Seung Huh

Phage display selection of peptides that home to atherosclerotic plaques: IL-4 receptor as a candidate target in atherosclerosis

Imaging or drug delivery tools for atherosclerosis based on the plaque biology are still insufficient. Here, we attempted to identify peptides that selectively home to atherosclerotic plaques using phage display. A phage library containing random peptides was ex viv screened for binding to human atheroma tissues. After three to four rounds of selection, the DNA inserts of phage clones wer sequenced. A peptide sequence, CRKRLDRNC, was the most frequently occurring one. Intravenously injected phage displaying the CRKRLDRNC peptide was observed to home to atherosclerotic aortic tissues of low‐density lipoprotein receptor‐deficient (Ldlr−/–) mice at higher levels than to normal aortic tissues of wild‐type mice. Moreover, a fluorescein‐ or radioisotope‐conjugated synthetic CRKRLDRNC peptide, but not a control peptide, homed in vivo to atherosclerotic plaques in Ldlr−/– mice, while homing of the peptide to other organs such as brain was minimal. The homing peptide co‐localized with endothelial cells, macrophages and smooth muscle cells a mouse and human atherosclerotic plaques. Homology search revealed that the CRKRLDRNC peptide shares a motif of interleukin‐receptor (IL‐4) that is critical for binding to its receptor. The peptide indeed co‐localized with IL‐4 receptor (IL‐4R) at atherosclerotic plaques. Moreover, the peptide bound to cultured cells expressing IL‐4R on the cell surface and the binding was inhibited by the knock‐down of IL‐4R. These results show that the CRKRLDRNC peptide homes to atherosclerotic plaques through binding to IL‐4R as its target and may be a useful tool for selective drug delivery and molecular imaging of atherosclerosis.

Activation of NAD(P)H:Quinone Oxidoreductase 1 Prevents Arterial Restenosis by Suppressing Vascular Smooth Muscle Cell Proliferation

Abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) are important pathogenic mechanisms in atherosclerosis and restenosis after vascular injury. In this study, we investigated the effects of β-lapachone (βL) (3,4-Dihydro-2,2-dimethyl-2H-naphtho[1,2-b]pyran-5,6-dione), which is a potent antitumor agent that stimulates NAD(P)H:quinone oxidoreductase (NQO)1 activity, on neointimal formation in animals given vascular injury and on the proliferation of VSMCs cultured in vitro. βL significantly reduced the neointimal formation induced by balloon injury. βL also dose-dependently inhibited the FCS- or platelet-derived growth factor–induced proliferation of VSMCs by inhibiting G1/S phase transition. βL increased the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase 1 in rat and human VSMCs. Chemical inhibitors of AMPK or dominant-negative AMPK blocked the βL-induced suppression of cell proliferation and the G1 cell cycle arrest, in vitro and in vivo. The activation of AMPK in VSMCs by βL is mediated by LKB1 in the presence of NQO1. Taken together, these results show that βL inhibits VSMCs proliferation via the NQO1 and LKB1-dependent activation of AMPK. These observations provide the molecular basis that pharmacological stimulation of NQO1 activity is a new therapy for the treatment of vascular restenosis and/or atherosclerosis which are caused by proliferation of VSMCs.

Clinical and radiologic course of symptomatic spontaneous isolated dissection of the superior mesenteric artery treated with conservative management

OBJECTIVE To determine the clinical and radiological outcomes of patients with symptomatic spontaneous isolated dissection of the superior mesenteric artery (SIDSMA) who were treated with conservative management. METHODS This retrospective study included 27 consecutive patients who were diagnosed with symptomatic SIDSMA and managed conservatively from April 2007 to April 2013. Twenty-six patients were treated using anticoagulation therapy, and one patient with chronic liver disease underwent observation only. For evaluation, patients were divided into two groups, those with a patent false lumen with both entry and re-entry (group I), and those with partial or complete thrombosis of the false lumen (group II). In general, the patients underwent follow-up computed tomography angiography (CTA) 1 week, 1 month, and 6 months after admission. Thereafter, they underwent annual CTAs. RESULTS There were five group I and 22 group II patients. During hospitalization, none of the patients needed additional endovascular or surgical intervention, and after conservative management, every patient was asymptomatic upon discharge. The mean duration of clinical follow-up was 27.3 months. There was no recurrent abdominal pain associated with SIDSMA, and no invasive procedures due to SIDSMA were needed. During a mean of 17.1 months of CTA follow-up in group I patients, serial CTAs found sustained patent false lumen and no angiographic changes in all patients. Among 22 group II patients, despite anticoagulation and symptomatic relief, CTA 1 week after admission revealed increased stenosis of the true lumen in 84.2% (16/19) of patients including six cases of progressive SMA occlusion. Five patients, including the three patients initially presenting with SMA occlusion, had no interval changes, and only one patient had improved compression of the true lumen. During a mean of 18.0 months of CTA follow-up in group II patients, serial CTAs revealed improvement in the occlusion or stenosis of the true lumen in 89% (16/18) of patients and progressive resolution of false lumen thrombosis in all patients. Aneurysmal dilatation greater than 2 cm was not detected in either group of patients during follow-up. CONCLUSIONS During the acute stage of SIDSMA, we found a discrepancy between the clinical and angiographic findings. The therapeutic regimen should be based on clinical symptoms, and conservative management is feasible in most cases. SMA stenosis could not be an indication for invasive treatment, because stenosis of the true lumen has been seen to improve after the acute stage of dissection.

Risk Factors for Recurrent Urinary Tract Infection in Kidney Transplant Recipients

BACKGROUND Urinary tract infections (UTIs) are the most common infectious complication in kidney transplant recipients (KTRs). The aim of this study to investigate the risk factors for and causative organisms of UTI as well as to evaluate the impact these diseases on allograft function in KTRs. METHODS We analyzed patients who underwent kidney transplantation (KT) between January 2000 and December 2010. Among a total of 344 KTRs, 50 (14.5%) patients experienced 106 UTI episodes during a mean follow-up of 35.9 ± 26.0 months. Twenty three patients experiencing recurrent UTI were compared with 27 nonrecurrent UTI patients and with 50 non-UTI patients matched for age, gender, and transplantation date. RESULTS The number of patients with renal calculi, diabetes, or prior dialysis was significantly greater among the UTI group compared with control subjects. In addition, the number of patients with renal calculi was significantly higher among the recurrent compared with the nonrecurrent cohort (43.5 vs 7.4%; P = .003). The most common causative organism was Escherichia coli (64.1%), followed by Enterococcus species (20.5%). Higher rates of antibiotic resistance, especially Extended Spectrum Beta-Lactamasc (ESBL) production, were observed among the recurrent compared with the nonrecurrent group (53.1 vs 0%; P = .013). The rate of decline of estimated glomerular filtration rate was significantly faster in the UTI than the non-UTI group, whereas it did not differ between the recurrent and nonrecurrent group. CONCLUSIONS Adequate treatment of an initial UTI to prevent as recurrent infection and prolong graft longevity is especially reasonable for KTRs with renal calculi or in cases of antibiotic-resistant microorganisms.

Treatment outcome in patients with acute superior mesenteric artery embolism.

PURPOSE The goals of this study were to investigate the treatment outcomes of acute mesenteric ischemia caused by superior mesenteric artery (SMA) embolism and identify the posttreatment prognostic factors. METHODS The clinical data of 32 episodes of acute SMA embolism in 30 patients, including 2 recurrent cases, between April 2003 and March 2011 were retrospectively reviewed. RESULTS Median patient age was 74 years (range, 39-89 years), and 50% were male. Conservative treatment, including bowel rest, nasogastric drainage, intravenous fluid therapy, parenteral nutritional support, and anticoagulation therapy, was undertaken in 5 patients with no clinical evidence of bowel gangrene, including 1 with recurrent ischemia. No deaths occurred among patients treated conservatively. A total of 27 patients were treated with open surgical repair (25 embolectomies and 2 bowel resections alone). Among 25 patients treated with embolectomy, 14 required bowel resection. Most bowel resections (94%, 15/16) were limited, with the remaining length of small bowel greater than 150 cm, which could not cause short bowel syndrome. In-hospital mortality of surgery was 30%. No variables were associated with mortality after surgical intervention, including, age, gender, presence of bowel gangrene, and symptom duration. The overall 1-, 3-, and 5-year survival rates after initial successful treatment were 96%, 73%, and 44%, respectively, regardless of treatment type. CONCLUSIONS Prompt diagnosis and treatment before extensive irreversible gangrene is the mainstay in the treatment of SMA embolism. Limited bowel gangrene was not associated with mortality.

Venous Thromboembolism in Korean Patients Undergoing Major Orthopedic Surgery: A Prospective Observational Study using Computed Tomographic (CT) Pulmonary Angiography and Indirect CT Venography

In patients undergoing major orthopedic surgery, data of deep venous thrombosis (DVT) and pulmonary embolism (PE) are lacking as studied by computed tomographic (CT) pulmonary angiography and indirect CT venography (CTPA-CTV). A prospective observational study was performed for 363 Korean patients undergoing major orthopedic surgery to determine the incidence of venous thromboembolism (VTE), especially proximal DVT and PE. The incidence of VTE was 16.3% (n=59). Of them, 8 patients (2.2%) were symptomatic. The rate of VTE was the highest in patients who underwent total knee replacement (40.4%), followed by hip fracture surgery (16.4%), and total hip replacement (8.7%; P<0.001). The incidence of PE was 6.6% (n=24). Of them, 4 patients (1.1%) were symptomatic. Forty-one patients (11.3%) were in the proximal DVT or PE group. Based on multivariate analysis, total knee replacement and age ≥65 yr were significant risk factors for proximal DVT or PE in patients undergoing major orthopedic surgery (odds ratio [OR], 2.4; 95% confidence interval [CI], 1.1-5.1; P=0.025; and OR, 2.1; 95% CI, 1.0-4.4; P=0.046, respectively). Taken together, the overall incidence of PE was 6.6% and rate of symptomatic PE rate was 1.1%. Knee joint replacement and age ≥65 yr were significant risk factors for proximal DVT or PE.

Successful withdrawal of antiviral treatment in kidney transplant recipients with chronic hepatitis B viral infection.

The optimal duration of antiviral therapy for kidney transplant recipients (KTR) with chronic hepatitis B virus (HBV) infection remains unclear. We reported the long‐term outcomes after withdrawal of antiviral agent in KTR with chronic HBV infection.

Positive Cross-Talk Between Hypoxia Inducible Factor-1α and Liver X Receptor α Induces Formation of Triglyceride-Loaded Foam Cells

Objective—Atherosclerosis is a chronic and progressive inflammatory disease of the arteries that is characterized by subendothelial accumulation of lipid-rich macrophages, called foam cells. We sought to identify the molecular details of cross-talk between liver X receptor &agr; (LXR&agr;) and hypoxia-inducible factor 1&agr; (HIF-1&agr;) for the formation of triglyceride-rich foam cells under hypoxic conditions. Methods and Results—We first observed that expression of LXR&agr; and its target lipogenic genes was time-dependently induced in human primary macrophages and RAW 264.7 cells under hypoxia. Similarly, TO901317, an activator of LXR&agr;, enhanced the expression level and the transcriptional activity of HIF-1&agr;. Second, we demonstrated that LXR&agr; increased HIF-1&agr; protein stability through a physical interaction between the ligand binding domain of LXR&agr; and the oxygen-dependent degradation domain of HIF-1&agr;. Third, we found that the activation of HIF-1&agr; or LXR&agr; synergistically induced triglyceride accumulation in macrophages. Finally, we showed that LXR&agr; and HIF-1&agr; were codistributed in the macrophages of atherosclerotic lesions of patients. Conclusion—These results suggest that the positive feed-forward regulation of transcriptional activity and protein stability of LXR&agr; and HIF-1&agr; has an important impact in foam cell formation.

Successful treatment of recurrent focal segmental glomerulosclerosis with a low dose rituximab in a kidney transplant recipient

Abstract Recurrence of focal segmental glomerulosclerosis (FSGS) is a major therapeutic challenge in kidney transplantation (KT). Although intensive plasmapheresis and high-dose rituximab have been introduced to treat recurrent FSGS, the most effective dosage and regimen of rituximab have not been determined. Herein we reported the first case of successful treatment of recurrent FSGS with a low-dose rituximab. The patient showed marked proteinuria (3.5 g/d) and oliguria 2 d after KT. Two courses of plasmapheresis and immunoglobulin were applied to the patient, however, nephrotic range proteinuria persisted and creatinine level increased to 3.56 mg/dL. Five months post-transplant, the patient received injection with only one dose of rituximab 100 mg, without further plasmapheresis, which resulted in immediate reduction of serum creatinine and full remission of proteinuria during the following 18 months. This case suggested that recurrent FSGS, which frequently relapses after plasmapheresis, could be treated successfully with a low-dose rituximab even without plasmapheresis.

Pyruvate Dehydrogenase Kinase 4 Promotes Vascular Calcification via SMAD1/5/8 Phosphorylation.

Vascular calcification, a pathologic response to defective calcium and phosphate homeostasis, is strongly associated with cardiovascular mortality and morbidity. In this study, we have observed that pyruvate dehydrogenase kinase 4 (PDK4) is upregulated and pyruvate dehydrogenase complex phosphorylation is increased in calcifying vascular smooth muscle cells (VSMCs) and in calcified vessels of patients with atherosclerosis, suggesting that PDK4 plays an important role in vascular calcification. Both genetic and pharmacological inhibition of PDK4 ameliorated the calcification in phosphate-treated VSMCs and aortic rings and in vitamin D3-treated mice. PDK4 augmented the osteogenic differentiation of VSMCs by phosphorylating SMAD1/5/8 via direct interaction, which enhances BMP2 signaling. Furthermore, increased expression of PDK4 in phosphate-treated VSMCs induced mitochondrial dysfunction followed by apoptosis. Taken together, our results show that upregulation of PDK4 promotes vascular calcification by increasing osteogenic markers with no adverse effect on bone formation, demonstrating that PDK4 is a therapeutic target for vascular calcification.