Ultrastructural study of Sjögren's syndrome-like disease in MRL/l mice

An immunohistochemistry-based study on aquaporin (AQP)-1, 3, 4, 5 and 8 in the parotid glands, submandibular glands and sublingual glands of Sjögren's syndrome mouse models chronically administered cevimeline

Cevimeline is a muscarinic agonist that promotes saliva secretion and is used to treat Sjögren's syndrome (SS), an autoimmune disorder in which the exocrine glands that produce saliva are destroyed. Cevimeline is thought to affect the composition of saliva in part by regulating the localization of aquaporins (AQPs). In this study, we investigated the effects of chronic Cevimeline administration in the salivary glands of SS mice on the immunohistochemical localization of aquaporin (AQP)-1, 3, 4, 5 and 8. We used Cevimeline-untreated SS mice, treated SS mice, discontinued SS mice and untreated normal mice. AQP-5 was found in the apical and lateral membranes of acinar cells in the parotid and submandibular glands of cevimeline-treated SS mice and untreated normal mice. Saliva secretion and AQP-5 localization were sustained in SS mice who were chronically administered Cevimeline and at four weeks after discontinuation. Unlike AQP-5, the localization of AQP-1, 3, 4 and 8 were not affected by Cevimeline administration. Our findings demonstrated that administration of Cevimeline maintains the proper localization of AQP-5 in the acinar cells of the salivary gland, which may promote salivation in chronically treated SS mice. Clinically, this suggests that chronic Cevimeline administration may be useful therapeutically for SS patients suffering from a decrease in saliva secretion by improving the disordered AQP-5 localization.

Effects of cevimeline on the immunolocalization of aquaporin-5 and the ultrastructure of salivary glands in Sjögren's syndrome model mice

Sjögren's syndrome (SS) is an autoimmune disorder whose main symptoms include xerostomia and dry eyes. It has been demonstrated that abnormal expression of aquaporin (AQP)-5 in the parotid and submandibular glands in SS model mice was corrected by cevimeline. In the present study, we orally administered cevimeline hydrochloride (cevimeline) to female MRL/l mice, which are widely used as a model for SS, to immunohistochemically investigate the localization of AQP-5 in the salivary glands. We also assessed the ultrastructure of acinar cells in the submandibular glands. AQP-5 was expressed in the apical and lateral cell membranes of acinar cells in the parotid and submandibular glands of normal mice, but not in the sublingual glands. In contrast, AQP-5 was expressed not only in the cell membranes in the apical domains but also in the cytoplasm in the SS model mice, indicating that the localization of AQP-5 was disordered in the SS model mice. After administration of cevimeline, AQP-5 was predominantly localized in the cellular apical domains of the acinar cells. Electron microscopy revealed that administration of cevimeline to the SS model mice and normal mice markedly reduced the number of secretory granules, increased the area of the rough endoplasmic reticulum, and expanded the intercellular gaps in the cells of the submandibular acini. Condensed vacuoles were also observed in the Golgi apparatuses, indicating that secondary enhancement of secretion and production of saliva had occurred. Consequently, the results of the present study demonstrate that the administration of cevimeline to the SS model mice increased salivary secretion in the submandibular glands. Furthermore, cevimeline transiently normalized the localization of AQP-5 expression in the parotid and submandibular glands.

Increased expression of beta-defensin-2 and -3 during the development of autoimmune sialoadenitis in MRL/lpr mice

beta-Defensins (BD) are small cationic antimicrobial peptides that produced principally in the epithelial cells of a number of organs. The present study analyzed the expression patterns of BD-1, -2, and -3 during the development of sialoadenitis in MRL/lpr mice. Submandibular glands were dissected from MRL/lpr mice at 4, 8, 10, 12, 14, and 16 weeks of age. The expression of mouse (m) BD-1, -2, and -3 mRNAs was examined by RT-PCR and quantified using TaqMan real-time RT-PCR. No significant differences in the level of expression of mBD-1 were observed among mice of different ages. The level of expression of mBD-2 was significantly higher at 16 weeks than at 4 or 8 weeks. The expression level of mBD-3 was highest in 14-week-old mice and was significantly higher than in 4-week or 16-week-old animals. Immunohistochemical staining showed that BD-3 was clearly localized in the ductal cells with variable intensities. In the center of the foci of lymphatic infiltration, ductal staining was faint or often not present. The results indicate that BD-2 and -3 may be upregulated during the development of autoimmune sialoadenitis.

[Cevimeline hydrochloride hydrate (Saligren capsule 30 mg): a review of its pharmacological profiles and clinical potential in xerostomia]

Cevimeline hydrochloride hydrate is a muscarinic receptor agonist with a chemical structure of a quinuclidine. Intraduodenal administration of cevimeline hydrochloride hydrate dose-dependently increased salivary secretion in normal mice and rats, two strains of autoimmune disease mice, and X-irradiated rats. The clinical efficacy of the cevimeline hydrochlide hydrate at 30 mg t.i.d. during 4 weeks has been demonstrated in double blind comparative study with placebo. In addition, its treatments in 52 weeks have increased salivary flow and improved subjective and objective symptoms of patients with xerostomia in Sjögren's syndrome.

Age-related alterations in IL-1beta, TNF-alpha, and IL-6 concentrations in parotid acinar cells from BALB/c and non-obese diabetic mice

IL-1beta, TNF-alpha, and IL-6 have been implicated in the destruction of parotid gland acinar cells (but not duct cells) in autoimmune sialoadenitis. Here we report the temporal alterations of these cytokines in parotid acinar cells that may lead to this specificity in cell death in the non-obese diabetic (NOD) mouse model for Sjögren's syndrome. Immunohistochemistry on paraffin sections of parotid gland from 5- and 10-week-old BALB/c and NOD mice confirmed the presence of many peri-acinar lymphoid nodules but few T-cells and macrophages between acinar cells. RT-PCR on enzymatically dispersed mouse parotid acinar cells (MPACs) showed no bands for CD3varepsilon, CD20, or F4/80 regardless of mouse strain or age. By ELISA, MPACs from 10-week-old NODs showed a small but highly significant (p<0.003) increase in IL-1beta and a large significant decrease (p<0.008) in IL-6 compared to 5-week-old NODs. Norepinephrine-stimulated amylase release from MPACs was not different regardless of mouse strain or age. These data show that alterations in acinar cell production of IL-1beta and IL-6 in aging NODs precede periductal lymphoid aggregates and acinar cell secretory dysfunction. (J Histochem Cytochem 48:1033-1041,2000)

(+/-)-cis-2-methylspiro[1,3-oxathiolane-5,3'-quinuclidine] hydrochloride, hemihydrate (SNI-2011, cevimeline hydrochloride) induces saliva and tear secretions in rats and mice: the role of muscarinic acetylcholine receptors

We investigated effects of (+/-)-cis-2-methylspiro[1,3-oxathiolane-5,3'-quinuclidine] hydrochloride, hemihydrate (SNI-2011, cevimeline hydrochloride), a rigid analogue of acetylcholine, on saliva and tear secretions in rats and mice to evaluate its therapeutical efficacy for xerostomia and xerophthalmia in patients with Sjogren's syndrome and X-ray exposure in the head and neck. Intraduodenal administrations of SNI-2011 increased saliva secretion in a dose-dependent manner at doses ranging from 3 to 30 mg/kg in normal rats and mice, two strains of autoimmune disease mice and X-irradiated saliva secretion defective rats. The salivation elicited by SNI-2011 was completely inhibited by atropine. A similar atropine-sensitive response was observed in tear secretion. In rat submandibular/sublingual gland membranes, [3H]quinuclidinyl benzilate (QNB) binding was saturable, and Scatchard plot analysis revealed a single population of binding sites with a Kd of 22 pM and a maximal binding capacity of 60 fmol/mg protein. The competitive inhibition curve of the [3H]QNB binding by SNI-2011 was obtained, and its dissociation constant value calculated from IC50 was 1-2 microM. These results suggest that SNI-2011 increases saliva and tear secretions through a direct stimulation to muscarinic receptors in salivary and lacrimal glands, and they suggest that SNI-2011 should be beneficial to patients with Sjögren's syndrome and X-ray exposure in the head and neck.

Immunocytochemical identification of HIV (p24) antigen in parotid lymphoid lesions

Antibodies to specific human immunodeficiency virus (HIV) polypeptides are important laboratory markers of HIV infection. We have used an antibody to the major structural gag protein p24 of HIV-1 virus to immunochemically localize this capsid antigen in lymphoid cells from seven of eight patients at risk for HIV infection and who presented with parotid lymphadenopathy and lymphoepithelial cysts of the parotid gland. A clinicopathological assessment of these two manifestations as they relate to HIV infection is also presented.