IGF-1 inhibits inflammation and accelerates angiogenesis via Ras/PI3K/IKK/NF-κB signaling pathways to promote wound healing

Exogenous insulin-like growth factor-1 (IGF-1) has been reported to promote wound healing through regulation of vascular endothelial cells (VECs). Despite the existing studies of IGF-1 on VEC and its role in angiogenesis, the mechanisms regarding anti-inflammatory and angiogenetic effects of IGF-1 remain unclear. In this study, we investigated the wound-healing process and the related signaling pathway of IGF-1 using an inflammation model induced by IFN-γ. The results demonstrated that IGF-1 can increase cell proliferation, suppress inflammation in VECs, and promote angiogenesis. In vivo studies further confirmed that IGF-1 can reduce inflammation, enhance vascular regeneration, and improve re-epithelialization and collagen deposition in acute wounds. Importantly, the Ras/PI3K/IKK/NF-κB signaling pathways was identified as the mechanisms through which IGF-1 exerts its anti-inflammatory and pro-angiogenic effects. These findings contribute to the understanding of IGF-1's role in wound healing and may have implications for the development of new wound treatment approaches.

Klotho supplementation attenuates blood pressure and albuminuria in murine model of IgA nephropathy

BACKGROUND

Klotho interacts with various membrane proteins, such as transforming growth factor-β (TGFβ) and insulin-like growth factor (IGF) receptors. The renal expression of klotho is diminished in chronic kidney disease.

METHOD

In this study, we assessed the effects of klotho supplementation on a murine model of IgA nephropathy. Twenty-four-week-old hyper serum IgA (HIGA) mice were subcutaneously injected daily with recombinant human klotho protein (20 μg/kg per day) or the vehicle. After 2 months, the mice were killed using an anesthesia overdose and their kidneys were harvested for analysis.

RESULTS

Supplementation of exogenous klotho protein reduced SBP, albuminuria, 8-epi-prostaglandin F2α excretion, glomerular filtration rate, renal angiotensin II concentration, and angiotensinogen expression in HIGA mice. Additionally, it enhanced renal expression of superoxide dismutase (SOD) and renal klotho itself. The findings using laser-manipulated microdissection demonstrated that klotho supplementation reduced the glomerular expression of TGFβ, fibronectin, and IGF, and increased the glomerular expression of connexin (Cx) 40.

CONCLUSION

These results indicate that klotho supplementation reduces blood pressure by suppressing the renin--angiotensin system in HIGA mice. Klotho inhibits IGF signaling to preserve glomerular Cx40 levels, ameliorating albuminuria in HIGA mice. Klotho protein supplementation attenuates mesangial expansion by inhibiting TGFβ signaling in HIGA mice.

Octreotide Delaying the Progression of Recurrent IgA Nephropathy After Kidney Transplantation

Supplemental Digital Content is available in the text.

IgA Nephropathy (IgAN) is a common cause of end-stage kidney disease worldwide. Unfortunately, the exact pathogenesis of IgAN remains uncertain without any targeted therapy. While kidney transplantation remains the gold standard treatment for those with end-stage kidney disease from IgAN, recurrence occurs frequently and may lead to early kidney transplant loss. Research has suggested that insulin-like growth factor-1 may play a role in mesangial cell proliferation in IgAN and Somatostatin may inhibit insulin-like growth factor-1. In this single case study, we report the use of octreotide, a somatostatin analogue, as a potential novel therapy for early recurrent IgAN post kidney transplant.

Rs1520220 and Rs2195239 Polymorphisms of IGF-1 Gene Associated with Histopathological Grades in IgA Nephropathy in Northwestern Chinese Han Population

BACKGROUND/AIMS

Insulin-like growth factor-1 (IGF-1) plays important roles in cellular proliferation, differentiation, and growth. Previous studies showed that single-nucleotide polymorphisms (SNPs) of IGF-1 are associated with various diseases. This case-control study aimed to examine the relationship between IGF-1 polymorphisms and IgA nephropathy (IgAN) risk in a Chinese Han population.

METHODS

We recruited 351 IgAN patients and 310 healthy controls from Northwestern China. Sequenom MassARRAY was utilized to examine the genotypes of two common IGF-1 SNPs (rs1520220 and rs2195239). Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated by the Chi square test to evaluate the associations between IGF-1 and IgAN.

RESULTS

Our study demonstrated that IGF-1 gene rs1520220 and rs2195239 polymorphisms did not confer susceptibility to IgAN. We found no correlation between gender, blood pressure, proteinuria, eGFR, and IgAN in both SNPs. However, the rs1520220 and rs2195239 variants were correlated with M1 and E1 in patients with IgAN (M0/M1: CC vs. CG+GG: OR = 1.62, P = 0.04; E0/E1: CC vs. CG+GG: OR = 1.95, P = 0.004; GG vs. GC+CC: OR = 1.90, P = 0.004, respectively).

CONCLUSION

These results indicate that IGF-1 gene polymorphisms play crucial roles in the histopathological progression of IgAN in the Chinese Han population.