nature, severity, progression, and/or chronicity of IL-13 and/or Th2-mediated disorders.
Michael R. Blackburn, Chun G. Lee, Hays W.J. Young, Zhou Zhu, Janci L. Chunn, Min Jong Kang, Suman K. Banerjee, Jack A. Elias
Galectin-3 is a member of a large family of animal lectins. This protein is expressed abundantly by macrophages, but its function in this cell type is not well understood. We have studied the effect of galectin-3 gene targeting on phagocytosis, a major function of macrophages. Compared with wild-type macrophages, galectin-3–deficient (gal3–/–) cells exhibited reduced phagocytosis of IgG-opsonized erythrocytes and apoptotic thymocytes in vitro. In addition, gal3–/– mice showed attenuated phagocytic clearance of apoptotic thymocytes by peritoneal macrophages in vivo. These mice also exhibited reduced IgG-mediated phagocytosis of erythrocytes by Kupffer cells in a murine model of autoimmune hemolytic anemia. Additional experiments indicate that extracellular galectin-3 does not contribute appreciably to the phagocytosis-promoting function of this protein. Confocal microscopic analysis of macrophages containing phagocytosed erythrocytes revealed localization of galectin-3 in phagocytic cups and phagosomes. Furthermore, gal3–/– macrophages exhibited a lower degree of actin rearrangement upon Fcγ receptor crosslinkage. These results indicate that galectin-3 contributes to macrophage phagocytosis through an intracellular mechanism. Thus, galectin-3 may play an important role in both innate and adaptive immunity by contributing to phagocytic clearance of microorganisms and apoptotic cells.
Hideki Sano, Daniel K. Hsu, John R. Apgar, Lan Yu, Bhavya B. Sharma, Ichiro Kuwabara, Shozo Izui, Fu-Tong Liu
Alzheimer disease (AD) is characterized by the progressive deposition of the 42-residue amyloid β protein (Aβ) in brain regions serving memory and cognition. In animal models of AD, immunization with Aβ results in the clearance of Aβ deposits from the brain. However, a trial of vaccination with synthetic human Aβ1–42 in AD resulted in the development of meningoencephalitis in some patients. We measured cellular immune responses to Aβ in middle-aged and elderly healthy subjects and in patients with AD. A significantly higher proportion of healthy elderly subjects and patients with AD had strong Aβ-reactive T cell responses than occurred in middle-aged adults. The immunodominant Aβ epitopes in humans resided in amino acids 16–33. Epitope mapping enabled the identification of MHC/T cell receptor (TCR) contact residues. The occurrence of intrinsic T cell reactivity to the self-antigen Aβ in humans has implications for the design of Aβ vaccines, may itself be linked to AD susceptibility and course, and appears to be associated with the aging process.
Alon Monsonego, Victor Zota, Arnon Karni, Jeffery I. Krieger, Amit Bar-Or, Gal Bitan, Andrew E. Budson, Reisa Sperling, Dennis J. Selkoe, Howard L. Weiner