Summary Cherubism is an autosomal dominant syndrome characterized by inflammatory destructive bony lesions resulting in symmetrical deformities of the facial bones. Cherubism is caused by mutations in Sh3bp2, the gene that encodes the adaptor protein 3BP2. Most identified mutations in 3BP2 lie within the peptide sequence RSPPDG. A mouse model of cherubism develops hyperactive bone remodelling osteoclasts and systemic inflammation characterized by expansion of the myelomonocytic lineage. The mechanism by which cherubism mutations alter 3BP2 function has remained obscure. Here we show that Tankyrase, a member of the poly(ADP-ribose)polymerase (PARP) family, regulates 3BP2 stability through ADP-ribosylation and subsequent ubiquitylation by the E3-ubiquitin ligase RNF146 in osteoclasts. Cherubism mutations uncouple 3BP2 from Tankyrase-mediated protein destruction, which results in its stabilization and subsequent hyperactivation of the SRC, SYK and VAV signalling pathways.

The mounting of an effective immune response requires the coordinated function of both the innate and the adaptive arm of the immune system. Cells from both types of immunity respond to antigenic stimuli through a variety of surface and intracellular receptors and produce cytokines that tightly orchestrate the inflammatory response. The operation of feedback control mechanisms that regulate the duration and the amplitude of antigenic and cytokine receptor signaling is therefore required to prevent hyper-activation of the immune system that could lead to tissue destruction or autoimmunity. Suppressor of cytokine signaling (SOCS) proteins have been identified as a negative feedback loop to cytokine signaling. Recently, the generation of genetically engineered mouse models permitted the evaluation of their function in different processes of the immune responses. In this article, we review new insights into the modular structure of SOCS proteins and the function of SOCS1 and SOCS3 to negatively regulate activation and/or differentiation pathways in macrophages, dendritic cells, and T lymphocytes. Thus, SOCS family proteins are components of an emerging immunoregulatory mechanism that maintains the coordinated balance of both innate and adaptive immune responses.

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Objective. To investigate the expression of B7 costimulatory molecules in the lymphoepithelial lesions of salivary gland (SG) biopsy tissues and in SG epithe-lial cell lines derived from patients with Sjögren's syndrome (SS). Methods. B7.1 and B7.2 protein expression was studied by immunohistochemistry in minor SGs obtained from 11 patients with SS and 10 disease control patients with nonspecific sialadenitis and in cultured SG epithelial cell lines obtained from minor SGs from 15 SS patients and 15 control patients. B7.1 and B7.2 messenger RNA (mRNA) expression by SG epithelial cell lines was examined by reverse transcription-polymerase chain reaction (RT-PCR). Results. In biopsy tissues from SS patients, but not control patients, ductal and acinar epithelial cells showed increased expression of both B7.1 and B7.2. Intense spontaneous B7.1 protein expression (as well as HLA-ABC, but not B7.2 or HLA-DR) was also found in 73% of SG epithelial cell lines from SS patients versus 13% of those from control patients (P < 0.01). Interferon-treatment induced, or up-regulated, B7.1, B7.2, and HLA-DR expression in all SG epithelial cell lines tested. B7.1 and B7.2 expression by SG epithelial cell lines was also verified at the mRNA level by RT-PCR. Conclusion. Human SG epithelia are intrinsically capable of expressing B7 proteins upon activation. In SS patients, the expression of B7 molecules by SG epithe-lial tissues and by SG epithelial cell lines indicates the activated status of SG epithelial cells in this disorder and, possibly, their capacity for presenting antigens to T cells.

The complement system has been long regarded as an important effector of the innate immune response. Furthermore, complement contributes to various aspects of B and T cell immunity. Nevertheless, the role of complement in CD8+ T cell antiviral responses has yet to be fully delineated. We examined the CD8+ T cell response in influenza type A virus-infected mice treated with a peptide antagonist to C5aR to test the potential role of complement components in CD8+ T cell responses. We show that both the frequency and absolute numbers of flu-specific CD8+ T cells are greatly reduced in C5aR antagonist-treated mice compared with untreated mice. This reduction in flu-specific CD8+ T cells is accompanied by attenuated antiviral cytolytic activity in the lungs. These results demonstrate that the binding of the C5a component of complement to the C5a receptor plays an important role in CD8+ T cell responses.

SUMMARYCD40 has been identified in an expanding list of haematopoietic and non-haematopoietic cells and has received an increased interest based on its role in a variety of cell-mediated responses and its potential to participate in the pathogenesis of chronic inflammatory disorders. Sjögren's syndrome (SS) is an autoimmune exocrinopathy, which is characterized by chronic lymphocytic infiltration of exocrine glands and aberrant activation of epithelial tissues. We studied the expression of CD40 protein in cultured non-neoplastic salivary gland epithelial cell (SGEC) lines as well as in minor SG biopsies obtained from 17 SS patients and 12 controls. Immunocytochemical and flow cytometric analyses had revealed the occurrence of constitutively expressed CD40 molecules on the surface of long-term cultured SGEC lines, which could be further induced by interferon-gamma (IFN-g) and IL-1b cytokines, but not tumour necrosis factor-alpha (TNF-a), IL-4, IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF) or IFN-a. Triggering of SGEC through CD40 enhanced the surface expression of the adhesion molecule intercellular adhesion molecule-1 (ICAM-1)/CD54, but not MHC class I and class II (HLA-DR) molecules. Spontaneous CD40 expression was significantly higher in SGEC lines derived from SS patients, compared with controls (P < 0·001), which is suggestive of their intrinsically activated status. In SG biopsies, CD40 was constitutively expressed by lymphocytes, ductal epithelial cells and endothelial cells but not by other glandular cell types, such as acinar cells, myoepithelial cells and fibroblasts. In addition, CD40L staining was also detected in 30-50% of the infiltrating lymphocytes in the biopsies of SS patients. Our findings indicate the immunoregulatory potential of SGEC and lend further support to a model of intrinsic activation in salivary epithelia in SS, whereby these cells actively participate in the induction and maintenance of lymphocytic infiltrates of patients.

ICAM.1 (CD54) is a surface protein expressed on epithelial and other nonhematopoietic cells upon activation and is known to play an important role in the stimulation of T cells by the provision of cellular adhesion and costimulatory support. Sjogren's syndrome (SS) is an autoimmune exocrinopathy, which is characterized by chronic lymphocytic infiltration of exocrine glands and aberrant activation of epithelial tissues. To address the contribution of ICAM.1 in the pathogenesis of SS, the expression of this protein was studied by immunohistochemistry and flow cytometry in minor salivary gland (SG) biopsies as well as in cultured SG epithelial cell (SGEC) lines obtained from 18 SS patients and 16 controls. In biopsies from SS patients (but not controls), strong ICAM.1 was expressed by infiltrating mononuclear cells (52%) and by a significant proportion of periacinar myoepithelial cells (18%). In addition, a patchy pattern of moderate ICAM.1 expression was detected in 31% of ductal epithelia of SS patients. These ICAM.1‐expressing epithelial and myoepithelial cells were observed throughout glandular tissues and were not confined in areas proximal to lymphoid infiltrates. In support to an intrinsic activation profile of SGEC in SS, long‐term cultured non‐neoplastic SGEC lines derived from SS patients displayed significantly upregulated spontaneous expression of ICAM.1, compared to controls (P < 0.05). The high expression of ICAM.1 protein by the salivary epithelium of SS patients is likely suggestive of its important role in the pathogenesis of the disorder. Further, our results support a model of intrinsic activation of salivary epithelial and myoepithelial cells in SS, whereby these cells actively participate in the induction and maintenance of lymphocytic infiltrates of patients.

Epithelial cells appear to play an important role in the initiation and maintenance of autoimmune lesions in the salivary glands of patients with Sjogren's syndrome. Therefore, the detailed study of immunological function of salivary gland epithelial cells (SGEC) may provide useful information for the understanding of Sjögren's syndrome pathogenesis. In this report we aimed to formulate a protocol for the establishment of human non-neoplastic SGEC lines as a tool for the study of the physiology and pathophysiology of these cells. Pointing towards a practical approach, we sought to establish SGEC lines from quite a limited amount of biopsy tissue obtained during the diagnostic evaluation of patients. Herein, the favorable conditions for the long-term maintenance of human non-neoplastic SGEC lines are presented and involve the successive application of a serum-containing and a serum-free culture medium, supplemented with essential epithelial growth factors. This protocol has been found reliable and convenient, as attested by the reproducible establishment of non-neoplastic SGEC lines. The analysis of SGEC phenotypic features, as well as a coculture system for the study of interactions between epithelial cells and lymphocytes, are also described. Such techniques may provide valuable means for the functional and molecular investigation of human SGEC and particularly for the study of Sjögren's syndrome and other disorders of glandular epithelia.