In line with this, labial biopsies and acinar cell primary cultures from SS patients show an aberrant expression and activation of inflammatory LY294002 mediators in epithelial cells together with defective activity and localization of key enzymes and channels involved in saliva secretion [5–8]. This observation supports the hypothesis that acinar cells are involved actively in the pathogenesis of SS and provides new evidence to the search of early biomarkers for diagnosis and/or disease activity. At the prediabetic stage, the non-obese diabetic (NOD) mouse model of Sjögren’s syndrome has the

unique characteristic of developing a deep secretory dysfunction with mild infiltration of the glands [9–11] consistent with a structural–dysfunctional aetiology. In keeping with this, early neurotransmitter receptor-signalling alterations have been reported in NOD females’ submandibular glands unrelated to the onset of the autoimmune response [12–14]. Among them, a progressive loss of activity of the neural isoform of nitric oxide synthase (NOS 1) in NOD exocrine glands at the Sjögren’s syndrome-like period has been described

[12,15]. The lower levels of NOS activity were found in glands of 16-week-old NOD mice that presented increased apoptosis of acinar cells and increased levels of tumour necrosis factor (TNF)-α, among other T helper type 1 (Th1) cytokines in the serum [15,16]. Vasoactive intestinal peptide (VIP), described initially as a vasodilator and prosecretory neuropeptide, has trophic effects on acini [17,18] and strong anti-inflammatory properties in Cobimetinib several models of chronic inflammatory diseases [19–21]. Prediabetic NOD mice treated systemically with VIP showed increased serum interleukin (IL)-10 and reduced Th1 cytokine levels very [22] while gene-transfer of VIP onto NOD submandibular

glands prevented saliva secretion loss and partly reduced glandular Th1 cytokine expression [23]. Furthermore, VIP showed a clear anti-apoptotic effect on acinar cells isolated from NOD submandibular glands driven to apoptosis through TNF-α/TNF-αR1-mediated pathways [16]. An adequate balance of apoptosis of epithelial cells and their silent clearance by professional phagocytes is central for gland homeostasis. On this basis, we hypothesized that the local expression of VIP/VPAC system could modulate acinar cell apoptosis and clearance, thus influencing gland homeostasis. We present evidence on a progressive decline of VIP expression in submandibular glands of NOD mice that encompasses a loss of acinar cells through apoptotic mechanisms. We also show that apoptotic acinar cells are removed by NOD macrophages with a reduced phagocytic efficacy compared to control macrophages, although in a suppressor manner that is stabilized by VIP.