VIP alone did not modify the basal expression of apoptotic mediators or the condensation of chromatin in NOD and con trol acini. Discussion We presented evidence to indicate that acinar cells isolated from submandibular glands of NOD mice with salivary dys function are more sensitive to TNF induced apoptotic events than BALBc control cells and that VIP prevents these effects. We also showed that NOD acinar cells are functional for cAMP signalling and amylase secretion through VIP recep tors, although they express a number of apoptotic signals and mediators activated in resting conditions that were enhanced with TNF and prevented by VIP. Our conclusions are based on three main observations.
First, acinar cells isolated from submandibular glands of NOD mice undergoing salivary flow decline showed increased condensa tion of nuclear chromatin, caspase 3 activity and Bax, TNF R1 and TP53INP1 expression compared with control mice. Second, TNF enhanced apoptotic events in NOD acini at a concentration that did not modify various apoptotic mediators in BALBc selleck chemicals acini. However, the treatment of normal BALBc acinar cells with a higher TNF concentration reproduced the apoptotic pattern of resting NOD acini. Third, pretreatment of NOD acini with VIP acting on functional VPAC1 receptors prevented apoptotic events induced by TNF. Apoptosis mediated through FasFasL has already been reported in salivary glands of NOD and NOD scid mice with increased Fas expression in both acinar and ductal cells at 18 weeks of age. In contrast, FasL was detected as earlier as eight weeks in NOD submandibular glands.
Similarly, cas pase 3 gene expression appeared to be increased in sub mandibular glands of the Sjgrens syndrome susceptible strain C57BL6NOD. recommended you read Aec1Aec2 mice at eight weeks of age but returned to baseline values at the 12th week of age. This supports the notion that early defects in glandular home ostasis leading to apoptotic events might predispose them to the autoimmune response. Here we showed that acinar cells from NOD mice present a characteristic apoptotic pattern with increased Bax expres sion, chromatin condensation and caspase 3 activation adding new evidence to previously reported apoptosis markers in NOD whole gland samples and DNA fragmentation in NOD acinar suspension. The signs of apoptosis were detected in acinar cells from NOD mice at 16 weeks of age when they had already developed a saliva flow reduction higher than 40% compared with BALBc mice.
Of note, at eight weeks of age NOD females showed normal salivary func tion and there was no detectable apoptosis of acinar cells, suggesting that apoptotic processes, if present, might be incipient at this early stage and not detectable by the meth ods used. Among the pro apoptotic mediators determined in NOD aci nar cells, here we chose to analyse and TP53INP1 isoform expression.