Adipose-derived stem cells postpone the progression of Sjögren's syndrome by upregulating the Hippo signaling pathway

Abstract

The aim of the present study was to explore the effect and mechanism of action of adipose-derived stem cells (ADSCs) on Sjögren syndrome (SS) to develop novel and more effective methods for SS treatment. ADSCs, dexamethasone or normal saline was injected into the submandibular gland (SMG) of three 12-week-old non-obese diabetic (NOD) mice. The degree of lymphocyte infiltration was considered as a criterion for judging disease progression, hematoxylin and eosin staining was performed to observe the pathological state, and the expression levels of TAZ, E-cadherin and α-catenin were assessed by western blotting. ADSC transplantation triggered an inhibitory effect on the progression of SS, which was slightly stronger compared with that of dexamethasone treatment. This was found to be related to the Hippo signaling pathway. In addition, TAZ protein expression levels decreased gradually with the progression of the disease; immunofluorescence staining showed that the expression of E-cadherin and TAZ followed similar trends. Notably, the expression of TAZ, p-TAZ, E-cadherin and α-catenin in NOD mice were lower compared with that in Control mice. Similarly, the ratio of p-TAZ/TAZ also decreased, which means that the activation level of Hippo signal pathway decreased. The results suggest that ADSCs may exert a therapeutic effect against SS and may postpone its progression by upregulating the Hippo signaling pathway.

Keywords: Hippo signaling pathway; Sjögren's syndrome; adipose-derived stem cell.

Figure 1

Sjögren's syndrome occurrence is accompanied by a downregulation of the Hippo signaling pathway. Western blotting analysis showed that the protein expression levels of E-cadherin, α-catenin, p-TAZ and TAZ were higher than those of SMGs in 17-week-old NOD mice. ^*P<0.05 vs. Control. E-cad, E-cadherin; NOD, non-obese diabetic; p-, phosphorylated; TAZ, transcriptional coactivator with PDZ-binding motif.

Figure 2

ADSCs may delay the infiltration of lymphocytes and thus Sjögren's syndrome progression. (A) NOD mice were randomly divided into Control (PBS-), DEX- and ADSC-treatment groups (n=15 mice/group). (B) Hematoxylin and eosin staining showed that, between 13 and 17 weeks, the degree of lymphocyte infiltration in SMGs of NOD mice in the ADSC group (B1-B5) was significantly lower compared with the Control group (A1-A5), whereas the degree of lymphocyte infiltration in SMGs of NOD mice in the DEX group (C1-C5) was between the two. (C) At the same time, the number of LAs in the different groups was detected (black rectangles in B) and counted. ^*P<0.05 vs. 13 weeks. ADSCs, adipose-derived stem cells; DEX, dexamethasone; LA, lymphocyte aggregate; NOD, non-obese diabetic; SMG, submandibular gland.

Figure 3

ADSCs delay the progression of Sjögren's syndrome by upregulating the Hippo signaling pathway. (A) Western blotting analysis showed that the protein expression levels of TAZ in the ADSC group and Control group decreased gradually between 13 and 17 weeks, and that the downward trend of TAZ in the ADSC group was slower compared with the Control group. (B) Immunofluorescence staining showed that the expression of E-cad (green) in SMGs from mice in the ADSC group was significantly higher compared with that in the Control group. DAPI (blue) was used to stain the nucleus. (C) Immunofluorescence showed that the expression of TAZ in SMGs of ADSC group was significantly higher than that of the Control group. DAPI (blue) was used to stain the nucleus. ^*P<0.05, ^**P<0.01. ADSCs, adipose-derived stem cells; E-cad, E-cadherin; SMG, submandibular gland; TAZ, transcriptional coactivator with PDZ-binding motif.

Figure 4

Knocking down the expression of TAZ reduces the postponing effect of ADSCs on SS. (A) shRNA lentivirus vector targeting TAZ was injected into tail vein of NOD mice (with ADSCs treated). (B) The expression of TAZ decreased after lentivirus transfection in SMGs in mice. ^*P<0.05, ^#P<0.05 vs. sh-NC. (C) Knocking down TAZ reduced the delaying effect of ADSCs on SS, but this effect is still stronger than the PBS-treated Control group. ^*P<0.05; ^#P<0.05. ADSCs, adipose-derived stem cells; NOD, non-obese diabetic; sh, short hairpin RNA; SMG, submandibular gland; SS, Sjögren's syndrome; TAZ, transcriptional coactivator with PDZ-binding motif.

Figure 5

A brief schematic diagram of this study. NOD, non-obese diabetic; ADSCs, adipose-derived stem cells; E-cad, E-cadherin; TAZ, transcriptional coactivator with PDZ-binding motif.