Elevated lipoprotein(a) increases risk of subsequent major adverse cardiovascular events (MACE) and coronary revascularisation in incident ASCVD patients: A cohort study from the UK Biobank.

BACKGROUND AND AIMS: Elevated lipoprotein(a) [Lp(a)] is a genetic driver for atherosclerotic cardiovascular disease (ASCVD). We aimed to provide novel insights into the associated risk of elevated versus normal Lp(a) levels on major adverse cardiovascular events (MACE) in an incident ASCVD cohort. METHODS: This was an observational cohort study of incident ASCVD patients. MACE counts and incidence rates (IRs) per 100-person-years were reported for patients with normal (<65 nmol/L) and elevated (>150 nmol/L) Lp(a) within the first year after incident ASCVD diagnosis and overall follow-up. Cox proportional hazard models quantified the risk of MACE associated with a 100 nmol/L increase in Lp(a). RESULTS: The study cohort included 32,537 incident ASCVD patients; 5204 with elevated and 22,257 with normal Lp(a). Of those with elevated Lp(a), 41.2% had a subsequent MACE, versus 35.61% with normal Lp(a). Within the first year of follow-up, the IRs of composite MACE and coronary revascularisation were significantly higher (p < 0.001) in patients with elevated versus normal Lp(a) (IR difference 6.79 and 4.66). This trend was also observed in the overall follow-up (median 4.7 years). Using time to first subsequent MACE, a 100 nmol/L increase in Lp(a) was associated with an 8.0% increased risk of composite MACE, and 18.6% increased risk of coronary revascularisation during the overall follow-up period. CONCLUSIONS: The association of elevated Lp(a) with increased risk of subsequent MACE and coronary revascularisation highlights a population who may benefit from earlier and more targeted intervention for cardiovascular risk including Lp(a), particularly within the first year after ASCVD diagnosis. Proactive Lp(a) testing as part of routine clinical practice can help identify and better manage these higher-risk individuals.

Smac-Derived Aza-Peptide As an Aminopeptidase-Resistant XIAP BIR3 Antagonist.

The peptidic nature of anti-IAPs N-terminus Smac-derived peptides precludes their utilization as potential therapeutic anticancer agents. Recent advances in the development of novel Smacderived peptidomimetics and non-peptidic molecules with improved anti-IAPs activity and resistance to proteolytic cleavage have been reported and led to a number of candidates that are currently in clinical trials including LCL-161, SM-406/AT-406, GDC-0512/GDC-0917, and birinapant. As an attempt to improve the proteolytic stability of Smac peptides, we developed the Aza-peptide AzaAla- Val-Pro-Phe-Tyr-NH2 (2). Unlike unmodified peptide Ala-Val-Pro-Phe-Tyr-NH2 (1), analogue (2) exhibited resistance towards proteolytic cleavage by two aminopeptidases; LAP and DPP-IV, while retaining its IAP inhibitory activity. This was due to the altered planar geometry of the P1 residue side chain. Our findings showed that using aza-isosteres of bioactive peptide sequences imbue the residue with imperviousness to proteolysis; underscoring a potential approach for developing a new generation of Smac-derived Aza-peptidomimetics.

Solid phase synthesis of Smac/DIABLO-derived peptides using a 'Safety-Catch' resin: identification of potent XIAP BIR3 antagonists.

The N-terminal sequence of the Smac/DIABLO protein is known to be involved in binding to the BIR3 domain of the anti-apoptotic proteins IAPs, antagonizing their action. Short peptides and peptide mimetics based on the first 4-residues of Smac/DIABLO have been demonstrated to re-sensitize resistant cancer cells, over-expressing IAPs, to apoptosis. Based on the well-defined structural basis for this interaction, a small focused library of C-terminal capped Smac/DIABLO-derived peptides was designed in silico using docking to the XIAP BIR3 domain. The top-ranked computational hits were conveniently synthesized employing Solid Phase Synthesis (SPS) on an alkane sulfonamide 'Safety-Catch' resin. This novel approach afforded the rapid synthesis of the target peptide library with high flexibility for the introduction of various C-terminal amide-capping groups. The library members were obtained in high yield (>65%) and purity (>85%), upon nucleophilic release from the activated resin by treatment with various amine nucleophiles. In vitro caspase-9 activity reconstitution assays of the peptides in the presence of the recombinant BIR3-domain of human XIAP (500nM) revealed N-methylalanyl-tertiarybutylglycinyl-4-(R)-phenoxyprolyl-N-biphenylmethyl carboxamide (11a) to be the most potent XIAP BIR3 antagonist of the series synthesized inducing 93% recovery of caspase-9 activity, when used at 1µM concentration. Compound (11a) also demonstrated moderate cytotoxicity against the breast cancer cell lines MDA-MB-231 and MCF-7, compared to the Smac/DIABLO-derived wild-type peptide sequences that were totally inactive in the same cell lines.

Binding and degradation of fibrinogen by Bacteroides fragilis and characterization of a 54 kDa fibrinogen-binding protein.

Bacteroides fragilis is a bacterium that resides in the normal human gastro-intestinal tract; however, it is also the most commonly isolated Gram-negative obligate anaerobe from human clinical infections, such as intra-abdominal abscesses, and the most common cause of anaerobic bacteraemia. Abscess formation is important in bacterial containment, limiting dissemination of infection and bacteraemia. In this study, we investigated B. fragilis binding and degradation of human fibrinogen, the major structural component involved in fibrin abscess formation. We have shown that B. fragilis NCTC9343 binds human fibrinogen. A putative Bacteroides fragilis fibrinogen-binding protein, designated BF-FBP, identified in the genome sequence of NCTC9343, was cloned and expressed in Escherichia coli. The purified recombinant BF-FBP bound primarily to the human fibrinogen Bbeta-chain. In addition, we have identified fibrinogenolytic activity in B. fragilis exponential phase culture supernatants, associated with fibrinogenolytic metalloproteases in NCTC9343 and 638R, and cysteine protease activity in YCH46. All nine clinical isolates of B. fragilis examined degraded human fibrinogen; with eight isolates, initial Aalpha-chain degradation was observed, with varying Bbeta-chain and gamma-chain degradation. With one blood culture isolate, Bbeta-chain and gamma-chain degradation occurred first, followed by subsequent Aalpha-chain degradation. Our data raise the possibility that the fibrinogen-binding protein of B. fragilis, along with a variety of fibrinogenolytic proteases, may be an important virulence factor that facilitates dissemination of infection via reduction or inhibition of abscess formation.

Dipeptide proline diphenyl phosphonates are potent, irreversible inhibitors of seprase (FAPalpha).

Dipeptidyl peptidase IV (DPP-IV) and seprase belong to a small group of membrane-bound, proline-specific serine proteases, the serine integral membrane proteases (SIMPs). Whilst DPP-IV is the most exhaustively studied peptidase in this class, relatively less is known about the inhibitor/substrate specificity of its close homolog seprase. Additionally, whereas, DPP-IV expression is largely ubiquitous, seprase expression is restricted to tumour and tissue remodelling sites in vivo. Consequently, the highly restricted expression and distribution of seprase potentially make it an excellent therapeutic target for the modulation of neoplastic invasion and metastasis. Against this background, we now wish to report on the design, synthesis, and kinetic testing of a series of dipeptide proline diphenyl phosphonates, against DPP-IV and seprase. The most potent inhibitor of DPP-IV and seprase was found to be Gly-ProP(OPh)2, which exhibited overall second-order rate constants of inactivation of 5.24 x 105 M-1 min-1 and 1.06 x 104 M-1 min-1 against DPP-IV and seprase, respectively. Both proteases displayed differing profiles of susceptibility towards the other members of the series of inhibitors synthesised. In addition, Gly-ProP(OPh)2 and Tyr-ProP(OPh)2 were found to exert a considerable, dose-dependent anti-invasive effect on the LOX melanoma cell line, in vitro.

Cathepsin S expression: An independent prognostic factor in glioblastoma tumours--A pilot study.

Cysteine proteinases have been implicated in astrocytoma invasion. We recently demonstrated that cathepsin S (CatS) expression is up-regulated in astrocytomas and provided evidence for a potential role in astrocytoma invasion (Flannery et al., Am J Path 2003;163(1):175-82). We aimed to evaluate the significance of CatS in human astrocytoma progression and as a prognostic marker. Frozen tissue homogenates from 71 patients with astrocytomas and 3 normal brain specimens were subjected to ELISA analyses. Immunohistochemical analysis of CatS expression was performed on 126 paraffin-embedded tumour samples. Fifty-one astrocytoma cases were suitable for both frozen tissue and paraffin tissue analysis. ELISA revealed minimal expression of CatS in normal brain homogenates. CatS expression was increased in grade IV tumours whereas astrocytoma grades I-III exhibited lower values. Immunohistochemical analysis revealed a similar pattern of expression. Moreover, high-CatS immunohistochemical scores in glioblastomas were associated with significantly shorter survival (10 vs. 5 months, p = 0.014). With forced inclusion of patient age, radiation dose and Karnofsky score in the Cox multivariate model, CatS score was found to be an independent predictor of survival. CatS expression in astrocytomas is associated with tumour progression and poor outcome in glioblastomas. CatS may serve as a useful prognostic indicator and potential target for anti-invasive therapy.

Cystic fibrosis sputum stimulates CD18-independent neutrophil migration across endothelial cells.

Excessive neutrophil recruitment to the lung underlies inflammatory-mediated lung damage in cystic fibrosis (CF). Neutrophils can migrate to the lung using either a CD18-dependent or CD18-independent mechanism. To determine if one of these migratory pathways is preferentially utilized by neutrophils migrating to the CF airways, this study examined the CD18 dependency of neutrophil transendothelial migration stimulated by the soluble fraction of CF sputum (SOL). Results demonstrate the preferential use of the CD18-independent migratory mechanism by both control and CF neutrophils and suggest that selective blocking of the CD18-independent migration pathway may offer a means of decreasing neutrophil influx to the CF airways.