Transcatheter aortic valve implantation (TAVI) is an effective treatment for high-risk or inoperative patients with severe aortic stenosis. Given the unique characteristics of Asian populations, ...questions regarding mid-term outcomes in Asians undergoing TAVI have yet to be addressed. We evaluated the two-year clinical outcomes of TAVI in an Asian population using Valve Academic Research Consortium-2 definitions.
This prospective study recruited 59 patients from a major academic medical centre in Singapore. The main outcomes were two-year survival rates, peri-procedural complications, symptom improvement, valvular function and assessment of learning curve.
Mean age was 76.8 years (61.0% male), mean body surface area 1.6 m
and mean logistic EuroSCORE 18.7%. Survival was 93.2%, 86.0% and 79.1% at 30 days, one year and two years, respectively. At 30 days post TAVI, the rate of stroke was 1.7%, life-threatening bleeding 5.1%, acute kidney injury 25.0%, major vascular complication 5.1%, and new permanent pacemaker implantation 6.8%. 29.3% of TAVI patients were rehospitalised (47.1% cardiovascular-related) within one year. These composite outcomes were measured: device success (93.2%); early safety (79.7%); clinical efficacy (66.1%); and time-related valve safety (84.7%). Univariate analysis found these predictors of two-year all-cause mortality: logistic EuroSCORE (hazard ratio HR 1.07; p < 0.001); baseline estimated glomerular filtration rate (HR 0.97; p = 0.048); and acute kidney injury (HR 5.33; p = 0.022). Multivariate analysis identified non-transfemoral TAVI as a predictor of cardiovascular-related two-year mortality (HR 14.64; p = 0.008).
Despite the unique clinical differences in Asian populations, this registry demonstrated favourable mid-term clinical and safety outcomes in Asians undergoing TAVI.
Right ventricle to pulmonary artery (RV-PA) conduits have been used for the surgical repair of congenital heart defects. These conduits frequently become stenosed or develop insufficiency with time, ...necessitating reoperations. Percutanous pulmonary valve implantation (PPVI) can delay the need for repeated surgeries in patients with congenital heart defects and degenerated RV-PA conduits. We presented our first experience with PPVI and described in detail the procedural methods and the considerations that are needed for this intervention to be successful. Immediate and short-term clinical outcomes of our patients were reported. Good haemodynamic results were obtained, both angiographically and on echocardiography. PPVI provides an excellent alternative to repeat open-heart surgery for patients with congenital heart defects and degenerated RV-PA conduits. This represents a paradigm shift in the management of congenital heart disease, which is traditionally managed by open-heart surgery.
Abstract
Our previous studies revealed a critical role of a novel CTLA4-PKCη signaling in mediating the suppressive activity of Tregs in antitumor immunity. Here, we extended these findings into a ...biologically and clinically more relevant context. We have analyzed the role of PKCη in antitumor immunity in intact tumor-bearing mice with Treg− or CD8+ T cell-specific Prkch deletion, including in a therapeutic model of combinatorial treatment. Using two models of mouse transplantable cancer and a genetically engineered autochthonous hepatocellular carcinoma (HCC) model, we found that mice with Treg-specific Prkch deletion displayed a significantly reduced growth of B16-F10 melanoma and TRAMP-C1 adenocarcinoma tumors. Tumor growth reduction was associated with a less immunosuppressive tumor microenvironment, indicated by increased numbers and function of tumor-infiltrating CD8+ T cells and elevated expression of the costimulatory ligand CD86 on CD103+ DCs. In contrast, CD8+ T cell-specific Prkch deletion had no effect on tumor growth and the abundance or functionality of CD8+ T cells. Similar beneficial antitumor effects were found in mice with germline or Treg-specific Prkch deletion that were induced to develop an autochthonous HCC. Lastly, using a therapeutic model, we found that monotherapies consisting of Treg-specific Prkch deletion or vaccination with irradiated Flt3L-expressing B16-F10 tumor cells post-tumor implantation significantly delayed tumor growth. This effect was more pronounced in mice receiving a combination of the two immunotherapies. These findings demonstrate the potential utility of PKCη inhibition as a viable clinical approach to treat cancer patients, especially when combined with adjuvant therapies.
Funded by the NIH grant 5R01CA233862
Abstract
Modulating regulatory T cell (Treg) function to promote anti-tumor immunity is a desirable strategy for cancer immunotherapy. Blockade of checkpoint molecules CTLA-4 and PD-1 has shown ...clinical efficacy in metastatic melanoma and other malignancies. We recently reported that Treg stimulation induced the recruitment of protein kinase C-eta (PKCη), together with the GIT-PAK-PIX signaling complex that mediates focal adhesion disassembly, to CTLA-4, an inhibitory receptor highly expressed on Foxp3+ Tregs and important for Treg suppression. As a result, PKCη was recruited to the immunological synapse of stimulated Treg. These events promoted Treg-mediated contact-dependent suppression, including suppression of tumor immunity, via a mechanism likely involving depletion of costimulatory CD80/86 ligands from APCs (Nat Immunol. 2014;15:465–72).
PKCη-deficient (PKCη−/−) Tregs were defective in the suppression of anti-tumor immunity against B16 melanoma and the prostate adenocarcinoma TRAMP-C1 but retained the ability to inhibit experimental colitis, a disease that often occurs in patients treated with anti-CTLA-4 antibodies. PKCη loss in mouse Treg cells increased both the number of intratumoral CD4+ and CD8+ effector T cells and their ability to produce cytokines upon restimulation. Moreover, shRNA-mediated knockdown of PKCη reduced the suppressive activity of human Tregs. Impaired activation of the GIT-PAK-PIX complex and the resulting defect in CD80/86 depletion are likely responsible for the defective suppressive activity of PKCη−/− Tregs. Altogether, our findings establish the CTLA-4-PKCη signaling pathway as critical for suppressing tumor immunity, and implicate it as an attractive cancer immunotherapy target.
Protein kinase C-θ (PKC-θ) translocates to the center of the immunological synapse, but the underlying mechanism and its importance in T cell activation are unknown. Here we found that the V3 domain ...of PKC-θ was necessary and sufficient for localization to the immunological synapse mediated by association with the coreceptor CD28 and dependent on the kinase Lck. We identified a conserved proline-rich motif in V3 required for association with CD28 and immunological synapse localization. We found association with CD28 to be essential for PKC-θ-mediated downstream signaling and the differentiation of T helper type 2 cells (T(H)2 cells) and interleukin 17-producing helper T cells (T(H)17 cells) but not of T helper type 1 cells (T(H)1 cells). Ectopic expression of V3 sequestered PKC-θ from the immunological synapse and interfered with its functions. Our results identify a unique mode of CD28 signaling, establish a molecular basis for the immunological synapse localization of PKC-θ and indicate V3-based 'decoys' may be therapeutic modalities for T cell-mediated inflammatory diseases.
Pseudomonas aeruginosa is the major pathogen associated with morbidity and mortality of patients with cystic fibrosis. One of the reasons for the failure of β-lactam antibiotic regimens appears to be ...mediated by de-regulation of the
ampC gene, encoding the chromosomal Ambler's Class C β-lactamase. Currently, the AmpC is the only known chromosomal β-lactamase whose expression is regulated by a transcriptional regulator, AmpR. We generated an
ampC mutation in the prototypic
P. aeruginosa strain PAO1. The mutation in
ampC did not abolish the β-lactamase activity entirely suggesting the expression of yet another unreported β-lactamase. Our genomic analysis revealed the presence of an open reading frame encoding a protein with high homology to the Class D β-lactamases, commonly known as oxacillinases. The gene was named
poxB for
Pseudomonas oxacillinase. Cloning and expression of
poxB in
Escherichia coli conferred β-lactam resistance to the host. We detected the presence of
poxB both in clinical and environmental isolates. Our studies show that
P. aeruginosa possesses two β-lactamases, AmpC and PoxB, which contribute to its resistance against a wide spectrum of β-lactam antibiotics.
Abstract
We previously reported that protein kinase C-eta plays an important role in the contact-dependent suppressive activity of Tregs via its association with CTLA4, and that PKC-eta-deficient ...(Prkch−/−) Tregs fail to suppress anti-melanoma tumor immunity. Here we extend this study to a genetically engineered mouse model of HCC driven by CRISPR-Cas9-driven deletion of Pten and p53. In the Pten-p53 HCC model, Prkch Treg-specific conditional knockout (cKO) mice developed a lower tumor incidence, fewer tumors, lower degree of steatosis phenotype, and showed higher intratumoral CD4+ T cells than WT mice. In addition, B cells and resident DCs displayed higher levels of the costimulatory ligand CD86 in dLNs of cKO mice. Increased CD4+ T cells, memory T lymphocytes, and cytokines production were observed in spleen of cKO mice. These results indicate that Treg-expressed PKC-eta is required for Treg-mediated suppression of anti-HCC tumor immunity. To further explore the importance of PKC-eta in Teff cells, the LCMVArm acute infection model, as well as the in vitro activation of murine or human CD8+ T cells were used. We found that purified Prkch−/− mouse CD8+ T cells as well as PRKCH knockdown human CD8+ T cells displayed intact T cell activation in vitro as measured by proliferation and expression of GzmB and IFNg. Interestingly, Treg-specific cKO mice showed improved viral clearance and displayed enhanced expression of GzmB and IFNg by virus-specific CD8+ T cells. Thus, global PKC-eta deletion does not impair overall CD8+ T cell-mediated immunity implying that selective pharmacological PKC-eta inhibition could be safely used in vivo to inhibit undesired contact-dependent suppression by Tregs and, thus, enhance tumor- and viral-specific immunity.
Abstract
Our earlier work has revealed a novel, Treg-intrinsic signaling pathway consisting of a CTLA4 and PKC-eta complex, which is required for Treg function to suppress immune responses, including ...tumor-specific immunity, in a contact-dependent manner, but is dispensable for suppressions mediated by suppressive cytokines (Nat. Immunol. 2014; J. Clin. Invest. Insight. 2017). Furthermore, we found PKC-eta to be dispensable for the activation and effector function of mouse and human CD8+ T cells, implying that PKC-eta is a promising cancer immunotherapy target, whose pharmacological inhibition would inhibit the suppressive activity of tumor-specific Tregs without impairing function of tumor-specific cytotoxic T cells. We therefore initiated, in collaboration with Takeda Oncology, the testing of two lead small molecule compounds previously reported to selectively inhibit the catalytic activity of Ca2+-independent PKC subfamily members, including PKC-eta. Using in vitro assays, we titrated these compounds and established a range of compound concentrations that significantly inhibited the in vitro contact-dependent suppressive activity of human Tregs, while only minimally inhibiting the activation and proliferation of conventional human T cells. Furthermore, they did not inhibit the production of IL-10 by stimulated human Tregs, consistent with our hypothesis that the CTLA4-PKC-eta signaling pathway is selectively required for contact-dependent suppression. Such compounds could potentially serve as a novel form of CTLA4-based checkpoint blockade for cancer immunotherapy and, at the same time, minimize immune-related adverse effects associated with clinically used anti-CTLA4 antibodies.
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