THBS1/CD47 Modulates the Interaction of γ-Catenin With E-Cadherin and Participates in Epithelial–Mesenchymal Transformation in Lipid Nephrotoxicity

Abstract

Hyperlipidemia, an important risk factor for cardiovascular and end-stage renal diseases, often aggravates renal injury and compromises kidney function. Here, histological analysis of human kidney samples revealed that high lipid levels induced the development of renal fibrosis. To elucidate the mechanism underlying lipid nephrotoxicity, we used two types of mouse models (Apoe−/− and C57BL/6 mice fed a 45 and 60% high-fat diet, respectively). Histological analysis of kidney tissues revealed high-lipid-induced renal fibrosis and inflammation; this was confirmed by examining fibrotic and inflammatory marker expression using Western blotting and real-time polymerase chain reaction. Oxidized low-density lipoprotein (OX-LDL) significantly induced the fibrotic response in HK-2 tubular epithelial cells. RNA-sequencing and Gene Ontology analysis of differentially expressed mRNAs in OX-LDL-treated HK-2 tubular epithelial cells and real-time PCR validation in Apoe−/− mice showed that the expression of thrombospondin-1 (THBS1) in the high-fat group was significantly higher than that of the other top known genes, along with significant overexpression of its receptor CD47. THBS1 knockdown cells verified its relation to OX-LDL-induced fibrosis and inflammation. Liquid chromatography tandem mass spectrometry and STRING functional protein association network analyses predicted that THBS1/CD47 modulated the interaction between γ-catenin and E-cadherin and was involved in epithelial–mesenchymal transition, which was supported by immunoprecipitation and immunohistochemistry. CD47 downregulation following transfection with small-hairpin RNA in OX-LDL-treated tubular epithelial cells and treatment with anti-CD47 antibody restored the expression of E-cadherin and attenuated renal injury, fibrosis, and inflammatory response in OX-LDL-treated cells and in type 2 diabetes mellitus. These findings indicate that CD47 may serve as a potential therapeutic target in long-term lipid-induced kidney injury.

Study on the effect of periodontitis on renal tissue in atherosclerotic mice

“…30,49 The prominent pathological manifestations in the AS and AS + PD groups may be related to the changes of blood lipids and inflammation induced by lipid metabolism disorders in mice after the occurrence of atherosclerotic lesions. 21,34 Previous studies have shown that kidney damage related to lipid metabolic disorders usually begins with structural changes of renal tubules, manifested by vacuolar degeneration, brush border destruction and exfoliation of cells, 50,51 which is consistent with our experimental results. The results of histopathological staining suggested that when periodontitis exists alone in mice, its effect on inducing renal tissue damage is limited, whereas renal tissue damage was severe in AS mice in comparison; when periodontitis occurred in AS mice, the pre-existing renal tissue damage in AS mice was significantly exacerbated, demonstrating that periodontitis significantly induced renal tissue damage in AS mice.…”

“…Therefore, in order to verify the above view and evaluate the effect of periodontitis on renal inflammation in AS mice, we detected three markers of renal inflammation, including TNF‐α, IL‐1β and Ly6G. As key proinflammatory cytokines, TNF‐α and IL‐1β are commonly used inflammatory markers, which play an important role in renal inflammation and kidney damage 17,21,46,47 . Especially, TNF‐α has been shown to play a central role in the structural and functional changes of the kidney associated with periodontitis and obesity 30 .…”

“…As key proinflammatory cytokines, TNFα and IL-1β are commonly used inflammatory markers, which play an important role in renal inflammation and kidney damage. 17,21,46,47 Especially, TNFα has been shown to play a central role in the structural and functional changes of the kidney associated with periodontitis and obesity. 30 Ly6G is a neutrophil surface marker, and neutrophils are a kind of immune inflammatory cells, and previous studies have shown that neutrophils have a very important role in the renal inflammatory response and kidney damage.…”

“…Previous studies have shown that CKD usually develops in the context of hypertension and dyslipidemia, 19 and scholars also proposed the “lipid nephrotoxicity” hypothesis as early as 1982, pointing out that disorders of lipid metabolism are involved in the progression of CKD 20 . Therefore, dyslipidemia is not only a consequence of CKD but also one of the causes of kidney damage 21 . AS is a degenerative vascular disease accompanied by a chronic and progressive inflammatory state characterized by a slow accumulation of lipid plaques and macrophages in large and medium‐sized arteries.…”

Single-cell RNA sequencing reveals rebalancing of immunological response in patients with periodontitis after non-surgical periodontal therapy

“…Thus, RESIS-TIN signaling may systemically increase susceptibility to diverse diseases. Moreover, the THBS network, whose ligand is highly expressed after LPS stimulation, increases the risk of inflammation [51,52], and the CD48 network, which is known to activate NK cells and contribute to diverse autoimmune diseases, is maintained even after periodontal therapy [53,54]. All this evidence indicates that typical periodontal treatment cannot be the sole strategy for complete immune recovery and necessitates consideration of other therapeutic approaches.…”