Temporal changes in salivary glands of non-obese diabetic mice as a model for Sjögren's syndrome.

OBJECTIVE: Non-obese diabetic (NOD) mice develop an autoimmune exocrinopathy that shows similarities with Sjögren's syndrome. They provide an experimental model to study the pathoetiogenesis of this disease. MATERIALS AND METHODS: Salivary gland (SG) function and salivary sodium content were measured in 8-, 12-, 16- and 20-week-old NOD and age-matched CB6 mice. In NOD mice, SG expression of phenotypic cell markers, B cell-stimulating and costimulatory molecules were evaluated. Cytokine levels were measured in serum and SG homogenates. RESULTS: Microscopically evident SG inflammation in NOD mice was preceded by expression of intercellular adhesion molecule 1 on epithelial cells in the presence of macrophages and relatively high levels of cytokines. Next, an influx consisting of mainly T, B, natural killer, plasma and dendritic cells was seen. Most cytokines, except for interleukin (IL)12/IL23p40 and B cell-activating factor, decreased or remained stable over time, while glandular function deteriorated from 16 weeks of age onward compared with CB6 mice. CONCLUSION: Sjögren's syndrome-like disease in NOD mice occurs in multiple stages; immunological and physiological abnormalities can be detected before focal inflammation appears and salivary output declines. Extrapolating this knowledge to human subjects could help in understanding the pathogenesis and aid the identification of potential therapeutic targets.

NOD mouse model for Sjögren's syndrome: lack of longitudinal stability.

OBJECTIVES: The non-obese diabetic (NOD) mouse is not only a widely used model for diabetes mellitus type I, but also for the chronic autoimmune disease Sjögren's syndrome (SS), mainly affecting salivary and lacrimal glands. We studied the efficacy of local recombinant serotype 2 adeno-associated viral (rAAV2) vector transfer of immunomodulatory transgenes to alter the SS-like disease in NOD mice. Data collected over a 2-year period indicated a changing SS phenotype in these mice and this phenomenon was investigated. METHODS: 10(10) particles rAAV2LacZ/gland were delivered to both submandibular glands (SMGs) of NOD/LtJ mice at 8 weeks (before sialadenitis onset) of age. Salivary flow rates were determined at 8 weeks and time of killing. Blood glucose levels and body weights were measured weekly. After killing, saliva and SMGs were harvested. Analyses of salivary output, inflammatory infiltrates (focus score), SMG cytokine profile, body weight, and diabetes mellitus status were performed. Data from six different experimental studies over 2 years were analyzed and compared. RESULTS: Salivary flow rate, focus score, and SMG cytokines interleukin (IL)-2, IL-4, IL-6, IL-10, IL-12(p70), tumor necrosis factor-alpha and IFNgamma showed changes over time. There were no differences for body weight, diabetes mellitus prevalence, or blood glucose level of non-diabetic mice. CONCLUSION: This retrospective report is the first to describe longitudinal variability in the NOD mouse as a model for SS. We advise other investigators to continuously monitor the SS phenotype parameters and include appropriate controls when studying this disease in NOD mice.

Experience with experimental biological treatment and local gene therapy in Sjogren's syndrome: implications for exocrine pathogenesis and treatment.

Sjögren's syndrome is an autoimmune exocrinopathy, mainly affecting the lacrimal and salivary glands, and resulting in ocular and oral dryness (keratoconjunctivitis sicca and xerostomia). The aetiology and pathogenesis are largely unknown, and only palliative treatment is currently available. Data obtained from experimental animal and human studies using biological agents or gene therapeutics can offer insight into the disease process of Sjögren's syndrome. This article reviews the current literature on these approaches and assesses the lessons learnt about the pathogenesis of Sjögren's syndrome.

Effect of human vasoactive intestinal peptide gene transfer in a murine model of Sjogren's syndrome.

BACKGROUND: Sjögren's syndrome (SS), an autoimmune exocrinopathy mainly affecting lachrymal and salivary glands, results in ocular and oral dryness (keratoconjunctivitis sicca and xerostomia). The aetiology and pathogenesis are largely unknown; currently, only palliative treatment is available. OBJECTIVE: To determine whether gene transfer of vasoactive intestinal peptide (VIP), based on its immunomodulatory properties, might be useful in the management of SS. METHODS: A recombinant serotype 2 adeno-associated virus encoding the human VIP transgene (rAAV2hVIP) was constructed and its efficacy tested in the female non-obese diabetic (NOD) mouse model for SS after retrograde instillation in submandibular glands (SMGs). 10(10) particles/gland of rAAV2hVIP or rAAV2LacZ (encoding beta-galactosidase; control vector) were administered at 8 weeks of age (before sialadenitis onset). Salivary flow rates were determined before vector delivery and at time of death (16 weeks). After death, saliva, serum, and SMGs were harvested. Salivary output, inflammatory infiltrates (focus scores), VIP protein expression, cytokine profile, and serum anti-VIP antibodies were analysed. RESULTS: rAAV2hVIP significantly improved the salivary flow, increased SMG and serum expression of VIP, and reduced SMG cytokines interleukin (IL) 2, IL10, IL12 (p70), and tumour necrosis factor alpha, and serum RANTES, compared with the control vector. No difference in focus scores or apoptotic rates was found; neutralising antibodies were not detected. CONCLUSIONS: Local delivery of rAAV2hVIP can have disease modifying and immunosuppressive effects in SMGs of the NOD mouse model of SS. The new strategy of employing VIP prophylactically may be useful for both understanding and managing the salivary component of SS.

Rapamycin control of transgene expression from a single AAV vector in mouse salivary glands.

Salivary glands (SGs) appear to be a useful target site for gene therapeutics. The ability to control transgene expression is essential for clinical application. Previously, in a proof-of-concept study, we have shown that the rapamycin-inducible transcriptional regulation system can regulate protein expression after adenoviral-mediated gene transfer to SGs. To evaluate the potential ability to utilize this regulatory system for long-term control of transgene expression in this tissue, we employed a 'third generation', single adenoassociated serotype 2 viral (AAV2) vector encoding human erythropoietin (hEPO) under the control of a rapamycin-inducible promoter. The vector, rAAV-TF2.3-hEPO (10(10) particles/animal), was delivered to mouse SGs. No detectable increase in serum hEPO or hematocrit levels was observed in the absence of rapamycin administration. However, rapamycin induced elevation of serum hEPO levels, as well as concomitant hematocrit changes, that were dose-dependent, completely reversible, and relatively stable over the course of this study (6 months), with no appreciable change in rapamycin responsiveness. Our results suggest that the rapamycin transcriptional regulation system delivered in a single AAV2 vector to SGs may be valuable for systemic protein replacement applications.

Serum lipid levels in Sjögren's syndrome.

OBJECTIVES: Altered lipid levels may occur in autoimmune diseases, for example low cholesterol levels have been described in rheumatoid arthritis (RA). Serum lipid profiles in patients with Sjögren's syndrome (SS) have not been investigated. We hypothesized decreased lipid levels in SS patients and an inverse relationship with disease activity. METHODS: Serum lipid levels [total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL) and triglycerides] and additional data regarding disease measures (clinical immunology parameters, focus score from labial salivary gland biopsy, salivary flow and ophthalmological measures) were available for 46 primary SS patients and 12 xerostomic controls. RESULTS: Significant differences between SS patients and controls means (s.d.) were seen for HDL (P = 0.04) and total cholesterol (P = 0.02). LDL (P = 0.12) and triglyceride (P = 0.08) levels were not different. In SS patients, but not in controls, total cholesterol (P = 0.003) and HDL cholesterol (P = 0.003) predicted immunoglobulin G levels. Anti-SSA antibodies were related to a lower total cholesterol (P = 0.02) and anti-SSB antibodies to a lower HDL cholesterol level (P = 0.0497). CONCLUSIONS: Significant differences were seen in serum lipid levels of primary SS patients and these were associated with serological measures of inflammation. Our results are comparable to earlier findings in RA patients and raise questions related to adverse cardiovascular consequences in SS.

Adult heart block is associated with disease activity in primary Sjögren's syndrome.

OBJECTIVES: Congenital heart block occurring in the foetus and neonate may be associated with maternal anti-SS-A/anti-SS-B autoantibodies (anti-SSA/anti-SSB). The adult atrioventricular node is generally thought to be resistant to the damaging effects of anti-SSA/anti-SSB. However, case reports suggest that heart block developing in adult Sjögren's syndrome (SS) patients may be associated with these autoantibodies. Therefore, we investigated the relationship between serum antibodies and heart block in adult SS patients. METHODS: We abstracted data from clinic patient records. Diagnosis of primary SS was based on American-European classification criteria. Electrocardiograms (EKGs), laboratory immunology parameters, lipid profiles, and focus scores from labial salivary gland biopsies were available for 51 SS patients. Fifteen patients had follow-up EKGs. PR interval200 ms was considered to be first-degree heart block. RESULTS: Five patients showed prolonged PR intervals; the presence of heart block was not related to the presence of anti-SSA antibodies. However, significant differences between patients with prolonged and normal PR intervals were seen for mean focus scores (p<0.0001), anti-cardiolipin immunoglobulin IgG (p = 0.0009), age (p = 0.01), IgG (p = 0.02), anti-SSB antibodies (p = 0.02), and high density lipoprotein (HDL) cholesterol levels (p = 0.03). These parameters correlated with prolonged PR intervals. CONCLUSIONS: These results suggest an association between disease activity, the presence of anti-SSB antibodies, and the occurrence of first-degree heart block in adults with primary SS.

A recombinant adenoviral vector encoding functional vasoactive intestinal peptide.

Vasoactive intestinal peptide (VIP) is a small neuropeptide, which exerts pleiotropic functions. Based on its immunomodulatory, secretory, and possibly trophic effects, VIP is a valuable candidate molecule for the management of autoimmune disease. The purpose of this study was to develop a recombinant viral vector capable of directing the expression of functional VIP. The vector rAd5CMVhVIP was constructed and used to infect 293 cells. VIP expression was measured by an ELISA and function was evaluated by measurement of intracellular cAMP formation. rAd5CMVhVIP directed VIP expression and the transgenic VIP elicited a dose-dependent increase of intracellular cAMP, mediated through the VIP receptor VPAC(1). This is the first report showing the construction of a recombinant viral vector encoding biologically active VIP.