Intermittent fasting confers protections to various diseases including autoimmune disorders, but the specific effects of intermittent fasting on Sjögren’s syndrome (SS) remains inconclusive. The present study was undertaken to determine the specific impact of alternate-day fasting (ADF) on newly established SS-like sialadenitis using non-obese diabetic (NOD) mice. Female NOD mice were deprived of food every other day from 10 to 13 weeks of age, the early stage of established SS, and then analyzed for the disease characteristics. Mice in the ADF group had higher salivary flow rate and attenuated submandibular gland (SMG) inflammation, compared to the control mice fed with standard chow ad libitum. The improvements were accompanied with a decrease in the total leukocytes, T and B lymphocytes and activated CD4 and CD8 T cells, and a down-regulation of pro-inflammatory cytokines IFN-γ and IL-17, chemokine receptor CXCR3 and its ligands CXCL9 and CXCL11 in the SMGs. ADF also led to elevated mRNA levels of water channel protein aquaporin 5 and tight junction protein claudin-1, two factors crucial for normal salivary secretion in the SMGs. In addition, ADF reduced the proportion of IFN-γ- and IL-17- expressing CD4 T cells and diminished mRNA levels of IFN-γ, TNF-α, and IL-17 in the total submandibular draining lymph node cells. Taken together, ADF is effective in ameliorating newly established SS-associated salivary gland exocrinopathy in NOD mice.

Intermittent fasting confers protection in diverse diseases through various mechanisms, including the clearance of senescent and pathogenic cells, modulation of tissue inflammation and enhancement of stem/progenitor cell niche and functionality. Our previous study demonstrated the beneficial impact of alternate-day fasting (ADF) on xerostomia and sialadenitis, along with an improvement in salivary gland ductal compartments, where salivary gland progenitor cells reside, in non-obese diabetic mice, a spontaneous model of Sjögren’s syndrome (SS). In the present study, we induced SS-associated hyposalivation in KRT5^CreERT2; R26^tdTomato lineage tracing mice by immunizing them with submandibular gland proteins from wild-type C57BL/6 mice. ADF alleviated salivary gland hypofunction, which was accompanied by decreased expression of the senescent cell marker p16^INK4a, reduced protein levels of anti-apoptotic proteins BCL-2, BCL-XL, and MCL-1, and attenuated NLRP3 inflammasome activity in the submandibular glands, particularly within the ductal compartments, of this inducible model. Furthermore, immunofluorescence staining of submandibular gland sections revealed the expression of the acinar cell marker aquaporin 5 in a small subset of Keratin 5⁺ cells in 2 of 9 mice that were subjected to ADF, whereas no such cells were detected in the control mice. Taken together, these findings indicate that ADF favorably modulates the salivary gland progenitor cell niche, potentially by promoting apoptosis-mediated senescent cell clearance, suppressing NLRP3 inflammasome signaling, and promoting Keratin 5⁺ progenitor cell-derived acinar cell replenishment, thereby contributing to the structural and functional restoration of damaged salivary glands in autoimmune exocrinopathy.