Mechanistic insights into the anti-restenotic effects of HSP27 and HO1 modulated by reconstituted HDL on neointimal hyperplasia.

High-density lipoprotein (HDL) therapy has demonstrated beneficial effects in acute stroke and acute myocardial infarction models by reducing infarct size. In this study, we investigated the inhibitory effects of reconstituted HDL (rHDL) on neointimal hyperplasia and elucidated its underlying mechanism using a balloon injury rat model. Our finding revealed a significant 37% reduction in the intima to media ratio in the arteries treated with 80 mg/kg rHDL compared to those subjected to injury alone (p < 0.05), indicating a specific inhibition of neointimal hyperplasia. In vivo analysis further supported the positive effects of rHDL by demonstrating a reduction in smooth muscle cell (SMC) proliferation and an increase in endothelial cell (EC) proliferation. Additionally, rHDL treatment led to decreased infiltration of leukocytes and downregulated the expression of matrix metallopeptidase 9 (MMP9) in the neointimal area. Notably, rHDL administration resulted in decreased expression of VCAM1 and HIF1α, alongside increased expression of heme oxygenase 1 (HO1) and heat shock protein 27 (HSP27). Overexpression of HSP27 and HO1 effectively inhibited SMC proliferation. Moreover, rHDL-mediated suppression of injury-induced HIF1α coincided with upregulation of HSP27. Interestingly, HSP27 and HO1 had varying effects on the expression of chemokine receptors and rHDL did not exert significant effect on chemokine receptor expression in THP1 cells. These findings underscore the distinct roles of HSP27 and HO1 as potential regulatory factors in the progression of restenosis. Collectively, our study demonstrates that rHDL exerts a potent anti-neointimal hyperplasia effect by reducing leukocytes infiltration and SMC proliferation while promoting EC proliferation.

An aptamer agonist of the insulin receptor acts as a positive or negative allosteric modulator, depending on its concentration.

Aptamers are widely used as binders that interact with targets with high affinity or as inhibitors of the function of target molecules. However, they have also been used to modulate target protein function, which they achieve by activating the target or stabilizing its conformation. Here, we report a unique aptamer modulator of the insulin receptor (IR), IR-A62. Alone, IR-A62 acts as a biased agonist that preferentially induces Y1150 monophosphorylation of IR. However, when administered alongside insulin, IR-A62 shows variable binding cooperativity depending on the ligand concentration. At low concentrations, IR-A62 acts as a positive allosteric modulator (PAM) agonist that enhances insulin binding, but at high concentrations, it acts as a negative allosteric modulator (NAM) agonist that competes with insulin for IR. Moreover, the concentration of insulin affects the binding of IR-A62 to IR. Finally, the subcutaneous administration of IR-A62 to diabetic mice reduces blood glucose levels with a longer-lasting effect than insulin administration. These findings imply that aptamers can elicit various responses from receptors beyond those of a simple agonist or inhibitor. We expect further studies of IR-A62 to help reveal the mechanism of IR activation and greatly expand the range of therapeutic applications of aptamers.

The herbal extract HMC05 inhibits neointima formation in balloon-injured rat carotid arteries: possible therapeutic implications of HMC05.

AIM OF THE STUDY: In a previous study, HMC05, a water extract from eight medicinal herbs was demonstrated to possess anti-inflammatory effects in murine macrophages and anti-atherosclerotic effects in apoE(-/-) mice. HSP27 expression was shown to be decreased in advanced atherosclerotic plaques of human carotid arteries. In the present study, the role of HMC05 in the prevention of restenosis and the possible mechanisms involved in the decrease of neointima formation were investigated using in vivo balloon injury rat model and in vitro biochemical assays. MATERIALS AND METHODS: A rat carotid artery balloon injury restenosis model was used. Different doses of HMC05 were administered to the rats by tube feeding, starting from four days before surgery and continuing twice per week for two weeks after carotid injury. Injured carotid arteries isolated from rats were embedded in paraffin block and tissue sections were stained with H&E to assess neointima formation. Mechanism by HMC05 that are involved in smooth muscle cell proliferation and migration was assessed by western blot assay, immunohistochemistry and confocal analysis. RESULTS: There was no significant difference in the medial area between the control and HMC05-treated groups. However, neointima formation was significantly inhibited in the HMC05-treated group, resulting in 47-fold lower intima to media ratios in rats treated with 25 mg/kg/day HMC05 as compared to the control. Surprisingly, monocytes infiltration in the neointima area was almost completely blocked by HMC05 administration. When rat vascular SMCs were treated with HMC05, the proliferation and migration of smooth muscle cells was dramatically inhibited in a dye uptake assay and in a scratch model in a culture dish, respectively. HMC05 dose-dependently inhibited PDGF-mediated MAPK and AKT activation. However, HMC05 did not affect PDGF-mediated HSP27 phosphorylation but it induced HSP27 overexpression and phosphorylation. In addition, medial SMCs in the arterial wall of rats treated with HMC05 showed a significant increase in HSP27 expression compared with that of the control rats. CONCLUSIONS: HMC05, a strong anti-inflammatory reagent, might use HSP27 as an effector molecule in SMCs to reduce neointimal hyperplasia by inhibiting PDGF-mediated MAPK and AKT activation. HMC05 could be a useful drug candidate for the prevention of restenosis after balloon injury of the arteries.

Evaluation of the Korean isolate-1 tachyzoite antigen for serodiagnosis of toxoplasmosis.

To evaluate the usefulness of the Korean Isolate-1 (KI-1) antigen for serodiagnosis of toxoplasmosis, antigen profiles of KI-1 tachyzoites were analyzed in comparison with RH tachyzoites by SDS-PAGE and immunoblotting. ELISA was performed on latex agglutination (LA)-positive and negative serum samples using KI-1 and RH antigens. Immunoblotting of the KI-1 antigen showed multiple antigen bands with molecular sizes of 22-105 kDa. Among them, 1 and 6 common bands were noted against a KI-1-infected and a RH-infected human serum, respectively, which represented differences in antigenic profiles between KI-1 and RH tachyzoites. However, all 9 LA-positive human sera were found positive by ELISA, and all 12 LA-negative sera were negative by ELISA; the correlation between the ELISA titers and LA titers was high (r = 0.749). Our results suggest that tachyzoites of KI-1 may be useful for serodiagnosis of human toxoplasmosis.