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.



Forty pSS patients and 20 sex- and age-matched healthy volunteers were included. Salivary cystatin S levels were assessed by western blot analysis using a stain-free technology. The expression of miR-126, miR-335-5p and cystatin S was assessed by quantitative PCR in 15 MSG biopsies differing for USFR and MSG focus score.



We found that salivary cystatin S was significantly decreased in pSS patients vs healthy volunteers ( P = 0.000), especially in those with hyposalivation. A positive correlation was observed between cystatin S and USFR ( r = 0.75, P = 0.01). Salivary cystatin S was also significantly reduced in patients with a submandibular gland ultrasonography score ⩾2. The expression levels of miR-126 and miR-335-5P increased in inverse proportion with USFR. The mRNA of cystatin S did not change significantly, suggesting post-transcriptional regulation.



Cystatin S emerged as a promising biomarker for pSS, strongly correlated with glandular dysfunction. An upregulation of miR-126 and miR-335-5P might be implicated in its expression.
Department of Clinical and Experimental Medicine, University of Pisa.
Daniela
D
Martini
Department of Laboratory Medicine and Advanced Biotechnologies, Istituto di Ricovero e Cura a Carattere Scientifico-Istituto Mediterraneo per i Trapianti e Terapie ad Alta Specializzazione (IRCCS- ISMETT), Palermo, Italy.
Alessia
A
Gallo
Department of Laboratory Medicine and Advanced Biotechnologies, Istituto di Ricovero e Cura a Carattere Scientifico-Istituto Mediterraneo per i Trapianti e Terapie ad Alta Specializzazione (IRCCS- ISMETT), Palermo, Italy.
Serena
S
Vella
Department of Clinical and Experimental Medicine, University of Pisa.
Francesca
F
Sernissi
Department of Clinical and Experimental Medicine, University of Pisa.
Antonella
A
Cecchettini
Department of Clinical and Experimental Medicine, University of Pisa.
Nicoletta
N
Luciano
Department of Clinical and Experimental Medicine, University of Pisa.
Enza
E
Polizzi
Department of Laboratory Medicine and Advanced Biotechnologies, Istituto di Ricovero e Cura a Carattere Scientifico-Istituto Mediterraneo per i Trapianti e Terapie ad Alta Specializzazione (IRCCS- ISMETT), Palermo, Italy.
Pier Giulio
PG
Conaldi
Department of Clinical and Experimental Medicine, University of Pisa.
Marta
M
Mosca
Department of Clinical and Experimental Medicine, University of Pisa.
Chiara
C
Baldini
D015415:Biomarkers / Q000378:metabolism; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D035683:MicroRNAs / Q000378:metabolism / Q000502:physiology; D008875:Middle Aged; D012463:Saliva / Q000378:metabolism; D055333:Salivary Cystatins / Q000378:metabolism*; D012859:Sjogren's Syndrome / Q000150:complications* / Q000378:metabolism; D013363:Submandibular Gland / Q000378:metabolism; D013364:Submandibular Gland Diseases / Q000209:etiology* / Q000378:metabolism
D015415:Biomarkers; C527111:MIRN126 microRNA, human; C556347:MIRN335 microRNA, human; D035683:MicroRNAs; D055333:Salivary Cystatins
Sjögren’s syndrome; cystatin S; miRNA; salivary proteomics