Active vitamin D regulates macrophage M1/M2 phenotypes via the STAT‐1‐TREM‐1 pathway in diabetic nephropathy

Abstract

Aim: Imbalance of M1/M2 macrophages phenotype activation is a key point in diabetic nephropathy (DN). This study aimed to investigate whether active vitamin D (VD) suppresses macrophage transition to the M1 phenotype via inhibiting the high glucose-induced STAT-1 phosphorylation to reduce TREM-1 expression. Methods:In vivo, pathological changes in kidney tissue were detected and the expression of CD68 TREM-1, STAT-1, M1 makers, and M2 makers were acquired in renal tissue of patients with DN and 18w DN rats. In vitro, RAW 264.7 cells were incubated in the presence of high glucose with or without VD . Silencing and overexpression of TREM-1 and silencing and activate of STAT-1 were explored to elucidate the underlying mechanism.The expression of TREM-1 and STAT-1 and the changes of macrophage phenotype were examined separately by western blot and immunofluorescence staining. Results: (a) Expression of TREM-1, p-STAT-1, and M1 markers (iNOS and TNF-α) were increased and positively correlated in kidneys from patients with DN. (b) In DN rats, the enlargement of glomerular surface area, expansion of glomerular mesangial matrix, the expression of CD68, TREM-1, p-STAT-1, and M1 marker (iNOS) were significantly increased in comparison with the normal control group, whereas above changes were markedly decreased in the diabetic group treated with the VD group. (c) In vitro, VD significantly decreased high glucose-induced CD68, TREM-1, p-STAT-1, and M1 marker (iNOS) expression. However, above-mentioned effects of VD are abolished when TREM-1 is overexpressed or STAT-1 is activated. Reductions in STAT-1 expression decreased the TREM-1 expression. Conclusion: VD can inhibit macrophage transition to the M1 phenotype through the STAT-1/TREM-1 pathway. K E Y W O R D S active vitamin D, diabetic nephropathy, M1/M2 phenotype, macrophage, STAT-1, TREM-1

Extracellular vesicles produced by bone marrow mesenchymal stem cells attenuate renal fibrosis, in part by inhibiting the RhoA/ROCK pathway, in a UUO rat model

“…Immunofluorescence staining on renal paraffin sections was performed as described previously [18]. For CD34 and Col1α1 staining, paraffin-embedded sections were used.…”

“…For IHC staining, paraffin-embedded kidney sections were rehydrated and incubated in 10 mM SOD1ium citrate with 0.05% Tween for antigen retrieval [18]. After blocking, the sections were incubated with anti-α-SMA (ab5694), anti-Fibronectin (ab2413), anti-ED1 (ab31630), and anti-E-cadherin (20874-1-AP) at 4°C overnight, followed by incubation with a horseradish peroxidase-conjugated secondary antibody for 1 h at 37°C.…”

Polyphenol Supplementation Reverses Age-Related Changes in Microglial Signaling Cascades

“…Likewise, quercetin supplementation attenuated microgliainduced oligodendrocyte necroptosis via inhibition of Signal transducer and activator of transcription 1 (STAT1) and NF-κB pathways [62]. Finally, vitamin D 3 decreased iNOS expression in macrophages cultured from human and rat kidneys via a STAT1-TREM-1 (Triggering receptor expressed on myeloid cells)-mediated process [63]. Our pathway analysis demonstrates the age-related molecular changes in microglia protein signaling and the reversal of those changes with polyphenol supplementation.…”

Regulatory Effect of 1,25(OH)2D3 on TGF-β1 and miR-130b Expression in Streptozotocin-Induced Diabetic Nephropathy in Rats

“…The underlying mechanism is still unclear. Studies have shown that 1,25(OH)2D3 beneficially affects renal fibrosis in DN via TGF- β 1, signal transducer and activator of transcription 1, protein tyrosine phosphatase nonreceptor type 2, and Nrf2 [31–33]. Studies in animal models show that 1,25(OH)2D3 can inhibit TGF- β 1 and improve renal fibrosis in diabetic rats [5].…”