Citations

AbstractBackgroundAppropriate time for ejection fraction (EF) reassessment after revascularization in patients with left ventricular dysfunction has not been investigated comprehensively, although 3 months after revascularization is recommended to stratify the risk of sudden cardiac death (SCD).HypothesisEF reassessed within different timeframe after revascularization may have incosistent contribution for risk stratification of SCD.MethodsPatients who had EF ≤ 40% before revascularization and had EF reassessment at least once during follow‐up were included. The role of early (<3 months) versus late (3–12 months) EF measurements in prediction of all‐cause mortality and SCD were compared.ResultsA total of 1589 patients were identified. EF reassessed <3 months was lower than EF reassessed within 3–12 months (42.1 ± 9.7% vs. 45.8 ± 10.8%; p < .01). Among 1069 patients who had EF reassessed <3 months, EF ≤ 35% was associated with a higher risk of all‐cause mortality (hazard ratio [HR], 1.67; 95% confidence interval [CI], 1.22–2.29; p < .01), but had no association with the risk of SCD (HR, 1.44; 95% CI, 0.84–2.48; p = .18). By contrast, among 595 patients who had EF reassessed within 3–12 months, EF ≤ 35% was associated with higher risks of both all‐cause death (HR, 1.81; 95% CI, 1.06–3.10; p = .03) and SCD (HR, 2.71; 95% CI, 1.31–5.61; p < .01). The relative contribution of SCD to all‐cause death was higher in patients with EF ≤ 35% than patients with EF > 35% when EF was reassessed within 3–12 months (p = .04). However, when EF was reassessed <3 months, the mode of death was similar in patients with EF ≤ 35% versus >35% (p = .85).Conclusions3 to 12 months after revascularization may be appropriate for cardiac function reassessment and SCD risk stratification.

Abstract TIGIT (T cell immunoreceptor with Ig and ITIM domains) is a co-inhibitory receptor, highly expressed by Tregs, and contributes to the suppressive function of Tregs by limiting pro-inflammatory Th1 and Th17 cell responses. Herein, we report that subsets of human regulatory B cells (Bregs) express surface TIGIT and can thus play a critical role in immune regulation. Using data from human B cell surface arrays and RNA-seq, we identified two major TIGIT+ human Bregs subsets, exhibiting CD24hiCD27+CD39hiIgD+IgMhiCD1chi marginal zone (MZ)-like and CD24hiCD27+CD39+IgD−IgM+CD1c+ memory Bregs. We further demonstrated that TIGIT+ Bregs were also capable of suppressing immune responses by their ability to express not only IL-10 and PD-L1, but also granzyme B and TGFb1. In addition, TIGIT+ Bregs can also suppress immune responses by altering dendritic cell functions. In line with these observations, liver allograft recipients with donor-specific alloantibody (DSA) had significantly lower numbers of TIGIT+ Bregs than those without DSA. Moreover, the frequency of TIGIT+ Bregs correlated with that of CD4+CD25+CD127lo Tregs, while it inversely correlated with the frequency of follicular helper T cells. We thus concluded that TIGIT+ Bregs play critical roles in immune regulation in liver allograft recipients.

Primary cilia are microtube-based organelles that extend from the cell surface and function as biochemical and mechanical extracellular signal sensors. Primary cilia coordinate a series of signaling pathways during development. Cilia dysfunction leads to a pleiotropic group of developmental disorders, termed ciliopathy. Phosphoinositides (PIs), a group of signaling phospholipids, play a crucial role in development and tissue homeostasis by regulating membrane trafficking, cytoskeleton reorganization, and organelle identity. Accumulating evidence implicates the involvement of PI species in ciliary defects and ciliopathies. The abundance and localization of PIs in the cell are tightly regulated by the opposing actions of kinases and phosphatases, some of which are recently discovered in the context of primary cilia. Here, we review several cilium-associated PI kinases and phosphatases, including their localization along cilia, function in regulating the ciliary biology under normal conditions, as well as the connection of their disease-associated mutations with ciliopathies.

Background: Autosomal dominant polycystic kidney disease (ADPKD) is a ciliopathy characterized by abnormal tubular epithelial proliferation and fluid secretion. Anoctamin 1 (ANO1) is a calcium-dependent chloride channel. However, how ANO1 contributes to ADPKD is largely unexplored. Methods: Kidney tissues from ADPKD patients, Pkd1RC/RC mice model, WT9-7 human PKD1+⁣/- cells, and 3D culture models in vitro were used. Localization of ANO1 and cilium length were investigated by confocal immunofluorescence. Results: We found that ANO1 was consistently upregulated in human and mouse PKD kidneys. Intriguingly, ANO1 located in a vesicle-like pattern at the ciliary base but not on the ciliary surface. ANO1 deficiency enhanced ciliogenesis and the ciliary dosage of polycystin-2 in human PKD cells, and reduced cyst formation in 3D culture models. Moreover, inhibition of ANO1 abolished the activation of STAT3 and ERK pathways in PKD cells. Conclusions: Our data indicate ANO1 is a negative regulator for both cilia length and cilia trafficking of polycystin-2 and provide mechanistic insights regarding the therapeutic potential of ANO1 pathway in ADPKD treatment.

Skeletal muscle atrophy is commonly associated with aging, immobilization, muscle unloading, and congenital myopathies. Generation of mature muscle cells from skeletal muscle satellite cells (SCs) is pivotal in repairing muscle tissue. Exercise therapy promotes muscle hypertrophy and strength. Primary cilium is implicated as the mechanical sensor in some mammalian cells, but its role in skeletal muscle cells remains vague. To determine mechanical sensors for exercise-induced muscle hypertrophy, we established three SC-specific cilium dysfunctional mouse models— Myogenic factor 5 ( Myf5 ) -Arf-like Protein 3 ( Arl3 ) −/− , Paired box protein Pax-7 ( Pax7 )- Intraflagellar transport protein 88 homolog ( Ift88 ) −/− , and Pax7-Arl3 −/− —by specifically deleting a ciliary protein ARL3 in MYF5-expressing SCs, or IFT88 in PAX7-expressing SCs, or ARL3 in PAX7-expressing SCs, respectively. We show that the Myf5-Arl3 −/− mice develop grossly the same as WT mice. Intriguingly, mechanical stimulation-induced muscle hypertrophy or myoblast differentiation is abrogated in Myf5-Arl3 −/− and Pax7-Arl3 −/− mice or primary isolated Myf5-Arl3 −/− and Pax7-Ift88 −/− myoblasts, likely due to defective cilia-mediated Hedgehog (Hh) signaling. Collectively, we demonstrate SC cilia serve as mechanical sensors and promote exercise-induced muscle hypertrophy via Hh signaling pathway.

Abstract Cellular senescence contributes to tissue homeostasis and age-related pathologies. However, how senescence is initiated in damaged cells remains vague. Here, we discover that irreparable stresses induce transient biogenesis of cilia, which are used by stressed cells to directly communicate with the promyelocytic leukemia nuclear bodies (PML-NBs), the validated stress signaling hub, to initiate senescence responses. Mechanistically, a ciliary ARL13B-ARL3 GTPase cascade negatively regulates the association of transition fiber protein FBF1 and SUMO-conjugating enzyme UBC9. Irreparable stresses downregulate the ciliary ARLs to release UBC9, which SUMOylates FBF1 at the ciliary base. SUMOylated FBF1 then translocates to PML-NBs to promote PML-NB-dependent senescence initiation. Remarkably, Fbf1 suppression effectively subdues global senescence burden and prevents associated health-span decline in irradiation-treated mice. Collectively, our findings assign primary cilia a central role in inducing senescence program and identify them as promising targets to dampen senescence-associated detrimental damage in future senotherapy strategies.

Background: Heart failure (HF) with improved ejection fraction (HFiEF) is defined as a new subset in addition to the subsets of HF with reduced EF (≤40%; HFrEF) and HF with preserved EF (>40%). The characteristics and outcomes of patients with ischemic HFiEF after coronary revascularization are unknown. Methods and Results: We identified 1,816 patients with coronary artery diseases and reduced EF (≤40%) in a large hospital in China, who underwent either coronary artery bypass graft surgery (n=1,126) or percutaneous coronary intervention with drug eluting stent (n=687) from January 2005 to December 2014. All patients had EF reassessment during follow-up. The improvement of EF peaked at 3 months and persisted for more than one year after revascularization. Thus, 589 patients who had EF reassessment between 3 to 12 months after revascularization were included in the definitions of HFiEF and HFrEF patient cohort and subsequent survival analysis. 367 (62.3%) patients had EF >40% which constituted HFiEF cohort while 222 (37.7%) patients with EF≤40% constituted HFrEF cohort. Using stepwise logistic regression, we identified preoperative EF (odds ratio [OR], 1.06; 95% confidence interval [CI], 1.02-1.11; P =0.006), left ventricular end-systolic diameter (OR, 0.93; 95% CI, 0.91-0.95; P =0.000) and history of myocardial infarction (OR, 0.61; 95% CI, 0.42-0.88; P =0.008) were associated with being in HFiEF group. Using Cox proportional hazard models, HFiEF patients had lower risk of all-cause mortality (hazard ratios [HR], 0.39; 95% CI, 0.23-0.68; P =0.001), sudden cardiac death (HR, 0.32; 95% CI, 0.14-0.75; P =0.009) and death due to HF (HR, 0.13; 95% CI, 0.03-0.52; P =0.004) compared to HFrEF patients. Nonproportional outcome of composite end points (i.e., combination of all-cause mortality, HF hospitalization and repeat revascularization) between HFiEF and HFrEF groups was detected by using the Schoenfeld residuals. By using flexible parametric model, patients with HFiEF had similar risk of composite end points in the first 5 years (HR, 0.84; 95% CI, 0.53-1.31; P =0.433), but significantly lower risk during years 6 to 11(HR, 0.12; 95% CI, 0.03-0.56; P =0.007). In the HFiEF group, the risk of death were age (HR, 1.07; 95% CI, 1.02-1.12; P =0.008), current smoking (HR, 5.62; 95% CI, 1.93-18.18; P =0.002) and history of myocardial infarction (HR, 2.89; 95% CI, 1.05-7.93; P =0.039). By contrast, in the HFrEF group, the risk factors were moderate or severe mitral regurgitation (HR, 1.81; 95% CI, 1.06-3.11; P =0.031) and estimated glomerular filtration rate (HR, 0.97; 95% CI, 0.95-0.99; P=0.014). Conclusions: Patients with ischemic HFiEF have distinct clinical characteristics and favorable outcomes. Our data support HFiEF as a distinct HF category in ischemic HF patients after revascularization therapy.

HYLS1 regulates the ciliary phosphoinositide and hedgehog pathways, implicating a novel pathogenic mechanism for HLS syndrome.

The mechanisms underlying E‐cadherin clustering and AJ maturation are not fully understood although the E‐cadherin‐mediated formation of adherens junctions (AJs) is essential for the morphogenesis of epithelial cells. Here we report that the association between type Iγ phosphatidylinositol phosphate kinase (PIPKIγ) and Exo70 regulated the transport and clustering of Ecadherin on the plasma membrane and, subsequently, the extension of nascent E‐cadherin adhesions. We also observed that PI4,5P(2) accumulation at E‐cadherin clusters during the assembly of E‐cadherin adhesions. PIPKIγ‐generated PI4,5P(2) is required for recruiting Exo70 to newly formed E‐cadherin junctions and facilitates the assembly and maturation of AJs. Additionally, Rho activity and actin structure were impaired by loss of Exo70 and/or PIPKIγ. These results support a model in which PIPKIγ and PIPKIγ‐generated PI4,5P(2) pools at nascent E‐cadherin contacts cue Exo70 targeting and orients the tethering of exocyst‐associated E‐cadherin. This could be an important mechanism that regulates E‐cadherin clustering and AJ maturation, and actin reorganization, which is essential for the establishment of solid, polarized epithelial structures.

Although the immune checkpoint role of programmed death ligand 1 (PD-L1) has been established and targeted in cancer immunotherapy, the tumor-intrinsic role of PD-L1 is less appreciated in tumor biology and therapeutics development, partly because of the incomplete mechanistic understanding. Here we demonstrate a potentially novel mechanism by which PD-L1 promotes the epithelial-mesenchymal transition (EMT) in triple-negative breast cancer (TNBC) cells by suppressing the destruction of the EMT transcription factor Snail. PD-L1 directly binds to and inhibits the tyrosine phosphatase PTP1B, thus preserving p38-MAPK activity that phosphorylates and inhibits glycogen synthase kinase 3β (GSK3β). Via this mechanism, PD-L1 prevents the GSK3β-mediated phosphorylation, ubiquitination, and degradation of Snail and consequently promotes the EMT and metastatic potential of TNBC. Significantly, PD-L1 antibodies that confine the tumor-intrinsic PD-L1/Snail pathway restricted TNBC progression in immunodeficient mice. More importantly, targeting both tumor-intrinsic and tumor-extrinsic functions of PD-L1 showed strong synergistic tumor suppression effect in an immunocompetent TNBC mouse model. Our findings support that PD-L1 intrinsically facilitates TNBC progression by promoting the EMT, and this potentially novel PD-L1 signaling pathway could be targeted for better clinical management of PD-L1–overexpressing TNBCs.