Mark Hsu

Statin treatment increases formation of carbon monoxide and bilirubin in mice: a novel mechanism of in vivo antioxidant protection

Heme oxygenase (HO) has a central role in cellular antioxidant defences and vascular protection, and it may mediate pleiotropic actions of drugs used in cardiovascular therapy. We investigated whether long-term use of statins upregulates HO activity and increases carbon monoxide (CO) and bilirubin levels in vivo. Adult FvB mice were given atorvastatin or rosuvastatin (5 mg/kg) daily by i.p. injections for 1, 2, or 3 weeks. HO activity, tissue CO, bilirubin, and antioxidant levels, total plasma bilirubin, and carboxyhemoglobin (COHb) were measured. Fold changes in heart HO activity significantly increased after 1, 2, and 3 weeks of atorvastatin (1.24 +/- 0.06 (p < or = 0.05); 1.29 +/- 0.26 (p < or = 0.03); 1.33 +/- 0.08 (p < 0.01), respectively) and 2 and 3 weeks of rosuvastatin (1.23 +/- 0.20 (p < or = 0.03); 1.63 +/- 0.42 (p < 0.01), respectively). Heart tissue CO and COHb levels also increased after 3 weeks with atorvastatin (1.30 +/- 0.24 (p < or = 0.05); 1.92 +/- 0.17 (p < or = 0.001), respectively) and rosuvastatin (1.47 +/- 0.13 (p < or = 0.004); 1.63 +/- 0.12 (p < or = 0.001), respectively). Significant increases in heart antioxidant levels were observed after statin treatment and corroborated by heart bilirubin content elevations. Antioxidant level increases were abolished by treatment with an HO inhibitor. These findings suggest that the induction of HO and the production of its products, CO and bilirubin, may be a mechanism by which statins exert antioxidant actions and confer cardioprotection in vivo.

Transcriptional profiling and network analysis of the murine angiotensin II-induced abdominal aortic aneurysm

We sought to characterize temporal gene expression changes in the murine angiotensin II (ANG II)-ApoE-/- model of abdominal aortic aneurysm (AAA). Aortic ultrasound measurements were obtained over the 28-day time-course. Harvested suprarenal aortic segments were evaluated with whole genome expression profiling at 7, 14, and 28 days using the Agilent Whole Mouse Genome microarray platform and Statistical Analysis of Microarrays at a false discovery rate of <1%. A group of angiotensin-treated mice experienced contained rupture (CR) within 7 days and were analyzed separately. Progressive aortic dilatation occurred throughout the treatment period. However, the numerous early expression differences between ANG II-treated and control were not sustained over time. Ontologic analysis revealed widespread upregulation of inflammatory, immune, and matrix remodeling genes with ANG II treatment, among other pathways such as apoptosis, cell cycling, angiogenesis, and p53 signaling. CR aneurysms displayed significant decreases in TGF-β/BMP-pathway signaling, MAPK signaling, and ErbB signaling genes vs. non-CR/ANG II-treated samples. We also performed literature-based network analysis, extracting numerous highly interconnected genes associated with aneurysm development such as Spp1, Myd88, Adam17 and Lox. 1) ANG II treatment induces extensive early differential expression changes involving abundant signaling pathways in the suprarenal abdominal aorta, particularly wide-ranging increases in inflammatory genes with aneurysm development. 2) These gene expression changes appear to dissipate with time despite continued growth, suggesting that early changes in gene expression influence disease progression in this AAA model, and that the aortic tissue adapts to prolonged ANG II infusion. 3) Network analysis identified nexus genes that may constitute aneurysm biomarkers or therapeutic targets.

Intraoperative optical imaging and tissue interrogation during urologic surgery.

Purpose of review To review optical imaging technologies in urologic surgery aimed to facilitate intraoperative imaging and tissue interrogation. Recent findings Emerging new optical imaging technologies can be integrated in the operating room environment during minimally invasive and open surgery. These technologies include macroscopic fluorescence imaging that provides contrast enhancement between normal and diseased tissue and microscopic imaging that provides tissue characterization. Summary Optical imaging technologies that have reached the clinical arena in urologic surgery were reviewed, including photodynamic diagnosis, near infrared fluorescence imaging, optical coherence tomography, and confocal laser endomicroscopy.

Length of site-specific positive surgical margins as a risk factor for biochemical recurrence following radical prostatectomy.

Objectives:  Positive surgical margins (PSM) have been associated with biochemical recurrence (BCR) after radical prostatectomy, but the significance of PSM length and location are debated. We assessed the impact of PSM lengths at specific locations for BCR in an open radical prostatectomy series.

Heme Oxygenase-1 Expression Affects Murine Abdominal Aortic Aneurysm Progression

Heme oxygenase-1 (HO-1), the rate-limiting enzyme in heme degradation, is a cytoprotective enzyme upregulated in the vasculature by increased flow and inflammatory stimuli. Human genetic data suggest that a diminished HO-1 expression may predispose one to abdominal aortic aneurysm (AAA) development. In addition, heme is known to strongly induce HO-1 expression. Utilizing the porcine pancreatic elastase (PPE) model of AAA induction in HO-1 heterozygous (HO-1+/-, HO-1 Het) mice, we found that a deficiency in HO-1 leads to augmented AAA development. Peritoneal macrophages from HO-1+/- mice showed increased gene expression of pro-inflammatory cytokines, including MCP-1, TNF-alpha, IL-1-beta, and IL-6, but decreased expression of anti-inflammatory cytokines IL-10 and TGF-beta. Furthermore, treatment with heme returned AAA progression in HO-1 Het mice to a wild-type profile. Using a second murine AAA model (Ang II-ApoE-/-), we showed that low doses of the HMG-CoA reductase inhibitor rosuvastatin can induce HO-1 expression in aortic tissue and suppress AAA progression in the absence of lipid lowering. Our results support those studies that suggest that pleiotropic statin effects might be beneficial in AAA, possibly through the upregulation of HO-1. Specific targeted therapies designed to induce HO-1 could become an adjunctive therapeutic strategy for the prevention of AAA disease.

Endoscopic Fluorescence Imaging of Bladder Cancer: Photodynamic Diagnosis and Confocal Laser Endomicroscopy

Photodynamic diagnosis and confocal laser endomicroscopy hold promise in enhancing the urologist’s approach to examining the lower urinary tract. While both technologies have potential in diagnosis and treatment, they also have inherent limitations that one must be aware of and also have costs in terms of instrumentation, contrast agents, and additional operative time. Being investigated for their potential in this strategy of readily identifying lesions with real-time histologic confirmation. Future studies will focus on the diagnostic accuracy of CLE for bladder cancer, particularly the challenging flat, erythematous lesions. In addition, CLE may be expanded to other urologic applications, including the upper urinary tract and during laparoscopic and robotic-assisted surgery.

Molecular Imaging in Urology

Imaging plays an integral role in urology by providing anatomical detail and diagnostic insight of urologic diseases. Cross-sectional imaging technologies including computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US) are used primarily for initial diagnosis, surgical planning, and disease surveillance. In the operating room setting, optical imaging based on white light has provided the illumination for endourologic procedures of the upper and lower urinary tracts, as well as complex abdominal and pelvic surgeries increasingly performed through the laparoscopic/robotic approach. Nevertheless, current imaging technologies still carry limitations such as inadequate sensitivity in early detection of metastases (CT and MRI) and suboptimal diagnostic accuracy (e.g., white-light cystoscopy). Molecular imaging offers the possibility of improved early detection, intraoperative surgical guidance with molecular specificity, and therapeutic monitoring. This review focuses on this exciting emerging field within urology.

CHRONIC ADMINISTRATION OF STATINS ON IN VIVO HEME OXYGENASE EXPRESSION: A NOVEL MECHANISM OF ANTIOXIDANT PROTECTION.: 72

Heme oxygenase (HO) is the rate-limiting enzyme in degrading heme to form bilirubin and thus serves as an ideal therapeutic target for preventing neonatal jaundice. Understanding the regulatory pathways of HO is crucial for developing strategies for this disorder. We have previously shown that statins, inhibitors of 3-hydroxyl-3-methylglutaryl coenzyme A (HMG-CoA) reductase, selectively induce the HO-1 isozyme in vivo following a large single oral dose. The objective in this study was to investigate the effects of chronic administration of statins on in vivo induction of HO-1 expression. Adult mice were given atorvastatin or rosuvastatin (5 mg/kg body weight) or vehicle (control) by daily intraperitoneal injections for 1, 2, or 3 weeks. At each time point, mice were sacrificed. HO activity and tissue carbon monoxide (CO) levels in the liver, lung, brain, and heart were measured and then expressed as fold change from control levels. Total serum bilirubin (TSB) and carboxyhemoglobin (COHb) levels were measured after 3 weeks of statin treatment. Heart HO activity significantly increased after 2 and 3 weeks of treatment with atorvastatin (1.24 ± 0.27 [n = 7, p = .04] and 1.27 ± 0.07 [n = 4, p = .0009], respectively) and rosuvastatin (1.20 ± 0.13 [n = 5, p = .02] and 1.48 ± 0.27 [n = 5, p = .01], respectively). After 3 weeks of treatment, similar increases in heart tissue CO and COHb levels with atorvastatin (1.30 ± 0.24 [n = 5, p = .023] and 1.92 ± 0.17 [n = 5, p = .001], respectively) and rosuvastatin (1.47 ± 0.13 [n = 3, p = .01] and 1.63 ± 0.12 [n = 5, p = .001], respectively) were also found. Significant increases in antioxidant capacity in the heart in both atorvastatin- (n = 4) and rosuvastatin- (n = 5) treaqted mice were also observed and were paralleled by elevations in TSB of 1.49 ± 0.15-fold (p = .001) and 1.14 ± 0.14-fold (p = .02) from baseline levels, respectively. We conclude that the induction of HO activity by chronic treatment with atorvastatin and rosuvastatin is primarily in the heart. Subsequent production of CO and bilirubin, bioactive metabolic products of HO-1, is the major mechanism by which statins exert their antioxidant actions on the cardiovascular system and confer cardiac cytoprotection. This work was study was supported in part by National Institutes of Health grant #HD58013 and AstraZeneca grant #1RUSROSU0190.

239 STATINS AS TISSUE-SPECIFIC INDUCERS OF IN VIVO HEME OXYGENASE EXPRESSION.:

Heme oxygenase (HO) is the rate-limiting enzyme in degrading heme to form bilirubin, and thus serves as an ideal therapeutic target for preventing neonatal jaundice. Understanding the regulatory pathways of HO is crucial for developing strategies for this disorder. Statins, inhibitors of 3-hydroxyl-3-methylglutaryl coenzyme A (HMG-CoA) reductase, have been reported to induce HO-1. Our objective was to characterize the effects of statins with different structures and lipophilicities on in vivo induction of HO-1 expression. Adult FVB mice (6-8 weeks old) were orally administered 100 mg/kg body weight of simvastatin, lovastatin, atorvastatin, or rosuvastatin. 24 hours after treatment, mice were sacrificed, and tissues were harvested, sonicated, and then analyzed for HO activity [carbon monoxide (CO) formation] by gas chromatography and HO proteins by Western blot. HO activity was calculated as pmol CO produced/hour/mg fresh weight. HO protein levels were measured by densitometry. All values were then expressed as mean ± SD percent of control levels (*p ≤ .03) as follows: Simvastatin did not affect brain HO activity. Liver HO activity was not induced by atorvastatin or rosuvastatin. Lovastatin increased HO activity in all tissues. Interestingly, all statins significantly increased HO activity in the heart and lung. When HO protein levels were measured in atorvastatin-treated mice, corresponding significant increases in HO-1 protein in the heart (132 ± 39%; n = 6) and lung (136 ± 13%; n = 4) were found, whereas no changes in HO-2 protein levels were observed in either tissue. We conclude that the induction of HO activity is statin- as well as tissue-specific. However, further studies are needed to elucidate the exact mechanism by which statins differentially induce HO expression in various organs. This work was study was supported in part by National Institutes of Health grant #HD58013.