Microsomal Prostaglandin E Synthase-1 Expression by Aortic Smooth Muscle Cells Attenuates the Differentiated Phenotype

The Emerging Therapeutic Role of Prostaglandin E2 Signaling in Pulmonary Hypertension

Mild-to-moderate pulmonary hypertension (PH) is a common complication of chronic obstructive pulmonary disease (COPD). It is characterized by narrowing and thickening of the pulmonary arteries, resulting in increased pulmonary vascular resistance (PVR) and ultimately leading to right ventricular dysfunction. Pulmonary vascular remodeling in COPD is the main reason for the increase of pulmonary artery pressure (PAP). The pathogenesis of PH in COPD is complex and multifactorial, involving chronic inflammation, hypoxia, and oxidative stress. To date, prostacyclin and its analogues are widely used to prevent PH progression in clinical. These drugs have potent anti-proliferative, anti-inflammatory, and stimulating endothelial regeneration properties, bringing therapeutic benefits to the slowing, stabilization, and even some reversal of vascular remodeling. As another well-known and extensively researched prostaglandins, prostaglandin E2 (PGE2) and its downstream signaling have been found to play an important role in various biological processes. Emerging evidence has revealed that PGE2 and its receptors (i.e., EP1-4) are involved in the regulation of pulmonary vascular homeostasis and remodeling. This review focuses on the research progress of the PGE2 signaling pathway in PH and discusses the possibility of treating PH based on the PGE2 signaling pathway.

Transforming growth factor-β1 and inducible nitric oxide synthase signaling were involved in effects of prostaglandin E2 on progression of lower limb varicose veins

OBJECTIVE

The vital pathogenesis of varicose veins includes remodeling of the extracellular matrix and decreased vascular tone. Prostaglandin E₂ (PGE₂), a small molecule substance and inflammatory medium that belongs to the arachidonic acid derivatives, has the capacity to influence the expression of metalloproteinase and the vascular tone of the venous wall. The purpose of the present study was to investigate the role of PGE₂ in the development of varicose veins in lower limbs.

METHODS

The collected venous specimens were analyzed using hematoxylin and eosin, Masson's trichrome, and immunohistochemical staining. Transforming growth factor (TGF)-β1, PGE₂, CD31, and α-smooth muscle actin antibody were used to detect the expression and distribution of these proteins. The effect of PGE₂ on the proliferation, migration, and tube formation capacity of human umbilical vein endothelial cells (HUVECs) was detected in vitro. The effect of TGF-β1 on the expression of PGE₂ and matrix metalloproteinases (MMPs) was assessed using Western blotting. Quantitative reverse transcription polymerase chain reaction was used to evaluate the effect of PGE₂ on the expression of nitric oxide synthase (NOS) and other genes.

RESULTS

The expression of PGE₂ and TGF-β1 in varicose veins was upregulated in the media tunica and intima tunica, and a strong positive correlation was found between PGE₂ and TGF-β1 expression in both varicose veins (95% confidence interval, 0.5207-0.9582; R = 0.848; P = .0005) and normal veins (95% confidence interval, 0.2530-0.8532; R = 0.643; P = .003). PGE₂ promoted the migration and tube formation ability of HUVECs. Moreover, PGE₂ also upregulated the expression of MMP-1 and TGF-β1 in HUVECs and increased the mRNA level of inducible NOS.

CONCLUSIONS

PGE₂ can affect the remodeling of the extracellular matrix and reduce the elasticity of the vascular walls by promoting the synthesis of TGF-β1 and MMP-1. PGE₂ can also reduce the tension of the great saphenous vein by promoting the expression of inducible NOS, thus aggravating the blood stasis.

Heme oxygenase-1 mitigates ferroptosis in renal proximal tubule cells

Ferroptosis is an iron-dependent form of regulated nonapoptotic cell death, which contributes to damage in models of acute kidney injury (AKI). Heme oxygenase-1 (HO-1) is a cytoprotective enzyme induced in response to cellular stress, and is protective against AKI because of its antiapoptotic and anti-inflammatory properties. However, the role of HO-1 in regulating ferroptosis is unclear. The purpose of this study was to elucidate the role of HO-1 in regulating ferroptotic cell death in renal proximal tubule cells (PTCs). Immortalized PTCs obtained from HO-1^+/+ and HO-1^-/- mice were treated with erastin or RSL3, ferroptosis inducers, in the presence or absence of antioxidants, an iron source, or an iron chelator. Cells were assessed for changes in morphology and metabolic activity as an indicator of cell viability. Treatment of HO-1^+/+ PTCs with erastin resulted in a time- and dose-dependent increase in HO-1 gene expression and protein levels compared with vehicle-treated controls. HO-1^-/- cells showed increased dose-dependent erastin- or RSL3-induced cell death in comparison to HO-1^+/+ PTCs. Iron supplementation with ferric ammonium citrate in erastin-treated cells decreased cell viability further in HO-1^-/- PTCs compared with HO-1^+/+ cells. Cotreatment with ferrostatin-1 (ferroptosis inhibitor), deferoxamine (iron chelator), or N-acetyl-l-cysteine (glutathione replenisher) significantly increased cell viability and attenuated erastin-induced ferroptosis in both HO-1^+/+ and HO-1^-/- PTCs. These results demonstrate an important antiferroptotic role of HO-1 in renal epithelial cells.