Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA.
Department of Ophthalmology, Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA.
Sci Rep. 2020 Jan 29;10(1):1455. doi: 10.1038/s41598-020-58337-4.
Autoimmune dacryoadenitis and altered lacrimal gland (LG) secretion are features of Sjögren's syndrome (SS). Activity of cathepsin S (CTSS), a cysteine protease, is significantly and specifically increased in SS patient tears. The soluble chemokine, CX3CL1 (fractalkine), is cleaved from membrane-bound CX3CL1 by proteases including CTSS. We show that CX3CL1 is significantly elevated by 2.5-fold in tears (p = 0.0116) and 1.4-fold in LG acinar cells (LGAC)(p = 0.0026) from male NOD mice, a model of autoimmune dacryoadenitis in SS, relative to BALB/c controls. Primary mouse LGAC and human corneal epithelial cells (HCE-T cells) exposed to interferon-gamma, a cytokine elevated in SS, showed up to 9.6-fold (p ≤ 0.0001) and 25-fold (p ≤ 0.0001) increases in CX3CL1 gene expression, and 1.9-fold (p = 0.0005) and 196-fold (p ≤ 0.0001) increases in CX3CL1 protein expression, respectively. Moreover, exposure of HCE-T cells to recombinant human CTSS at activity equivalent to that in SS patient tears increased cellular CX3CL1 gene and protein expression by 2.8-fold (p = 0.0021) and 5.1-fold (p ≤ 0.0001), while increasing CX3CL1 in culture medium by 5.8-fold (p ≤ 0.0001). Flow cytometry demonstrated a 4.5-fold increase in CX3CR1-expressing immune cells (p ≤ 0.0001), including increased T-cells and macrophages, in LG from NOD mice relative to BALB/c. CTSS-mediated induction/cleavage of CX3CL1 may contribute to ocular surface and LG inflammation in SS.
自身免疫性泪腺炎和泪腺分泌改变是干燥综合征 (SS) 的特征。组织蛋白酶 S (CTSS) 的活性，一种半胱氨酸蛋白酶，在 SS 患者的泪液中显著且特异性增加。可溶性趋化因子 CX3CL1（ fractalkine）通过包括 CTSS 在内的蛋白酶从膜结合的 CX3CL1 上裂解。我们表明，与 BALB/c 对照相比，男性 NOD 小鼠（SS 自身免疫性泪腺炎的模型）的泪液中 CX3CL1 显著升高 2.5 倍（p=0.0116），LG 腺泡细胞 (LGAC) 中升高 1.4 倍（p=0.0026）。与 BALB/c 对照相比，暴露于干扰素-γ（一种在 SS 中升高的细胞因子）的原代小鼠 LGAC 和人角膜上皮细胞 (HCE-T 细胞) 的 CX3CL1 基因表达分别增加高达 9.6 倍（p≤0.0001）和 25 倍（p≤0.0001），CX3CL1 蛋白表达分别增加 1.9 倍（p=0.0005）和 196 倍（p≤0.0001）。此外，HCE-T 细胞暴露于活性相当于 SS 患者泪液的重组人 CTSS 可使细胞内 CX3CL1 基因和蛋白表达分别增加 2.8 倍（p=0.0021）和 5.1 倍（p≤0.0001），同时增加培养介质中的 CX3CL1 增加 5.8 倍（p≤0.0001）。流式细胞术显示，与 BALB/c 相比，NOD 小鼠的 LG 中表达 CX3CR1 的免疫细胞（包括 T 细胞和巨噬细胞）增加了 4.5 倍（p≤0.0001）。CTSS 介导的 CX3CL1 的诱导/裂解可能导致 SS 中的眼表和 LG 炎症。
