Takotsubo syndrome: State-of-the-art review by an expert panel - Part 1

Takotsubo syndrome (TTS) is an acute cardiac condition independent of epicardial coronary obstruction that mimics acute coronary syndrome and is characterized by acute heart failure with reversible ventricular motion abnormalities. This consensus paper is the result of a multinational effort aiming to summarize the current state of the art on TTS. Experts in the field provide a thorough and detailed review of this syndrome. Several novel and unique sections are emphasized in this document, including the current state of the art on genetics of takotsubo syndrome, microRNAs (miRs), racial differences, role of cardiac spectroscopy and intracoronary imaging, as well as mechanical circulatory support. In part 1 of this two-part manuscript, we discuss how TTS came to be known, several patterns and forms it can take in patients, epidemiology and pathophysiology of the syndrome, and clinical presentation.

High-density lipoprotein cholesterol as a therapeutic target for residual risk in patients with acute coronary syndrome

Objective

The current guideline recommends lowering low-density lipoprotein cholesterol (LDL-C) for the primary management of dyslipidemia in patients at high-risk of cardiovascular events. Patients who have achieved LDL-C levels below the recommended targets may still experience cardiovascular events, suggesting additional therapeutic targets beyond LDL-C. The aim of this study was to investigate whether high-density lipoprotein cholesterol (HDL-C) levels had an impact on plaque stabilization in patients with acute coronary syndrome (ACS).

Methods

This study consisted of 90 ACS patients with untreated dyslipidemia. In optical coherence tomography (OCT) analysis, a plaque with fibrous cap thickness ≦160 μm was defined as a high-risk plaque. We registered one high-risk plaque per one patient by baseline OCT imaging, and then administrated high-intensity statin. Based on the follow-up OCT results, patients whose registered plaque was no longer high-risk plaque were classified into a responder group and the remains into a non-responder group.

Results

No differences were observed in the baseline LDL-C and HDL-C levels between the two groups. Reduction of LDL-C levels (δ LDL-C: −53 ± 21 mg/dL vs. −42 ± 29 mg/dL, p = 0.036) and increase of HDL-C levels (δ HDL-C: 2.5 ± 5.9 mg/dL vs. −0.3 ± 6.7 mg/dL, p = 0.039) were greater in the responder group. On multivariate logistic regression analysis, δ LDL-C levels (OR: 0.956, 95% CI: 0.921–0.993; p = 0.020) and δ HDL-C levels (OR: 1.143; 95% CI: 1.005–1.300, p = 0.041) were independent contributors for plaque stabilization.

Conclusions

Increase of HDL-C levels is associated with plaque stabilization in patients with ACS. HDL-C could be a therapeutic target for residual risk management.

Functional characterization of recombinant snake venom rhodocytin: rhodocytin mutant blocks CLEC-2/podoplanin-dependent platelet aggregation and lung metastasis

Essentials We generated recombinant rhodocytin that could aggregate platelets via CLEC-2. Recombinant wild-type rhodocytin formed heterooctamer with four α- and β-subunits. Asp 4 in α-subunit of rhodocytin was required for binding to CLEC-2. Inhibitory mutant of rhodocytin blocked podoplanin-dependent hematogenous metastasis.

SUMMARY

Background Rhodocytin, a disulfide-linked heterodimeric C-type lectin from Calloselasma rhodostoma consisting of α-subunits and β-subunits, induces platelet aggregation through C-type lectin-like receptor 2 (CLEC-2). CLEC-2 is a physiological binding partner of podoplanin (PDPN), which is expressed on some tumor cell types, and is involved in tumor cell-induced platelet aggregation and tumor metastasis. Thus, modified rhodocytin may be a possible source of anti-CLEC-2 drugs for both antiplatelet and antimetastasis therapy. However, its molecular function has not been well characterized, because of the lack of recombinant rhodocytin that induces platelet aggregation. Objective To produce recombinant rhodocytin, in order to verify its function with mutagenesis, and to develop an anti-CLEC-2 drug based on the findings. Methods We used Chinese hamster ovary cells to express recombinant rhodocytin (wild-type [WT] and mutant), which was analyzed for induction/inhibition of platelet aggregation with light transmission aggregometry, the formation of multimers with blue native PAGE, and binding to CLEC-2 with flow cytometry. Finally, we investigated whether mutant rhodocytin could suppress PDPN-induced metastasis in an experimental lung metastasis mouse model. Results Functional WT] rhodocytin (αWTβWT) was obtained by coexpression of both subunits. Asp4 in α-subunits of rhodocytin was required for CLEC-2 binding. αWTβWT formed a heterooctamer similarly to native rhodocytin. Moreover, an inhibitory mutant of rhodocytin (αWTβK53A/R56A), forming a heterotetramer, bound to CLEC-2 without inducing platelet aggregation, and blocked CLEC-2-PDPN interaction-dependent platelet aggregation and experimental lung metastasis. Conclusion These findings provide molecular characterization information on rhodocytin, and suggest that mutant rhodocytin could be used as a therapeutic agent to target CLEC-2.

Biological application of water-based electrochemically synthesized CuO leaf-like arrays: SERS response modulated by the positional isomerism and interface type

Cupric oxide leaf-like nanostructures (CuONSs) (average dimensions: 80-180 nm in width and 400-750 nm in length) were synthesized via anodic electrochemical dissolution of copper in an ethanol solution containing LiCl electrolyte and water. Ultraviolet-visible (UV-Vis), Fourier-transform infrared (FT-IR), and Raman spectroscopies as well as scanning electron microscope (SEM), high-resolution transmission electron microscopy with energy dispersive X-ray (HD-TEM-EDS), X-ray photoelectron spectroscopy (XPS), and X-ray powder diffraction (XRD) were used to explore the metal surface plasmon, size, rheology, and structure of CuONSs. Then, pyridine α-aminophosphinic acid isomers (α-, β-, and γ-NHPy) were synthesized and assembled on the CuONS/air and CuONS/aqueous solution interfaces at the pH level of solution = 7. Differences in adsorption and thus in the spectral response resulting from positional isomerism were examined by surface-enhanced Raman scattering (SERS) with an excitation wavelength of 785 nm. The manner of interaction of the investigated isomers with CuONSs in an aqueous solution was discussed in detail and compared with that at the CuONS/air interface. For γ-NHPy, at the CuONS/water interface, the time-dependent changes in the spectral profile were observed and analyzed. For β-NHPy at the CuONS/air interface, tip-enhanced Raman scattering (TERS) measurements were performed. These measurements allowed observing single molecule behavior and avoiding interference from the molecule's surrounding environment.

Crystalline structure of pulverized dental calculus induces cell death in oral epithelial cells

BACKGROUND AND OBJECTIVE

Dental calculus is a mineralized deposit attached to the tooth surface. We have shown that cellular uptake of dental calculus triggers nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation, leading to the processing of the interleukin-1β precursor into its mature form in mouse and human phagocytes. The activation of the NLRP3 inflammasome also induced a lytic form of programmed cell death, pyroptosis, in these cells. However, the effects of dental calculus on other cell types in periodontal tissue have not been investigated. The aim of this study was to determine whether dental calculus can induce cell death in oral epithelial cells.

MATERIAL AND METHODS

HSC-2 human oral squamous carcinoma cells, HOMK107 human primary oral epithelial cells and immortalized mouse macrophages were exposed to dental calculus or 1 of its components, hydroxyapatite crystals. For inhibition assays, the cells were exposed to dental calculus in the presence or absence of cytochalasin D (endocytosis inhibitor), z-YVAD-fmk (caspase-1 inhibitor) or glyburide (NLRP3 inflammasome inhibitor). Cytotoxicity was determined by measuring lactate dehydrogenase (LDH) release and staining with propidium iodide. Tumor necrosis factor-α production was quantified by enzyme-linked immunosorbent assay. Oral epithelial barrier function was examined by permeability assay.

RESULTS

Dental calculus induced cell death in HSC-2 cells, as judged by LDH release and propidium iodide staining. Dental calculus also induced LDH release from HOMK107 cells. Following heat treatment, dental calculus lost its capacity to induce tumor necrosis factor-α in mouse macrophages, but could induce LDH release in HSC-2 cells, indicating a major role of inorganic components in cell death. Hydroxyapatite crystals also induced cell death in both HSC-2 and HOMK107 cells, as judged by LDH release, indicating the capacity of crystal particles to induce cell death. Cell death induced by dental calculus was significantly inhibited by cytochalasin D, z-YVAD-fmk and glyburide, indicating NLRP3 inflammasome involvement. In permeability assays, dental calculus attenuated the barrier function of HSC-2 cell monolayers.

CONCLUSION

Dental calculus induces pyroptotic cell death in human oral epithelial cells and the crystalline structure plays a major role in this process. Oral epithelial cell death induced by dental calculus might be important for the etiology of periodontitis.