Long Shen

Novel autoantibodies in Sjogren's syndrome.

Sjogrens syndrome (SS) is defined by autoantibodies to Ro and La. The current studies identified additional autoantibodies in SS to salivary gland protein 1 (SP-1), carbonic anhydrase 6 (CA6) and parotid secretory protein (PSP). These autoantibodies were present in two animal models for SS and occurred earlier in the course of the disease than antibodies to Ro or La. Patients with SS also produced antibodies to SP-1, CA6 and PSP. These antibodies were found in 45% of patients meeting the criteria for SS who lacked antibodies to Ro or La. Furthermore, in patients with idiopathic xerostomia and xerophthalmia for less than 2 years, 76% had antibodies to SP-1 and/or CA6 while only 31% had antibodies to Ro or La. Antibodies to SP-1, CA6 and PSP may be useful markers for identifying patients with SS at early stages of the disease or those that lack antibodies to either Ro or La.

Development of Autoimmunity in IL-14α-Transgenic Mice

Multiple genetic loci contribute to the development of systemic lupus erythematosus (SLE). In murine models for SLE, various genes on chromosome four have been implicated. IL-14 is a cytokine originally identified as a B cell growth factor. The il14 gene is located on chromosome 4. IL-14α is a cytokine encoded by the plus strand of the IL-14 gene using exons 3–10. The expression of IL-14α is increased in (NZB × NZW)F1 mice. In this study, we produced IL-14α-transgenic mice to study the role of IL-14α in the development of autoimmunity. At age 3–9 mo, IL-14α-transgenic mice demonstrate increased numbers of B1 cells in the peritoneum, increased serum IgM, IgG, and IgG 2a and show enhanced responses to T-dependent and T-independent Ags compared with littermate controls. At age 9–17 mo, IL-14α-transgenic mice develop autoantibodies, sialadenitis, as in Sjögren’s syndrome, and immune complex-mediated nephritis, as in World Health Organization class II SLE nephritis. Between the ages 14–18 mo, 95% of IL-14α-transgenic mice developed CD5+ B cell lymphomas, consistent with the lymphomas seen in elderly patients with Sjögren’s syndrome and SLE. These data support a role for IL-14α in the development of both autoimmunity and lymphomagenesis. These studies may provide a genetic link between these often related disorders.

IL-14 alpha, the nexus for primary Sjögren's disease in mice and humans.

To evaluate the role of interleukin 14 alpha (IL-14a) in Sjögrens syndrome (SS), we evaluated the expression of IL-14a in the peripheral blood lymphocytes (PBL) of patients with primary and secondary SS and normal controls by quantitative RT-PCR. In addition, transgenic IL-14a mice were analyzed from 6 weeks of age to death for both histological and immunological features of Sjögrens disease. Patients with both primary and secondary Sjögrens syndrome expressed IL-14a at statistically higher levels in their peripheral blood compared to normal controls matched for age, sex and ethnic group. Transgenic mice in which IL-14a expression was increased constitutively were previously demonstrated to develop hypergammaglobulinemia, autoantibodies, infiltration of the parotid glands with lymphocytes, mild immune-complex mediated renal disease and large B cell lymphoma. In this paper we expand these observations to demonstrate that these mice develop all the clinical and immunological features of primary Sjögrens disease in the same relative time frame as patients with primary Sjögrens disease: stage 1-early hypergammaglobulinemia and autoantibody production, stage 2-decreased salivary gland function with early lymphocytic infiltration of the submandibular glands only, but antibody deposition in the submandibular and parotid glands, stage 3-lymphocytic infiltration of the submandibular, parotid and lacrimal glands with B and T lymphocytes and plasma cells along with interstitial lung disease and mild renal disease, and stage 4-large B cell lymphoma. Thus IL-14a is important in the pathophysiology of Sjögrens disease. The IL-14a transgenic mouse is a novel animal model that can be utilized to understand the pathophysiology of Sjögrens disease.

A Role for Lymphotoxin in Primary Sjögren’s Disease

The etiology of salivary gland injury in primary Sjögren’s disease is not well understood. We have previously described a mouse model of Sjögren’s disease, IL-14α transgenic (IL14αTG) mice, which reproduces many of the features of the human disease. We now demonstrate a critical role for lymphotoxin α (LTA) in the pathogenesis of Sjögren’s disease in IL14αTG mice. IL14αTG mice express LTA mRNA in their salivary glands and spleen and produce soluble LTA protein in their salivary secretions. When IL14αTG mice were crossed with LTA−/− mice, the IL14αTG.LTA−/− mice retained normal salivary gland secretions and did not develop either lymphocytic infiltration of their salivary glands or secondary lymphomas. However, both IL14αTG and IL14αTG.LTA−/− mice produced similar amounts of IFN-α and had similar deposition of autoantibodies in their salivary glands. Both IL14α and IL14α/LTA−/− mice had similar B cell responses to T-dependent and T-independent Ags, L-selectin expression, and expression of RelA, RelB, and NF-κB2 in their spleens. These studies suggest that LTA plays a critical role in the local rather than systemic inflammatory process of Sjögren’s disease. Furthermore, local production of soluble LTA in the salivary glands of IL14αTG mice is necessary for the development of overt Sjögren’s disease. Autoantibody deposition alone is not sufficient to produce salivary gland dysfunction. We also demonstrate that LTA is increased in the salivary gland secretions and sera of patients with Sjögren’s disease, further strengthening the biological relevance of the IL14αTG model to understanding the pathogenesis of human disease.

Different Stages of Primary Sjögren’s Syndrome Involving Lymphotoxin and Type 1 IFN

Primary Sjögren’s syndrome (pSS) is a complex autoimmune disease starting in the salivary and lacrimal glands and continuing to involve the lungs and kidneys with the eventual development of lymphoma. Many studies have emphasized the role of type 1 IFN (IFN-α) and lymphotoxin α (LTα) in the pathogenesis of the disease. The present studies were designed to delineate the role of IFN-α in pSS using an animal model, the IL-14α (IL14αTG) transgenic mouse. IL14αTG mice lacking the type 1 IFNR (IL14αTG.IFNR−/−) had the same submandibular gland and lacrimal gland injury as did the IL14αTG mice, but they lacked the later parotid gland and lung injury. Development of lymphoma was delayed in IL14αTG.IFNR−/− mice. The switch from IgM to IgG autoantibodies as well as the increase in serum IgG2a seen is IL14αTG mice was inhibited in IL14αTG.IFNR−/− mice. Production of LTα was identified in both IL14αTG mice and IL14αTG.IFNR−/− mice at the time that salivary gland injury was occurring. These and previous studies suggest a model for pSS that separates the disease into several stages: 1) initial injury to the submandibular and lacrimal glands via an environmental insult and LTα; 2) amplification of local injury via the production of type 1 IFN; injury to the parotid glands, lungs, and kidneys is seen; 3) progression of systemic inflammation with the eventual development of large B cell lymphoma. Understanding these different stages will help to develop strategies for treatment of patients with pSS based on the status of their disease.

IP3R deficit underlies loss of salivary fluid secretion in Sjögren’s Syndrome

The autoimmune exocrinopathy, Sjögren’s syndrome (SS), is associated with secretory defects in patients, including individuals with mild lymphocytic infiltration and minimal glandular damage. The mechanism(s) underlying the secretory dysfunction is not known. We have used minor salivary gland biopsies from SS patients and healthy individuals to assess acinar cell function in morphologically intact glandular areas. We report that agonist-regulated intracellular Ca2+ release, critically required for Ca2+ entry and fluid secretion, is defective in acini from SS patients. Importantly, these acini displayed reduction in IP3R2 and IP3R3, but not AQP5 or STIM1. Similar decreases in IP3R and carbachol (CCh)-stimulated [Ca2+]i elevation were detected in acinar cells from lymphotoxin-alpha (LTα) transgenic (TG) mice, a model for (SS). Treatment of salivary glands from healthy individuals with LT α, a cytokine linked to disease progression in SS and IL14α mice, reduced Ca2+ signaling. Together, our findings reveal novel IP3R deficits in acinar cells that underlie secretory dysfunction in SS patients.

Investigation of novel autoantibodies in Sjogren’s syndrome utilizing Sera from the Sjogren’s international collaborative clinical alliance cohort

BackgroundSjogren’s syndrome (SS) is a chronic autoimmune disease mainly affecting salivary and lacrimal glands. Current diagnostic criteria for SS utilize anti-Ro and anti-La as serological markers. Animal models for SS have identified novel autoantibodies, anti-salivary gland protein 1 (SP1), anti-carbonic anhydrase 6 (CA6) and parotid secretory protein (PSP). These novel antibodies are seen in the animals at an earlier stage of SS than anti-Ro and anti-La. The current studies were designed to evaluate these novel autoantibodies in the sera of well-characterized patients with dry eyes and dry mouth and lip biopsies from the Sjogren’s International Collaborative Clinical Alliance (SICCA) to determine if they indeed identify SS with less severe disease than patients expressing anti-Ro and anti-La.MethodsSera were obtained from SICCA registry in patients for whom lymphocytic foci per 4 mm2 on the lip biopsies was either 0 (F = 0), <1 (F <1) or > 3 (F >3). ELISA assays were utilized to evaluate these sera for anti-Ro, anti-La, anti-SP1, anti-CA6, and anti-PSP.ResultsIn patients with dry eyes and dry mouth but F = 0, increased expression of anti- CA6 was noted compared to the F <1 group (p = .032) or the F > 3 group (p = .006). Neither anti-PSP nor anti-SP1 reached statistical significance because of the small numbers in the F0 group, although there was a trend for their expression to be higher in the F0 group. On the other hand, the expression of anti-Ro was significantly reduced in the F0 group compared to the F <1 (p = .0021) and F > 3 (p = .0003) groups. The reduced expression of anti-La in the F0 group compared to the F <1 and F > 3 groups did not quite reach statistical significance.ConclusionsAnti-Ro and anti-La identify patients with SS and more severe disease than anti-SP1, anti-CA6, and anti-PSP. More studies are needed to identify the timing in the course of SS when these different autoantibodies are expressed and/or whether they are expressed in patients with different clinical manifestations.

Side population of a murine mantle cell lymphoma model contains tumour-initiating cells responsible for lymphoma maintenance and dissemination

‘Cancer stem cells’ or ‘tumour initiating cells’ in B‐cell non‐Hodgkin lymphomas have not been demonstrated, although some studies focused on other cancer types suggest that such populations exist and represent tumour cells resistant to therapy and involved in relapse. These cells may also represent a putative neoplastic ‘cell of origin’ in lymphomas, but there is little substantive data to support this suggestion. Using cell lines derived from a recently established murine IL‐14α× c‐Myc double transgenic/mantle cell lymphoma‐blastoid variant model, heretofore referred to as DTG cell lines, we identified a subset of cells within the side population (SP) with features of ‘tumour‐initiating cells’. These features include higher expression of ABCG2 and BCL‐2, longer telomere length, greater self‐renewal ability and higher in vitro clonogenic and in vivo tumorigenic capacities compared with non‐SP. In addition, in vitro viability studies demonstrated that the non‐SP lymphoma subpopulation has a limited lifespan in comparison with the SP fraction. Syngenic transplant studies showed that non‐SP derived tumours, in comparison to the SP‐derived tumours, exhibit greater necrosis/apoptosis and less systemic dissemination capability. In conclusion, our data support the interpretation that the DTG SP fraction contains a cell population highly capable of tumour maintenance and systemic dissemination and lends support to the concept that ‘tumour‐initiating cells’ occur in lymphomas.

Central role for marginal zone B cells in an animal model of Sjogren's syndrome ☆

Patients with Sjogrens syndrome (SS) have been shown to have abnormal B cell function and increased numbers of marginal zone B cells (MZB and MZB precursors. The current studies utilized the Interleukin 14 alpha transgenic mouse model (IL14aTG) for SS to investigate the roles of marginal zone B cells (MZB) of the innate immune system in the pathophysiology of the disease. Eliminating MZB from IL14aTG mice by B cell specific deletion of RBP-J resulted in complete elimination of all disease manifestations of SS. Mice had normal salivary gland secretions, negative autoantibodies and normal histology of the salivary and lacrimal glands compared to IL14aTG mice at the same time points. In contrast, eliminating B1 cells by deleting btk did not ameliorate the disease. Therefore, MZB are critical for the development of SS.

Evaluation of salivary gland protein 1 antibodies in patients with primary and secondary Sjogren's syndrome

Sjogrens syndrome (SS) has been associated with the expression of anti-Ro and anti-La antibodies. Anti-salivary gland protein 1 (SP1) antibodies have recently been identified in patients with SS. The current work involved a cross sectional study to determine whether anti-SP1 antibodies were identified in particular subgroups of patients with SS. The results of this study revealed that anti-SP1 antibodies were present in the sera of 52% of SS patients while anti-Ro/anti-La was present in 63% of patients. 19% of patients had anti-SP1 without anti-Ro/anti-La. Patients with SS and lymphoma expressed anti-Ro, anti-La and anti-SP1 together. In SS associated with RA, 50% had antibodies anti-SP1 while 40% had anti-Ro/anti-La. In conclusion, anti-SP1 antibodies are commonly seen in both primary and secondary SS and rarely in normal controls. Future studies are needed to determine the roles and timing of expression of anti-SP1 antibodies in Sjogrens syndrome.