Influence of agglomeration and specific lung lining lipid/protein interaction on short-term inhalation toxicity.

Lung lining fluid is the first biological barrier nanoparticles (NPs) encounter during inhalation. As previous inhalation studies revealed considerable differences between surface functionalized NPs with respect to deposition and toxicity, our aim was to investigate the influence of lipid and/or protein binding on these processes. Thus, we analyzed a set of surface functionalized NPs including different SiO2 and ZrO2 in pure phospholipids, CuroSurf(TM) and purified native porcine pulmonary surfactant (nS). Lipid binding was surprisingly low for pure phospholipids and only few NPs attracted a minimal lipid corona. Additional presence of hydrophobic surfactant protein (SP) B in CuroSurf(TM) promoted lipid binding to NPs functionalized with Amino or PEG residues. The presence of the hydrophilic SP A in nS facilitated lipid binding to all NPs. In line with this the degree of lipid and protein affinities for different surface functionalized SiO2 NPs in nS followed the same order (SiO2 Phosphate ∼ unmodified SiO2 < SiO2 PEG < SiO2 Amino NPs). Agglomeration and biomolecule interaction of NPs in nS was mainly influenced by surface charge and hydrophobicity. Toxicological differences as observed in short-term inhalation studies (STIS) were mainly influenced by the core composition and/or surface reactivity of NPs. However, agglomeration in lipid media and lipid/protein affinity appeared to play a modulatory role on short-term inhalation toxicity. For instance, lipophilic NPs like ZrO2, which are interacting with nS to a higher extent, exhibited a far higher lung burden than their hydrophilic counterparts, which deserves further attention to predict or model effects of respirable NPs.

Intramural delivery of Sirolimus prevents vascular remodeling following balloon injury.

OBJECTIVE: Several studies have demonstrated that Sirolimus-eluting stents reduce restenosis in patients with coronary artery disease. Here, we tested whether direct delivery of Sirolimus into the vessel wall during balloon angioplasty can modify vascular remodeling over several weeks. METHODS AND RESULTS: During angioplasty of the rabbit iliac artery we administered an intramural infusion of Sirolimus or its vehicle directly through a balloon catheter into the vessel wall. After 3 weeks neointimal formation was decreased (0.71+/-0.1 vs. 1.4+/-0.12 intima/media ratio), and this process was attributed to the inhibitory properties of Sirolimus on ECM deposition and smooth muscle cell proliferation. Sirolimus also significantly reduced the deposition of elastin, collagen III and fibronectin within the vascular wall. In parallel, proteomic profiles of arterial wall segments were obtained and 485 protein spots were consistently matched between non-dilated and dilated vessels. Differential expression of 12 proteins were observed between the groups and direct sequencing of digested peptides was performed. Local delivery of sirolimus during angioplasty attenuated the expression of structural proteins that included lamin A, vimentin, alpha-1-antitrypsin, and alpha-actin. CONCLUSIONS: Local administration of Sirolimus during angioplasty prevents smooth muscle cell proliferation associated with vascular remodeling as well as the expression of extracellular matrix and structural proteins. Therefore, local injection of Sirolimus during balloon inflation may be an alternative therapeutic approach for preventing restenosis in small stenotic vessels (i.e., <2.5 mm).

Proteome analysis of myocardial tissue following ischemia and reperfusion--effects of complement inhibition.

Myocardial ischemia-reperfusion injury can be related to complement activation with generation of chemotactic mediators, release of cytokines, leukocyte accumulation, and subsequent severe tissue injury. In this regard, activation of transcription factors (i.e., NFkappaB) and de novo protein synthesis or inflammatory protein degradation seems to play an important role. In the present study, we analyzed the cardiac protein expression following myocardial ischemia (60 min) and reperfusion (180 min) in a rabbit model utilizing two-dimensional electrophoresis and nanoHPLC/ESI-MS/MS for biochemical protein identification. To achieve cardioprotective effects, we used a novel highly selective small molecule C1s inhibitor administered 5 min prior to reperfusion. The reduction of myocardial injury was observed as diminished plasma creatine kinase activity in C1s-INH-248-treated animals (65.2+/-3 vs. 38.5+/-3 U/g protein after 3 h of reperfusion, P<0.05). With proteome analysis we were able to detect 509+/-21 protein spots on the gels of the 3 groups. A pattern of 480 spots with identical positions was found on every gel of myocardial tissue of sham animals, vehicle and C1s-INH-248-treated animals. We analyzed 11 spots, which were identified by mass spectrometry: Superoxide dismutase, alpha-crystallin-chain-B, mitochondrial stress protein, Mn SOD, ATP synthase A chain heart isoform, creatine kinase, and troponin T. All of these proteins were significantly decreased in the vehicle group when we compared to sham-treated animals. Treatment with C1s-INH-248 preserved levels of these proteins. Thus, blocking the classical complement pathway with a highly specific and potent synthetic inhibitor of the activated C1 complex archives cardio-protection by altering and preserving different anti-inflammatory and cytoprotective cascades.

Two-dimensional analysis of myocardial protein expression following myocardial ischemia and reperfusion in rabbits.

Myocardial ischemia and reperfusion injury (MI/R) can be related to leukocyte activation with subsequent release of cytokines and oxygen derived free radicals. Activation of the complement system has been implicated in the pathogenesis of myocardial ischemia and reperfusion injury. Inflammatory injury will subsequently result in cellular activation and protein synthesis. In the present study we analyzed the myocardial protein expression and its pattern following myocardial ischemia and reperfusion, with and without complement inhibition with the synthetic serine protease inhibitor Futhan/nafamstat mesilate (FUT-175) known to inhibit classical and alternative complement pathway in a rabbit model of myocardial ischemia and reperfusion (60 min I+180 min R). FUT-175 significantly reduced myocardial necrosis, i.e. creatine kinase release which were analyzed for the three groups (p<0.05). Similarly, histological analysis demonstrated preservation of myocardial tissue injury and reduced leukocyte accumulation following FUT-175 treatment. Further, the myocardial protein expression was analyzed by two-dimensional gel electrophoresis following MI/R in the different groups. The protein patterns were evaluated by means of MELANIE III, a computer assisted gel analysis system. The biochemical identification of the proteins of interest was, achieved using nanohigh-performance liquid chromatography/electrospray ionization-tandem mass spectrometry. On average, 509 +/- 25 protein spots were found on the gels. A pattern of 480 spots with identical positions was found on every gel of five animals of each group. We analyzed ten spots which were significantly altered (i.e., in eight spots we observed decreased protein expression and in two spots we observed increased expression, vehicle vs. sham), by using mass spectrometry. Superoxide dismutase precursor and alphaB-crystallin were identified. We compared sham group vs. vehicle group and vehicle group vs. FUT-175 treated animals. Expression of the two identified proteins decreased by half the amount in the vehicle group when compared to sham treated animals. Treatment with FUT-175 preserved significantly superoxide dismutase precursor and alphaB-crystallin protein expression when compared to vehicle animals. The results present marked differences in myocardial protein expression after ischemia and reperfusion and following treatment with the complement inhibitor FUT-175. Our results illustrate the application of proteomics to discover possible new therapeutic targets or to detect unexpected effects of pharmacological inhibitors.