Impact of high salt diet on Sjögren’s syndrome and type 1 diabetes mellitus

Aim - investigate the potential role of local hyperosmolarity (HOS) and high salt diet (HSD) as (micro)environmental factor involved in Sjögren Syndrome and type-1 Diabetes Mellitus. 1. Identification of HOS-induced modulated immunoactive proteins (IMAP) expression dependent on NFAT5 activation in NS-SV-AC cells (human salivary gland cell line). NS-SV-AC cells will be subjected from 4 to 24h to isoosmolar or HOS stress and IMAP expressions will be quantified by RNAseq, Multiplex Elisa or Western blot. The HOS-modulated IMAP genes depending upon NFAT5 activation will be identified by use of dominant-negative NFAT5. 2. Impact of HSD on salivary glands, Th17/Treg lymphocytes, microbiome and microbial metabolites of NOD mice. 16-week-old female BALB/c mice (control) and NOD mice are subjected for 8 weeks to either control chow and tap water ad libitum or sodium-rich chow containing 4% NaCl and tap water containing 1% NaCl ad libitum (HSD group). Agonist-stimulated saliva flow and salivary Na+, K+ and Cl- concentrations will be determined as well as major salivary glands inflammatory infiltrates (assessed by histology), transcriptome (assessed by RNAseq) and IMAP expressions (by Multiplex ELISA or sqWB and immunofluorescence). Oral and caecal microbiome will be determined by metagenomics DNA sequencing. Caecal microbial metabolites will be identified by gas-chromatography-time of flight mass spectrometry. 3. Impact of NFAT5 knockdown and high salt diet on DMXAA-inducible SS. 8-week-old Cre+ NFAT5flx/flx mice will be fed with NSD or HSD and daily intraperitoneal injection of vehicle (used to solubilize tamoxifen, weeks 4-6) to validate and characterize the model as above. Afterwards implication of NFAT5 will be studied by daily intraperitoneal injection of tamoxifen (weeks 4-6) in the same model.