VASOACTIVE INTESTINAL PEPTIDE INHIBITS TNF-ALPHA-INDUCED APOPTOTIC EVENTS IN ACINAR CELLS FROM NONOBESE DIABETIC MICE SUBMANDIBULAR GLANDS

MARIO CALAFAT, LUCIANA LAROCCA, VALERIA ROCA, VANESA HAUK, NICOLÁS PREGI, ALCIRA NESSE,

Arthritis Research & Therapy

BioMed Central Ltd.

Año: 2009 vol. 11 p. 1 - 10

1478-6354

Abstract Introduction The role of apoptotic secretory epithelium as a pro-inflammatory triggering factor of exocrine dysfunction is currently explored in Sjogren´s syndrome patients and in the nonobese diabetic (NOD) mouse model. Vasoactive intestinal peptide (VIP) has anti-inflammatory effects in various models of chronic inflammation. Our goal was to analyse the effect of TNF-alpha on apoptotic mediators in isolated acinar cells from NOD submandibular gland and their modulation by VIP. Methods Acinar cells were isolated from submandibular glands of 16-week-old NOD females with salivary flow decline. Agematched BALB/c females or eight-week-old NOD females were used as controls. Apoptotic mediators and TNF-alpha receptor expression were assessed by immunoblotting and RT-PCR, caspase 3 activity was assessed by optical density at 405 nm with Ac-DEVD-pNA as a substrate and chromatin condensation by Hoechst stain. They were evaluated in resting conditions and after a 3.5 or 6 hours of culture with TNF-alpha. VIP effects in acinar cells were assessed at 100 nM in TNF-alpha-treated cultures and VIP receptor functional assays by radio immunoassay (cAMP) or enzymatic detection (amylase). Results NOD acinar cells at 16 weeks present an increased expression of TNF-alpha receptor1 together with increased Bax, tumour protein 53-induced nuclear protein1alpha (TP53INP1alpha), caspase 3 activity and chromatin condensation. Acini from NOD mice were more sensitive to TNF-alpha-induced increases of apoptotic mediators than control cells. VIP inhibited TNF-á-induced apoptotic events through functional VPAC1 receptors coupled to the protein kinase A (PKA) signalling pathway. Conclusions Our results indicate that acinar cells isolated from submandibular glands of NOD mice with salivary dysfunction are more sensitive to apoptosis induced by TNF-alpha which could be prevented by VIP through a PKA-mediated pathway.