Background/Purpose: Sjögren’s syndrome (SS) is an immune-mediated exocrinopathy, where defects in autophagy could contribute to the pathogenesis. Minor labial salivary glands (MLSG) of primary SS (pSS) patients show increased IL-6 levels, JAK/STAT activation and decreased expression of autophagy markers, such as ATG5 and Beclin-1. Additionally, autophagy activation has been related with a reduced inflammatory response, although this is a controversial topic. Interestingly, activation of the IL-6/JAK/STAT3 pathway inhibits autophagy through increased MCL-1 expression in human small airway epithelial cells¹. The aim of this study was to determine inflammatory markers expression in autophagy-deficient salivary epithelial cells stimulated with or without IL-6. Finally, inflammatory markers expression relying on JAK/STAT signalling pathway was inhibited using tofacitinib.

Methods: Immortalized human submandibular gland (HSG) cell line were transduced with lentiviral ATG5 shRNA-expressing vector (shATG5), and with an empty lentiviral vector used as negative control. The protein levels of ATG5, p62 and LC3B were determined in shATG5 and control cells. The mRNA levels of IL-6, IL-1β, IL-8, MCL-1 and CCL2 were measured by qPCR in control and autophagy deficient HSG cells. Subsequently, 3D-acini were generated from shATG5 and control cells, incubated with 10 ng/mL recombinant IL-6 (with/without tofacitinib) for 24h to measure MCL-1 and IL-6 (both STAT3 target genes) mRNA levels by qPCR.

Results: Increased IL-6, IL-1β and IL-8 mRNA levels was observed in shATG5 cells compared to control cells. Upregulation of these mRNA was observed with IL-6 stimulation and reversed by tofacitinib. Moreover, p62 protein levels increased and LC3B decreased in shATG5 cells, confirming our previous findings in MLSG from pSS patients. Interestingly, overexpression of mRNA levels of MCL-1, an autophagy inhibitor, was observed with IL-6 stimulation, but reversed in the presence of tofacitinib.

Conclusion: Our findings showed that decreased autophagy increases inflammatory markers expression in HSG cells. Tofacitinib inhibits the inflammatory effect of decreased autophagy, probably through the blocking of IL-6/JAK/STAT3 pathway, having a potential therapeutic effect in SS. More information is needed to establish the contribution of autophagy to SS pathogenesis and its role as a therapeutic target.

1. Cancer Res. 2014 Jul 15; 74(14): 3740–3752.

Fondecyt-Postdoctoral Grant-3170023, Fondecyt-1160015, Fondecyt-Iniciación-11170049.

« Back to 2019 ACR/ARP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/tofacitinib-inhibits-increased-inflammatory-marker-expression-in-a-human-salivary-cell-line-deficient-in-autophagy-a-model-of-sjogrens-syndrome/