Protective Effects of Two Safflower Derived Compounds, Kaempferol and Hydroxysafflor Yellow A, on Hyperglycaemic Stress-Induced Podocyte Apoptosis via Modulating of Macrophage M1/M2 Polarization

Abstract

Objective. The primary initiating mechanism in diabetes nephropathy (DN) is hyperglycemia-induced inflammation in which macrophage and podocyte play important roles. The present research is aimed at exploring the effects of kaempferol (Ka) and hydroxysafflor yellow A (HSYA) on classically activated (M1)/alternatively activated (M2) macrophage polarization and podocyte apoptosis under hyperglycaemic conditions in vitro. Methods. (1) RAW264.7 cells were treated with 11.1 mM glucose (NG), 33.3 mM glucose (HG), Ka 4–8 μM, and HSYA 100–200 μM separately. The expressions of inducible nitric oxide synthase (iNOS), tumor necrosis factor- (TNF-) α, mannose receptor (CD206), and arginase- (Arg-) 1 were quantified by Western blotting and real-time quantitative PCR. The collected supernatants from macrophage were named as (NG) MS, (HG) MS, (Ka) MS, and (HSYA) MS. (2) The podocyte survival rate was assessed by Bromodeoxyuridine assay, while TNF-α and interleukin- (IL-) 1β levels were evaluated by Elisa. Results. (1) Compared to the HG group, the Ka and HSYA 100 μM groups decreased iNOS and TNF-α levels and increased Arg-1 and CD206 expressions significantly (protein and mRNA: p<0.05, respectively). (2) The podocyte survival rate of Ka 8 μM was higher than that of HG, and the rates of (Ka) MS and (HSYA 100 μM) MS were higher than that of (HG) MS significantly (all: p<0.05). (3) TNF-α and IL-1β levels of Ka and HSYA 100 μM were significantly lower than those of the HG group, and both levels in the (Ka) MS and (HSYA) MS were lower than those in the (HG) MS group significantly (p<0.05, respectively). Conclusion. The protective effects of Ka and HSYA on podocyte apoptosis under hyperglycemic stress are related to their modulation on M1/M2 polarization and the lowering effects on TNF-α and IL-1β levels.

Pharmacological Actions, Molecular Mechanisms, Pharmacokinetic Progressions, and Clinical Applications of Hydroxysafflor Yellow A in Antidiabetic Research

“…MPC-5 cell line is also widely used to evaluate renal injury in vitro [ 23 ]. Related research showed that HG-induced apoptosis of podocytes and pancreatic β -cells was reversed by HSYA [ 14 , 18 ].…”

“…For both diabetic wounds and DN progression, a central feature is the persistence of chronic inflammation, which is partly due to the prolonged presence of proinflammatory macrophages [ 25 , 26 ]. In HG- and lipopolysaccharide- (LPS-) induced RAW264.7 macrophage cells, HSYA showed its anti-inflammatory effects by decreasing TNF- α , IL-1 β , and nitric oxide (NO) levels [ 14 , 17 ]. From Table 1 , we could see that the main antidiabetic mechanism of HSYA is through its anti-inflammatory activity.…”

“…So far, our review has shown that the antidiabetic mechanisms of HSYA are related to the following signals: c-jun NH2-terminal kinases/c-jun (JNK/c-jun) pathway [ 18 ], NOX4 pathway [ 19 ], macrophage polarization [ 14 ], and phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) pathway [ 13 ]. HSYA also showed its ability to cause a decrease in oxidative stress factors such as ROS [ 18 , 19 ] and hydrogen peroxide (H 2 O 2 ) [ 19 ].…”

“…In Vitro Antidiabetic Research. In vitro antidiabetic studies were conducted on seven different cell lines: rat INS-1 insulinoma cells [18], mice MPC-5 podocyte cells [14], human umbilical vein endothelial cells (HUVECs) [17,19], human brain microvascular endothelial cells (HBMECs) [20], 3T3-L1 preadipocytes and adipocytes [21], and RAW264.7 macrophage cells [14,17].…”

“…Related research suggested that HSYA could inhibit the apoptosis of pancreatic β -cells, and this might be the underlying mechanisms through which HSYA regulates glycolipid metabolism in T2DM rats [ 13 ]. Our previous study indicated that HSYA had direct protective effects on high glucose- (HG-) induced podocyte injury and indirect protective effects by regulating macrophage M1/M2 polarization [ 14 ]. These effects were related to its antioxidant and anti-inflammatory activities in vitro [ 15 ].…”