Abstract
It has been recently reported that telocytes, a stromal (interstitial) cell subset involved in the control of local tissue homeostasis, are hampered in the target organs of inflammatory/autoimmune disorders. Since no data concerning telocytes in minor salivary glands (MSGs) are currently available, aim of the study was to evaluate telocyte distribution in MSGs with normal architecture, non-specific chronic sialadenitis (NSCS) and primary Sjögren’s syndrome (pSS)-focal lymphocytic sialadenitis. Twelve patients with pSS and 16 sicca non-pSS subjects were enrolled in the study. MSGs were evaluated by haematoxylin and eosin staining and immunofluorescence for CD3/CD20 and CD21 to assess focus score, Tarpley biopsy score, T/B cell segregation and germinal center (GC)-like structures. Telocytes were identified by immunoperoxidase-based immunohistochemistry for CD34 and CD34/platelet-derived growth factor receptor α double immunofluorescence. Telocytes were numerous in the stromal compartment of normal MSGs, where their long cytoplasmic processes surrounded vessels and encircled both the excretory ducts and the secretory units. In NSCS, despite the presence of a certain degree of inflammation, telocytes were normally represented. Conversely, telocytes were markedly reduced in MSGs from pSS patients compared to normal and NSCS MSGs. Such a decrease was associated with both worsening of glandular inflammation and progression of ectopic lymphoid neogenesis, periductal telocytes being reduced in the presence of smaller inflammatory foci and completely absent in the presence of GC-like structures. Our findings suggest that a loss of MSG telocytes might have important pathophysiological implications in pSS. The specific pro-inflammatory cytokine milieu of pSS MSGs might be one of the causes of telocyte loss.
Highlights
Primary Sj€ogren’s syndrome is a systemic autoimmune disorder mainly affecting women during the fourth and fifth decades of life (9:1 female to male ratio) and characterized by chronic inflammation of exocrine glands leading to progressive functional impairment [1,2,3]
Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine
Telocytes were numerous in the stromal compartment of normal minor salivary glands (MSGs), where their long cytoplasmic processes surrounded vessels and formed an almost continuous layer encircling both the excretory ducts and the secretory units (Figs 2A and B, 3A, E and I)
Summary
Primary Sj€ogren’s syndrome (pSS) is a systemic autoimmune disorder mainly affecting women during the fourth and fifth decades of life (9:1 female to male ratio) and characterized by chronic inflammation of exocrine glands leading to progressive functional impairment [1,2,3]. Dendritic cells, vascular endothelial cells and pericytes, but an additional type of stromal cells with peculiar phenotypical features has been recently identified and characterized in human and animal tissues [11,12,13,14,15,16]. These cells, named telocytes (telos, i.e. provided with long-distance cell projections), display a small cell body and extremely long cytoplasmic processes (telopodes) with a moniliform aspect characterized by the combination of thin segments (podomers) and dilated regions (podoms) [13, 15, 16]. Taken the lack of data in normal and pSS MSG tissue, the aims of the present study were to evaluate telocyte distribution in MSGs with normal architecture, non-specific chronic sialadenitis (NSCS; i.e. presence of scattered lymphocyte aggregates that do not reach the number of 50 and cannot be classified as foci) and FLS [27] and to identify possible associations between telocyte patterns and the extent of glandular inflammation and lymphoid organization
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