Pathogenesis
Treatment

Abstract 1123: Over-Expression of Interferon-Inducible Genes is Highly Correlated with Sicca Manifestations and Autoantibody Levels in Sjogrens Syndrome
Eshrat S. Emamian, Joanlise Leon, Shaoqi Rao, Carolyn M Meyer, AmberN Leiran, Emily C Gillespie, Timothy W Behrens, Barbara Segal, Nelson L Rhodus, Kathy L Moser.

Purpose: The authors used high density oligonucleotide microarray technology to compare global gene expression profiles in peripheral blood samples of Sjogrens Syndrome (SS) patients and controls.

Methods: All 45 study patients met the 2002 revised European criteria for classification of primary SS. Initial studies using peripheral blood mononuclear cells indicated that differential gene expression patterns were detectable in SS patients (n=22) compared with healthy controls (n=23). Over 400 differentially expressed genes were identified. A prominent pattern of overexpressed interferon-inducible genes was identified. The investigators also confirmed this gene expression pattern independently in a second dataset consisting of 16 patients and 22 controls using whole blood samples. Comparison of differentially expressed genes in both datasets revealed a list of 41 overlapping genes, most of which are known to be inducible by interferons.

The authors next sought to examine clinical correlations with gene expression. Utilizing an expanded dataset of 34 patients and 22 matched controls, levels of over 22,000 genes were measured using Affymetrix U133A microarray. Within the SS patient group, clinical variables were correlated o genes present in the over expressed IFN-inducible cluster. Anti-Ro/SSA titers, anti-La/SSB titers, and ESRs were positively correlated to the expression values of the clustered interferon stimulated genes (p<0.05). Salivary flow and tear production values were negatively correlated to these genes (p<0.05), indicating that patients with lower amounts of saliva and tears had higher expression of IFN stimulated genes.

Conclusion: Data from this study demonstrates a convincing role for interferon-related pathways in SS and show that expression of these genes is correlated with clinical manifestations.

Editorial comments: Sjogrens syndrome (SS), a chronic inflammatory disorder has a poorly understood etiology, as do many autoimmune diseases. This study echoes many of the findings that Dr. Behrens and others have found in the gene signatures of lupus patients mainly that interferon-inducible genes are upregulated in both diseases. It is not clear how these signatures differ between Sjogrens Syndrome and lupus. This must be further clarified. A strength of this study is its inclusion of clinical correlates to the gene signature.

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Abstract 1516: Gene Expression Profiling of Minor Salivary Glands in Primary Sjgrens Syndrome Clearly Groups Patients and Healthy Control Individuals
Trond O. Hjelmervik, Kjell Petersen, Inge Jonassen, Roland Jonsson, Anne Isine Bolstad.

Purpose: To investigate the gene expression profiles in patients with primary SS and healthy controls in order to find genes differentially expressed between the two groups.

Methods: A 13K cDNA microarray was used to generate profiles of gene expression in minor salivary glands of 10 primary SS patients and 10 controls. The data were analyzed with both parametric and non-parametric testing. The results were validated by running reverse transcription quantitative PCR (RT-QPCR) on five genes with significant differences between the two groups.

Results: A distinct difference in the expression profile was found, enabling a simple class prediction scheme to correctly classify 19 of the 20 samples as either patient or control based on the top 5 differentially expressed genes Among the 50 most highly expressed genes in the patient cohort , an obvious pattern of genes involved in chronic inflammation was observed. Fourteen major histocompatibility complex (MHC) genes were highly expressed (MHC class II, n = 8 and MHC class I, n = 6). Lymphocyte development and activation (n = 7, including NK activation gene and IL-6), antigen processing (n =4), signal transduction (n = 5, including STAT-1) and cell migration genes were also highly expressed. Additionally, the expression of carbonic anhydrase II (CA2) and lysosomal-associated membrane protein 1 (LAMP-1), essential in saliva production, were distinctly down-regulated in primary SS patients.

Highly Differentiated Expressed Genes

Conclusion: These investigators have identified a distinct gene expression profile which may be used to separate primary SS patients from healthy individuals, and possibly from patients with other chronic inflammatory disorders of salivary glands.

Editorial comment: These Norwegian investigators have proposed a unique gene expression profile that is clearly different from healthy controls and reproducible among the SS patients in the study. Interestingly, in opposition to Abstract 1123 reviewed above, interferon-inducible genes were not found to be among the top 50 candidate genes with the highest expression. Of note, the gene chip utilized in this study was a 13,000 gene microarray but was not an Affymetrix chip. The authors findings that gene expressed in chronic inflammation were up-regulated lend credence to the validity of their results. Distinction of patients with SS from healthy controls does not require genetic signatures for diagnostic purposes but may help determine therapeutic targets. Distinction of SS from other chronic inflammatory salivary diseases may have some clinical relevance. Additional exploration of genetic signatures between the latter two groups is warranted.

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Abstract 1510: Rituximab (anti-CD20) for the Treatment of Primary Sjogren's Syndrome
Justin Pijpe, Hendrika Bootsma, Gustaaf Van Imhoff, Arjan Vissink, Khaled Mansour, Jacqueline Van der Wal, Caroline Roozendaal, Philip Kluin, Fred Spijkervet, Jan Roodenburg, Cees Kallenberg.

Purpose: To investigate the safety and efficacy of rituximab in the treatment of patients with early, active primary Sjgrens syndrome (SS). In SS, high levels of B-cell auto reactivity are associated with high disease activity with development of systemic complications and an increased risk on the development of B-cell lymphoma (with a relative risk of 44). Rituximab , an anti- CD20 agent, effectively depletes B-cells, known to be pathogenic in SS.

Methods: Fifteen patients with primary SS were included in this phase I/II trial. Inclusion criteria included B-cell hyperactivity (IgG > 15g/l), presence of autoantibodies (IgM-Rheumatoid factor and anti-SSA/B), disease duration 4 years) and no use of immunosuppressive therapy. The patients were treated with 4 infusions of rituximab (375 mg/m2) weekly. The effect was evaluated by questionnaires, sialometrical/-chemical profile, lacrimal function, and serological parameters (ESR, IgG, FACS analysis on B- and T-cells). Finally, an incision biopsy of the same parotid gland was taken before and three months after treatment.

Results: Six patients (all female, mean age 50 years) were treated. Two patients developed a clinical picture compatible with serum sickness after the second infusion, and treatment was stopped. Preliminary data on clinical efficacy suggest marked improvement of subjective complaints (fatigue, sicca complaints and health status) and an increase in salivary gland function. Analysis of saliva showed a decrease in inflammatory activity. Lacrimal gland function was unchanged or slightly improved. Serological analysis demonstrated a decreased ESR and rheumatoid factor. Levels of IgG remained stable or decreased. Follow-up biopsies of the parotid gland demonstrated a decrease of IgG-producing B-cells in affected tissue.

Conclusions: The authors suggest that this open label phase I/II study suggests rituximab as a promising therapy in the treatment of patients with early onset primary SS. They contend that serum sickness in 2 out of 6 patients warrants further analysis. They anticipate conducting long-term follow-up in a controlled study to further investigate the therapeutic potential of rituximab.

Editorial Comment: Although there was a clinical response, the toxicity in one third of patients warrants close consideration. Serum sickness is not a common side effect of rituximab, suggesting that a closer look into the pathogenetic mechanism in this patient subset is necessary. Although current therapy including corticosteroids and hydroxychloroquine may be relatively ineffective for primary SS, one must consider whether this cure (rituximab) is worse than the disease in this case.

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