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Protein kinase C-θ (PKCθ) is a member of the novel PKC subfamily known for its selective and predominant expression in T lymphocytes where it regulates essential functions required for T cell activation and proliferation. Our previous studies provided a mechanistic explanation for the recruitment of PKCθ to the center of the immunological synapse (IS) by demonstrating that a proline-rich (PR) motif within the V3 region in the regulatory domain of PKCθ is necessary and sufficient for PKCθ IS localization and function. Herein, we highlight the importance of Thr335-Pro residue in the PR motif, the phosphorylation of which is key in the activation of PKCθ and its subsequent IS localization. We demonstrate that the phospho-Thr335-Pro motif serves as a putative binding site for the peptidyl-prolyl cis-trans isomerase (PPIase), Pin1, an enzyme that specifically recognizes peptide bonds at phospho-Ser/Thr-Pro motifs. Binding assays revealed that mutagenesis of PKCθ-Thr335-to-Ala abolished the ability of PKCθ to interact with Pin1, while Thr335 replacement by a Glu phosphomimetic, restored PKCθ binding to Pin1, suggesting that Pin1-PKCθ association is contingent upon the phosphorylation of the PKCθ-Thr335-Pro motif. Similarly, the Pin1 mutant, R17A, failed to associate with PKCθ, suggesting that the integrity of the Pin1 N-terminal WW domain is a requisite for Pin1-PKCθ interaction. In silico docking studies underpinned the role of critical residues in the Pin1-WW domain and the PKCθ phospho-Thr335-Pro motif, to form a stable interaction between Pin1 and PKCθ. Furthermore, TCR crosslinking in human Jurkat T cells and C57BL/6J mouse-derived splenic T cells promoted a rapid and transient formation of Pin1-PKCθ complexes, which followed a T cell activation-dependent temporal kinetic, suggesting a role for Pin1 in PKCθ-dependent early activation events in TCR-triggered T cells. PPIases that belong to other subfamilies, i.e., cyclophilin A or FK506-binding protein, failed to associate with PKCθ, indicating the specificity of the Pin1-PKCθ association. Fluorescent cell staining and imaging analyses demonstrated that TCR/CD3 triggering promotes the colocalization of PKCθ and Pin1 at the cell membrane. Furthermore, interaction of influenza hemagglutinin peptide (HA307–319)-specific T cells with antigen-fed antigen presenting cells (APCs) led to colocalization of PKCθ and Pin1 at the center of the IS. Together, we point to an uncovered function for the Thr335-Pro motif within the PKCθ-V3 regulatory domain to serve as a priming site for its activation upon phosphorylation and highlight its tenability to serve as a regulatory site for the Pin1 cis-trans isomerase.

BACKGROUND Right-sided infective endocarditis (IE) related to intravenous drug use (IVDU) can follow an acute fulminant course. However, there is limited information on its longer-term clinical outcomes. AIM AND METHODS We assessed a cohort of consecutive patients who presented with IVDU complicated by severe tricuspid valve regurgitation to determine their presentation, treatment, and long-term outcomes. In this study, severe tricuspid regurgitation (TR) was defined by the European Association of Cardiovascular Imaging criteria at initial presentation to the hospital. RESULTS Thirty-three patients with a mean age of 35 ± 18 years (72% males) presented with IVDU associated with severe TR. At the initial presentation, 15 patients were in septic shock and required inotropes. 26 patients had septic pulmonary emboli; 10 patients had associated metastatic systemic sites of infection of which 5 patients had central nervous system (CNS) involvement. Three patients were in disseminated intravascular coagulation (DIC) and 1 patient had multi-organ failure (MOF), but not requiring dialysis or mechanical ventilation. Most patients had large tricuspid valve vegetations of >20mm. Eleven patients underwent surgery with 18% perioperative mortality. The Median follow-up was 6.4 years (0.5-11.4). Recurrent IE occurred in one-third of patients, the overall incidence of heart failure and Atrial fibrillation (AF) on follow-up was low in all 3 groups. Five-year survival was 94%. CONCLUSION Acute severe TR following associated endocarditis IVDU results in a fulminant initial presentation, but a longer-term prognosis is good with surgical and medical treatment.

The purpose of this study was to develop a simple and effective percutaneous approach to create tricuspid regurgitation in swine. Eleven pigs (71.68 ± 7.70 kg, 3 male) were involved in this study. A grasping forceps was introduced into the right ventricle through a steerable sheath under fluoroscopic guidance and used to disrupt the tricuspid valve apparatus by avulsing leaflet or chordae tendineae repeatedly. Transthoracic echocardiography and right ventricular angiography were used to evaluate the degree of tricuspid regurgitation created. Ten of the 11 pigs (90.91%) achieved severe tricuspid regurgitation and 1 (9.09%) obtained moderate tricuspid regurgitation immediately after the procedure. Heart rate of the pigs significantly increased immediately after tricuspid regurgitation creation compared to baseline (88.64 ± 23.24 vs. 76.00 ± 15.30 bpm, P = 0.02), but recovered to normal level at one month follow-up (77.09 ± 11.97 bpm, P = 0.85). The right atrium, tricuspid valve annulus, and right ventricle dilated obviously one month after tricuspid regurgitation creation (dimension changes: 3.01 ± 0.35 vs. 3.56 ± 0.40 cm, P = 0.02; 2.92 ± 0.36 vs. 3.37 ± 0.39 cm, P = 0.01; 3.06 ± 0.42 vs. 3.60 ± 0.47 cm, P = 0.03 respectively). Autopsy findings showed that rupture of leaflet and/or chordae tendineae finally led to the tricuspid regurgitation. Severe tricuspid regurgitation can be created by a simple and effective percutaneous approach with a grasping forceps in swine model and right heart dilation can be observed consistently at one-month follow-up. This model will be valuable in pre-clinical studies for developing new tricuspid valve repair or replacement technique to treat severe tricuspid regurgitation.

We reported that protein kinase C-η (PKCη) forms a novel (to our knowledge) signaling complex with the checkpoint inhibitory protein CTLA-4 in regulatory T cells (Tregs). This complex is required for the contact-dependent suppressive activity of Tregs, including suppression of antitumor immunity. However, the importance of PKCη in protective immunity mediated by T effector cells remains unclear. We used mice with germline or conditional Treg-specific deletion of Prkch, the PKCη-encoding gene, to explore CD8+ T cell–dependent antiviral immunity using the lymphocytic choriomeningitis virus Armstrong strain acute infection model as well as the in vitro activation of murine or human CD8+ T cells. Five days following infection, germline Prkch−/− mice displayed enhanced viral clearance compared with control mice. Similarly, Prkch Treg-specific conditional knockout mice also showed improved viral clearance and displayed enhanced expression of granzyme B and IFN-γ by both virus-specific and total CD8+ T cells, demonstrating that enhanced viral clearance in germline Prkch−/− mice is caused by PKCη deficiency in Tregs and the resulting functional defect of Prkch−/− Tregs. In addition, purified Prkch−/− mouse CD8+ T cells as well as PRKCH knockdown human CD8+ T cells displayed intact, or even enhanced, T cell activation in vitro as measured by proliferation and expression of granzyme B and IFN-γ. Thus, global PKCη deletion does not impair overall CD8+ T cell–mediated immunity, including antiviral immunity, implying that selective pharmacological PKCη inhibition could be safely used in vivo to inhibit undesired contact-dependent suppression by Tregs and, thus, enhance tumor-specific and, likely, virus-specific immunity.

Background and aim Cardiac sarcoma is a rare condition and may mimic atrial myxoma. We present a case report of a man with a cardiac sarcoma. Method Case report presentation. Results A 68-year-old man with a permanent pacemaker presented to us with a 4-month history of breathlessness. Echocardiography revealed a large right atrial mass adherent to the pacemaker lead and a provisional diagnosis of atrial myxoma was made based on echocardiographic appearance. A 60 x 30 x 30 mm irregular lobulated tumour was surgically resected from the right atrium. Upon histopathologic examination, the tumour was consistent with an undifferentiated pleomorphic sarcoma. Conclusion Cardiac sarcomas have an extremely poor prognosis and more unfortunately this man developed a surgical site infection and died of acute mediastinitis. We discuss the presentation, imaging and current surgical approaches to cardiac sarcoma. Curative treatment is currently limited for this disease.

There has been a resurgence of interest in the treatment of severe functional tricuspid regurgitation (FTR) due to the awareness of its poor outcomes and potential percutaneous therapies. Kay bicuspidization has been adapted in percutaneous therapies but its clinical outcome remains uncertain. The present study evaluates the efficacy of Kay repair in a novel ex vivo pulsatile system. Porcine tricuspid valve (TV) (n = 3) was extracted and incorporated into a patient-specific silicon right ventricle (RV) emulating severe FTR, on which Kay repair was subsequently performed. TV area metrics and RV hemodynamic assessment by means of stereo-scopic particle image velocimetry were quantified in both FTR and post-repair conditions. Bicuspidization led to significant increase in cardiac output although the overall increment due to this approach alone was generally small, possibly due to existence of residual TR and the large reduction in TV opening area. Kinetic energy and viscous loss levels were increased post-repair, especially during diastolic filling. Main vortex structures generally maintained post-procedural. However, there was enhanced swirling motion in larger RV domain. Although this might reduce mural-thrombus risk, the relatively more complex vortex phenomenon likely resulted in elevated viscous loss observed and may potentially impact long-term adaptation. The RV hemodynamic alteration after tricuspid repair could be used to predict the success of these future transcatheter solutions.

Objectives The impact of the COVID-19 pandemic on the treatment of patient with aortic valve stenosis is unknown and there is uncertainty on the optimal strategies in managing these patients. Methods This study is supported and endorsed by the Asia Pacific Society of Interventional Cardiology. Due to the inability to have face to face discussions during the pandemic, an online survey was performed by inviting key opinion leaders (cardiac surgeon/interventional cardiologist/echocardiologist) in the field of transcatheter aortic valve implantation (TAVI) in Asia to participate. The answers to a series of questions pertaining to the impact of COVID-19 on TAVI were collected and analyzed. These led subsequently to an expert consensus recommendation on the conduct of TAVI during the pandemic. Results The COVID-19 pandemic had resulted in a 25% (10-80) reduction of case volume and 53% of operators required triaging to manage their patients with severe aortic stenosis. The two most important parameters used to triage were symptoms and valve area. Periprocedural changes included the introduction of teleconsultation, preprocedure COVID-19 testing, optimization of protests, and catheterization laboratory set up. In addition, length of stay was reduced from a mean of 4.4 to 4 days. Conclusion The COVID-19 pandemic has impacted on the delivery of TAVI services to patients in Asia. This expert recommendation on best practices may be a useful guide to help TAVI teams during this period until a COVID-19 vaccine becomes widely available.

The global left ventricular (LV) contractility index, dσ*/dtmax measures the maximal rate of change in pressure-normalized LV wall stress. We aim to describe the trend of dσ*/dtmax in differing severity of aortic stenosis (AS) with preserved left ventricular ejection fraction (LVEF) and the association of dσ*/dtmax with clinical outcomes in moderate AS and severe AS. We retrospectively studied a total of 1738 patients with AS (550 mild AS, 738 moderate AS, 450 severe AS) and preserved LVEF ≥ 50% diagnosed from 1st January 2001 to 31st December 2015. dσ*/dtmax worsened with increasing severity of AS despite preserved LVEF (mild AS: 3.69 ± 1.28 s−1, moderate AS: 3.17 ± 1.09 s−1, severe AS: 2.58 ± 0.83 s−1, p dσ*/dtmax −1 was independently associated with a higher composite outcome of aortic valve replacement, congestive cardiac failure admissions and all-cause mortality (adjusted hazard ratio 1.48, 95% CI: 1.25–1.77, p dσ*/dtmax declined with worsening AS despite preserved LVEF. Low dσ*/dtmax −1 was independently associated with adverse clinical outcomes in moderate AS and severe AS with preserved LVEF.

The clinical and imaging differences between bicuspid aortic valve (BAV) and tricuspid aortic valve (TAV) patients with medically managed asymptomatic moderate-to-severe aortic stenosis (AS) have not been studied previously. We aim to characterize these differences and their clinical outcomes in this study. A retrospective observational study was conducted on 836 consecutive cases of isolated asymptomatic moderate-to-severe AS, with median follow-up of 3.4 years. Clinical and echocardiographic characteristics were compared between BAV and TAV patients. Subgroup analysis stratified by AS severity were performed. Survival analysis of all-cause mortality was performed using Kaplan-Meier curves and Cox proportional hazards model. Compared to BAV patients, TAV patients were older (76 ± 11 vs 55 ± 16 years, p0.001) and had more co-morbidities including hypertension (78% vs 56%; p0.001), diabetes (41% vs 24%; p0.001), and chronic kidney disease (20% vs 3%; p = 0.001). TAV patients had less severe aortic valve disease than BAV patients, with a higher aortic valve area index (0.71 ± 0.20 cm

Digoxin is a commonly prescribed drug in the management of heart failure and atrial fibrillation. Despite its widespread use, most clinicians have little experience with recognising clinical signs and symptoms that might suggest a potentially lethal drug toxicity. We herein describe two cases with specific reference to the electrocardiographic changes induced by digoxin and discuss the predisposing factors for toxicity, recognition of possible toxicity and treatment approaches.

We reported that protein kinase C-eta (PKCη) forms a novel signaling complex with the checkpoint inhibitory protein CTLA-4 in regulatory T cells (Tregs). This complex is required for the contact-dependent suppressive activity of Tregs, including suppression of anti-tumor immunity. However, the importance of PKCη in protective immunity mediated by T effector (Teff) cells remains unclear. We used mice with germline or conditional, Treg-specific deletion of Prkch, the PKCη-encoding gene, to explore CD8(+) T cell-dependent antiviral immunity using the lymphocytic choriomeningitis virus Armstrong strain acute infection model, as well as the in vitro activation of murine or human CD8(+) T cells. Five days following infection, germline Prkch(−/−) mice displayed enhanced viral clearance compared to control mice. Similarly, Prkch Treg-specific conditional knockout (cKO) mice also showed improved viral clearance and displayed enhanced expression of granzyme B (GzmB) and interferon-γ (IFNγ) by both virus-specific and total CD8(+) T cells, demonstrating that enhanced viral clearance in germline Prkch(−/−) mice is caused by PKCη deficiency in Tregs and the resulting functional defect of Prkch(−/−) Tregs. In addition, purified Prkch(−/−) mouse CD8(+) T cells as well as PRKCH knockdown human CD8(+) T cells displayed intact, or even enhanced, T cell activation in vitro as measured by proliferation and expression of GzmB and IFNγ. Thus, global PKCη deletion does not impair overall CD8(+) T cell-mediated immunity, including antiviral immunity, implying that selective pharmacological PKCη inhibition could be safely used in vivo to inhibit undesired contact-dependent suppression by Tregs and, thus, enhance tumor-specific and, likely, virus-specific immunity.

Studies have shown that medical therapy with renin-angiotensin blockers (RABs) may benefit patients with aortic stenosis (AS). However, its use and efficacy remains controversial, including in patients with low flow (LF) with preserved left ventricular ejection fraction (LVEF). We examined the effects of RAB use on LV remodeling in patients with severe AS with preserved LVEF, analyzing the differential effects in patients with LF compared with normal flow (NF). This is a retrospective study of 428 consecutive subjects from 2005 to 2014 with echocardiographic diagnosis of severe AS and preserved LVEF. Clinical and echocardiographic parameters were systematically collected and analyzed. Two hundred forty-two (57%) patients had LF. Sixty-four LF patients (26%) were treated with RAB. Patients on RAB treatment had a higher incidence of hyperlipidemia (69% vs 44%) and diabetes mellitus (53% vs 34%). Severity of AS in terms of valve area, transvalvular mean pressure gradient, and aortic valve resistance were similar between both groups as was the degree of LV diastolic function. The RAB group demonstrated significantly lower LV mass index with a correspondingly lower incidence of concentric LV hypertrophy. Regardless of the duration of RAB therapy, patients had increased odds of having a preserved LV mass index compared with those without RAB therapy. In conclusion, RAB therapy may be associated with less LV pathological remodeling and have a role in delaying patients from developing cardiovascular complications of AS.

Aims It remains unclear whether surgical or transcatheter mitral valve repair for secondary mitral regurgitation (MR) in patients with non-ischaemic cardiomyopathy reverse the underlying left ventricular (LV) pathophysiology. We hypothesized that mitral valve repair improves LV systolic function and forward flow and induces LV reverse remodelling in this group of patients. Methods and results Seventy-six patients (65 ± 14 years old, 43% male) with non-ischaemic cardiomyopathy and moderate to severe chronic secondary MR treated successfully with transcatheter or surgical mitral valve repair were evaluated. Transthoracic echocardiography was performed at baseline, discharge and 6 months post-repair. After mitral valve repair, LVEF, and LV global longitudinal strain (GLS) corrected for LV end-diastolic volume remained unchanged over time (P = 0.90 and P = 0.96, respectively). In contrast, LV forward flow increased significantly over time (stroke volume index: from 20 ± 7 to 29 ± 8 and 26 ± 8 mL/m2, P

A 38-year-old woman with suspected Marfan syndrome underwent an ascending aorta aneurysm repair with a David I valve-sparing procedure using a 26-mm Gelweave graft (Vascutek, Inchinnan, United Kingdom) 5 years previously [(1)][1]. Unfortunately, she developed progressively severe aortic valve

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.

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.

We present a case of a 75-year-old woman with cardiac dextroposition who presented for preoperative cardiac evaluation because of exertional dyspnoea. On examination, heart sounds were best appreciated on the right, and bowel sounds were heard over the left hemithorax. Electrocardiography showed widespread T-wave inversions. No coronary artery ischemia was found. A large congenital diaphragmatic hernia with displacement of the heart to the right was found on chest radiography and confirmed on computed tomography. Surgery was subsequently uneventful. In conclusion, thorough pulmonary auscultation to detect bowel sounds in the thorax increases clinical suspicion of cardiac dextroposition.

Pseudomonas aeruginosa is a dreaded pathogen in many clinical settings. Its inherent and acquired antibiotic resistance thwarts therapy. In particular, derepression of the AmpC β-lactamase is a common mechanism of β-lactam resistance among clinical isolates. The inducible expression of ampC is controlled by the global LysR-type transcriptional regulator (LTTR) AmpR. In the present study, we investigated the genetic and structural elements that are important for ampC induction. Specifically, the ampC (P ampC ) and ampR (P ampR ) promoters and the AmpR protein were characterized. The transcription start sites (TSSs) of the divergent transcripts were mapped using 5′ rapid amplification of cDNA ends-PCR (RACE-PCR), and strong σ 54 and σ 70 consensus sequences were identified at P ampR and P ampC , respectively. Sigma factor RpoN was found to negatively regulate ampR expression, possibly through promoter blocking. Deletion mapping revealed that the minimal P ampC extends 98 bp upstream of the TSS. Gel shifts using membrane fractions showed that AmpR binds to P ampC in vitro whereas in vivo binding was demonstrated using chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR). Additionally, site-directed mutagenesis of the AmpR helix-turn-helix (HTH) motif identified residues critical for binding and function (Ser38 and Lys42) and critical for function but not binding (His39). Amino acids Gly102 and Asp135, previously implicated in the repression state of AmpR in the enterobacteria, were also shown to play a structural role in P. aeruginosa AmpR. Alkaline phosphatase fusion and shaving experiments suggest that AmpR is likely to be membrane associated. Lastly, an in vivo cross-linking study shows that AmpR dimerizes. In conclusion, a potential membrane-associated AmpR dimer regulates ampC expression by direct binding.

Regulatory T (Treg) cells, which maintain immune homeostasis and self-tolerance, form an immunological synapse (IS) with antigen-presenting cells (APCs). However, signaling events at the Treg cell IS remain unknown. Here we show that the kinase PKC-η associated with CTLA-4 and was recruited to the Treg cell IS. PKC-η-deficient Treg cells displayed defective suppressive activity, including suppression of tumor immunity but not of autoimmune colitis. Phosphoproteomic and biochemical analysis revealed an association between CTLA-4-PKC-η and the GIT2-αPIX-PAK complex, an IS-localized focal adhesion complex. Defective activation of this complex in PKC-η-deficient Treg cells was associated with reduced depletion of CD86 from APCs by Treg cells. These results reveal a CTLA-4-PKC-η signaling axis required for contact-dependent suppression and implicate this pathway as a potential cancer immunotherapy target.

INTRODUCTION 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. METHODS 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. RESULTS Mean age was 76.8 years (61.0% male), mean body surface area 1.6 m2 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). CONCLUSION Despite the unique clinical differences in Asian populations, this registry demonstrated favourable mid-term clinical and safety outcomes in Asians undergoing TAVI.

The ability of Tregs to control the development of immune responses is essential for maintaining immune system homeostasis. However, Tregs also inhibit the development of efficient antitumor immune responses. Here we explored the characteristics and mechanistic basis of the Treg-intrinsic CTLA4-PKCη signaling pathway that we recently found to be required for contact-dependent Treg-mediated suppression. We show that PKCη is required for the Treg-mediated suppression of tumor immunity in vivo. The presence of PKCη-deficient (Prkch-/-) Tregs in the tumor microenvironment was associated with a significantly increased expression of the costimulatory molecule CD86 on intratumoral CD103+ DCs, enhanced priming of antigen-specific CD8+ T-cells, and greater levels of effector cytokines produced by these cells. Tumor development was reduced similarly in Treg-specific (Prkch-flox x Foxp3-Cre) and globally deficient recipients (Prkch-/-) as compared to wt mice, indicating that PKCη expression by effector cells is dispensable for the development of efficient anti-tumor responses. Similar to mouse Tregs, the GIT-PAK-PIX complex also operated downstream of CTLA4 and PKCη in human Tregs, and GIT2 knockdown in Tregs promoted antitumor immunity. We are now exploring the therapeutic impact of PKCη deletion in tumor-bearing mice using tamoxifen treatment of Prkch-flox x Foxp3-ERT2Cre and Prkch-flox x UBC-ERT2Cre mice as a surrogate for treatment with a highly selective and efficient PKCη inhibitor. Collectively, our data suggest that targeting the CTLA4-PKCη-GIT-PAK-PIX signaling pathway in Tregs could represent a novel immunotherapeutic strategy to alleviate the negative impact of Tregs on antitumor immune responses. Citation Format: Christophe Pedros, Hsin-Yu Liu, Ann J. Canonigo-Balancio, Kok-Fai Kong, Amnon Altman. Requirement of Treg-intrinsic CTLA4-PKCeta signaling pathway for suppressing tumor immunity [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A211.

The immunological synapse (IS) formed between immune cells and antigen-presenting cells (APCs) provides a platform for signaling. Protein kinase C (PKC)θ localizes in the T cell IS within the central supramolecular activation cluster (cSMAC), where it associates with CD28 and mediates T cell receptor (TCR)/CD28 signals leading to effector T (Teff) cell activation. In regulatory T (Treg) cells, PKCθ is sequestered away from the IS, and inhibits suppressive function. Other PKCs localizing in the IS mediate additional functions in various immune cells. Further work is needed to identify mechanisms underlying PKC recruitment or exclusion at the IS, potential redundancy among IS-localized PKCs, and the relevance of PKC localization for IS dynamics and lymphocyte activation.

The protein kinase C (PKC) family, discovered in the late 1970s, is composed of at least 10 serine/threonine kinases, divided into three groups based on their molecular architecture and cofactor requirements. PKC enzymes have been conserved throughout evolution and are expressed in virtually all cell types; they represent critical signal transducers regulating cell activation, differentiation, proliferation, death, and effector functions. PKC family members play important roles in a diverse array of hematopoietic and immune responses. This review covers the discovery and history of this enzyme family, discusses the roles of PKC enzymes in the development and effector functions of major hematopoietic and immune cell types, and points out gaps in our knowledge, which should ignite interest and further exploration, ultimately leading to better understanding of this enzyme family and, above all, its role in the many facets of the immune system.

Members of the PKC enzyme family play a critical role in diverse intracellular signaling pathways leading to cell proliferation, activation, differentiation, survival and death. Among the ten membe...

Signaling via the inducible costimulator ICOS fuels the stepwise development of follicular helper T cells (TFH cells). However, a signaling pathway unique to ICOS has not been identified. We found here that the kinase TBK1 associated with ICOS via a conserved motif, IProx, that shares homology with the tumor-necrosis-factor receptor (TNFR)-associated factors TRAF2 and TRAF3. Disruption of this motif abolished the association of TBK1 with ICOS, TRAF2 and TRAF3, which identified a TBK1-binding consensus. Alteration of this motif in ICOS or depletion of TBK1 in T cells severely impaired the differentiation of germinal center (GC) TFH cells and the development of GCs, interfered with B cell differentiation and disrupted the development of antibody responses, but the IProx motif and TBK1 were dispensable for the early differentiation of TFH cells. These results reveal a previously unknown ICOS-TBK1 signaling pathway that specifies the commitment of GC TFH cells.

Quorum sensing (QS) is a key regulator of virulence and biofilm formation in Pseudomonas aeruginosa and other medically relevant bacteria. Aqueous extracts of six plants, Conocarpus erectus , Chamaesyce hypericifolia , Callistemon viminalis , Bucida buceras , Tetrazygia bicolor , and Quercus virginiana , were examined in this study for their effects on P. aeruginosa virulence factors and the QS system. C. erectus , B. buceras , and C. viminalis caused a significant inhibition of LasA protease, LasB elastase, pyoverdin production, and biofilm formation. Additionally, each plant presented a distinct effect profile on the las and rhl QS genes and their respective signaling molecules, suggesting that different mechanisms are responsible for efficacy. Extracts of all plants caused the inhibition of QS genes and QS-controlled factors, with marginal effects on bacterial growth, suggesting that the quorum-quenching mechanisms are unrelated to static or cidal effects.

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.

Analysis of the serine-threonine phosphoproteome leads to the intriguing find that phosphorylation of the histone deacetylase HDAC7 is key to cytotoxic T lymphocyte function.

Protein kinase C (PKC) proteins are a group of well-conserved, intracellular signaling enzymes expressed in all cells and tissues, including immune cells. Much of the molecular insight into PKC immunobiology has been gleaned from studies using PKC gene (Prkc) knockout mice and the analysis of different disease models in these animals. More-recent studies have revealed that PKCs also have crucial roles in the pathogenesis of human immune disorders. Therefore, strategies to modulate the functions of PKC enzymes could have a major impact on the treatment and therapies of autoimmune diseases and other immune disorders.

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 advanced 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, which is important for Treg suppression. This resulted in PKCη localization in the Treg immunological synapse. These events promoted and were obligatory for 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 slow growing prostate adenocarcinoma TRAMP-C1 but, surprisingly, retained the ability to inhibit experimental autoimmune colitis, a disease that often occurs in cancer patients treated with checkpoint inhibitors. Moreover, PKCη loss in Treg cells increased the number of intratumoral CD4+ and CD8+ effector T cells without affecting Treg numbers, resulting in a significant increase of the intratumoral Teff:Treg cell ratio, a parameter considered to predict a better clinical outcome. 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. These findings establish the novel CTLA-4-PKCη signaling pathway as critical for suppressing tumor immunity, and implicate it as an attractive cancer immunotherapy target. Citation Format: Christophe Pedros, Kok-Fai Kong, Amnon Altman. Control of regulatory T (Treg) cell function by protein kinase C-eta (PKCη): A novel target for cancer immunotherapy [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr A148.

Protein kinase C-theta (PKCθ) is a protein kinase C (PKC) family member expressed predominantly in T lymphocytes, and extensive studies addressing its function have been conducted. PKCθ is the only T cell-expressed PKC that localizes selectively to the center of the immunological synapse (IS) following conventional T cell antigen stimulation, and this unique localization is essential for PKCθ-mediated downstream signaling. While playing a minor role in T cell development, early in vitro studies relying, among others, on the use of PKCθ-deficient ( Prkcq −/− ) T cells revealed that PKCθ is required for the activation and proliferation of mature T cells, reflecting its importance in activating the transcription factors nuclear factor kappa B, activator protein-1, and nuclear factor of activated T cells, as well as for the survival of activated T cells. Upon subsequent analysis of in vivo immune responses in Prkcq −/− mice, it became clear that PKCθ has a selective role in the immune system: it is required for experimental Th2- and Th17-mediated allergic and autoimmune diseases, respectively, and for alloimmune responses, but is dispensable for protective responses against pathogens and for graft- versus -leukemia responses. Surprisingly, PKCθ was recently found to be excluded from the IS of regulatory T cells and to negatively regulate their suppressive function. These attributes of PKCθ make it an attractive target for catalytic or allosteric inhibitors that are expected to selectively suppress harmful inflammatory and alloimmune responses without interfering with beneficial immunity to infections. Early progress in developing such drugs is being made, but additional studies on the role of PKCθ in the human immune system are urgently needed.

Inducible costimulator (ICOS) signaling fuels the stepwise development of T follicular helper (TFH) cells. However, a signaling pathway unique to ICOS has not been identified. We show that TANK-binding kinase 1 (TBK1) associates with ICOS via a conserved motif, IProx, which shares homology with tumor necrosis factor receptor (TNFR)-associated factors, TRAF2 and TRAF3. Disruption of this motif abolishes the association with TBK1, thus identifying a TBK1-binding consensus. Mutation of this motif in ICOS, or depletion of TBK1 in T cells severely impaired the differentiation of germinal center (GC) TFH, B cell and antibody responses, but was dispensable for early TFH differentiation. These results reveal a novel ICOS-TBK1 signaling pathway that specifies GC TFH cell commitment.

Modulating regulatory T (Treg) cell functions to specifically promote anti-tumor immune responses is a desirable strategy for cancer immunotherapy. Blockade of checkpoint molecules, CTLA-4 and PD-1, has proven clinical efficacy in advanced metastatic melanoma and other malignancies. We recently found that protein kinase C-eta (PKCη), a member of the PKC enzyme family, physically associated with CTLA-4, an inhibitory receptor highly expressed on Treg cells, which is important for Treg cell-mediated suppression. PKCη is recruited to the Treg cell immunological synapse, and mediates contact-dependent suppression by Treg cells. PKCη-deficient (Prkch-/-) Treg cells are defective in the suppression of anti-tumor immunity against B16 melanoma but retain the ability to control the development of autoimmune colitis. Here, we extended our findings regarding the importance of the CTLA-4-PKCη complex in contact-dependent Treg cell suppressive activity to an additional tumor model, i.e., the slow growing prostate adenocarcinoma TRAMP-C1, indicating that the novel CTLA-4-PKCη signaling pathway may be relevant to a broad spectrum of solid cancers. We further found that in the tumor microenvironment, the loss of PKCη in Treg cells substantially promoted the infiltration of CD4+ and CD8+ effector T cells without affecting the Treg cell numbers. As a result, there was a significant increase in the intratumoral CD8+ to Treg cell ratio, a parameter considered to be predictive of a better clinical outcome. Thus, our data reveal that the novel CTLA-4-PKCη signaling pathway, which we identified, is critical for suppressing anti-tumor immunity and, hence, implicate this pathway as an attractive cancer immunotherapy target for a broad spectrum of clinically debilitating malignancies. Citation Format: Christophe Pedros, Kok-Fai Kong, Amnon Altman. Control of regulatory T (Treg) cell function by protein kinase C-eta (PKCη): A novel target for cancer immunotherapy. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr B051.

Protein kinase Cθ (PKCθ) is a novel PKC that plays a key role in T lymphocyte activation. To understand how PKCθ is regulated in T cells, we investigated the properties of its N-terminal C2 domain that functions as an autoinhibitory domain. Our measurements show that a Tyr(P)-containing peptide derived from CDCP1 binds the C2 domain of PKCθ with high affinity and activates the enzyme activity of the intact protein. The Tyr(P) peptide also binds the C2 domain of PKCδ tightly, but no enzyme activation was observed with PKCδ. Mutations of PKCθ-C2 residues involved in Tyr(P) binding abrogated the enzyme activation and association of PKCθ with Tyr-phosphorylated full-length CDCP1 and severely inhibited the T cell receptor/CD28-mediated activation of a PKCθ-dependent reporter gene in T cells. Collectively, these studies establish the C2 domain of PKCθ as a Tyr(P)-binding domain and suggest that the domain may play a major role in PKCθ activation via its Tyr(P) binding.