Cystatin S-a candidate biomarker for severity of submandibular gland involvement in Sjögren's syndrome

Salivary cystatin S is a defence protein mainly produced by submandibular glands and involved in innate oral immunity. This study aimed to verify whether cystatin S was diversely expressed in different disease subsets of primary Sjogren's syndrome (pSS) patients, defined on the basis of salivary flow [unstimulated salivary flow rate (USFR)], minor salivary gland (MSG) focus score and submandibular gland ultrasonography abnormalities. We also evaluated miR-126 and miR-335-5p expression in MSG biopsies to verify whether an aberrant regulation of cystatin S at the glandular level may influence its salivary expression.