Autophagy occurs in lymphocytes infiltrating Sjögren’s syndrome minor salivary glands and correlates with histological severity of salivary gland lesions

Abstract

Backgrounds The organization of minor salivary glands (MSG) infiltrates, in patients with Sjögren’s syndrome (SS), associates with disease severity and progression. Aberrant regulation of lymphocyte autophagy is involved in autoimmunity, and in previous work, we provided the first evidence of upregulated autophagy in CD4+ T cells infiltrating SS MSG. The aim of this study was to further explore autophagy in SS infiltrating and circulating lymphocytes and to investigate its role in disease histopathological progression. Methods After collection of 20 SS MSG, the presence of lymphocyte aggregates (foci) and the formation of germinal center (GC)-like structures were observed by H&E and confirmed by immunohistochemistry. The expression of autophagy-related genes, Atg5 and MAP1LC3A, was detected by RT-PCR on microdissected salivary gland tissue and control tonsils. In MSG and tonsils, autophagic lymphocytes were identified by the detection of the autophagosome protein LC3B visualized as LC3 puncta staining by immunofluorescence. Peripheral blood autophagy was assessed by flow cytometry in SS and healthy controls (HC). Results Real-time PCR demonstrated higher expression in the autophagy genes Atg5 and MAP1LC3A in MSG GCs as compared to both small foci (p = 0.0075, p = 0.0002) and GCs from tonsils (p = 0.0001, p = 0.0037). In MSG, LC3 puncta staining was detectable on both CD3+ and CD20+ lymphocytes; in tonsils, LC3 puncta was almost undetectable on all lymphocytes. Compared to HC (n = 20), flow cytometry did not reveal any increase of autophagy in SS circulating lymphocytes (n = 30). Conclusions In SS MSG, lymphocytes’ autophagy is a feature of infiltrating T and B cells and is associated with histological severity. Interestingly, in MSG aberrant regulation of autophagy is detectable in GC-like structures possibly indicating its involvement in the development and persistence of the autoimmune process within the lesions.

Alterations of m6A RNA methylation regulators contribute to autophagy and immune infiltration in primary Sjögren’s syndrome

“…The pathologic role of autophagy in the lymphocyte infiltration of exocrine glands, as well as in the survival and activation of epithelial cells in the salivary gland has previously been described in pSS ( 3 ). Colafrancesco et al ( 3 , 40 , 41 ) demonstrated that up-regulated autophagy pathways induced by inflammation activate salivary gland epithelial cells in pSS, causing the high expression of adhesion molecules, and it is associated with histologic severity. This study discovered hub genes of autophagy in pSS, including PIK3CA, STAT1, MAPK3, and MTOR.…”

Maladaptive Autophagy in the Pathogenesis of Autoimmune Epithelitis in Sjögren's Syndrome

“…In previous studies, we have investigated autophagy in the pathogenesis of primary SS focusing on lymphocytes infiltrating minor SGs (38,39). In the present study, we investigated the role of autophagy in the survival and activation of SGECs, which represent the main constituent of the SG microenvironment and the pivot of “autoimmune epithelitis” in primary SS.…”

Tofacitinib Decreases Autophagy of Fibroblast-Like Synoviocytes From Rheumatoid Arthritis Patients

“…Autophagy flux was also measured by flow cytometry by using the Cyto-ID™ Autophagy Detection Kit (Enzo Life Science) as previously described ( Colafrancesco et al, 2020 ).…”

“…Autophagy flux was also measured by flow cytometry by using the Cyto-ID ™ Autophagy Detection Kit (Enzo Life Science) as previously described (Colafrancesco et al, 2020). Briefly, FLS were pelleted and then resuspended in DMEM without phenol red, supplemented with 10% FBS, and diluted Cyto-ID solution.…”