Deciphering Immune Landscape Remodeling Unravels the Underlying Mechanism for Synchronized Muscle and Bone Aging.

Evidence from numerous studies has revealed the synchronous progression of aging in bone and muscle; however, little is known about the underlying mechanisms. To this end, human muscles and bones are harvested and the aging-associated transcriptional dynamics of two tissues in parallel using single-cell RNA sequencing are surveyed. A subset of lipid-associated macrophages (triggering receptor expressed on myeloid cells 2, TREM2+ Macs) is identified in both aged muscle and bone. Genes responsible for muscle dystrophy and bone loss, such as secreted phosphoprotein 1 (SPP1), are also highly expressed in TREM2+ Macs, suggesting its conserved role in aging-related features. A common transition toward pro-inflammatory phenotypes in aged CD4+ T cells across tissues is also observed, activated by the nuclear factor kappa B subunit 1 (NFKB1). CD4+ T cells in aged muscle experience Th1-like differentiation, whereas, in bone, a skewing toward Th17 cells is observed. Furthermore, these results highlight that degenerated myocytes produce BAG6-containing exosomes that can communicate with Th17 cells in the bone through its receptor natural cytotoxicity triggering receptor 3 (NCR3). This communication upregulates CD6 expression in Th17 cells, which then interact with TREM2+ Macs through CD6-ALCAM signaling, ultimately stimulating the transcription of SPP1 in TREM2+ Macs. The negative correlation between serum exosomal BCL2-associated athanogene 6 (BAG6) levels and bone mineral density further supports its role in mediating muscle and bone synchronization with aging.

Multi-Proteomic Analysis Reveals the Effect of Protein Lactylation on Matrix and Cholesterol Metabolism in Tendinopathy.

Tendinopathy is a disease with surging prevalence. Lacking understanding of molecular mechanisms impedes the development of therapeutic approaches and agents. Lysine lactylation (Kla) is a newly discovered post-translational modification related to glycolysis. It has long been noted that manipulation of glycolysis metabolism could affect tendon cell function, tendon homeostasis, and healing process of tendon. However, protein lactylation sites in tendinopathy remain unexplored. Here, we conducted the first proteome-wide Kla analysis in tendon samples harvested from patients with rotator cuff tendinopathy (RCT), which identified 872 Kla sites across 284 proteins. Compared with normal counterparts, 136 Kla sites on 77 proteins were identified as upregulated in the pathological tendon, while 56 sites on 32 proteins were downregulated. Function enrichment analysis demonstrated that the majority of proteins with upregulated Kla levels functioned in organization of the tendon matrix and cholesterol metabolism, accompanied by lower expression levels which meant impaired cholesterol metabolism and degeneration of the tendon matrix, indicating potential cross-talk between protein lactylation and expression levels. At last, by western blotting and immunofluorescence, we verified the correlation between high lactylation and the downregulation of matrix and cholesterol-related proteins including BGN, MYL3, TPM3, and APOC3. ProteomeXchange: PXD033146.

Delayed denervation-induced muscle atrophy in Opg knockout mice.

Recent evidence has shown a crucial role for the osteoprotegerin/receptor activator of nuclear factor κ-B ligand/RANK (OPG/RANKL/RANK) signaling axis not only in bone but also in muscle tissue; however, there is still a lack of understanding of its effects on muscle atrophy. Here, we found that denervated Opg knockout mice displayed better functional recovery and delayed muscle atrophy, especially in a specific type IIB fiber. Moreover, OPG deficiency promoted milder activation of the ubiquitin-proteasome pathway, which further verified the protective role of Opg knockout in denervated muscle damage. Furthermore, transcriptome sequencing indicated that Opg knockout upregulated the expression of Inpp5k, Rbm3, and Tet2 and downregulated that of Deptor in denervated muscle. In vitro experiments revealed that satellite cells derived from Opg knockout mice displayed a better differentiation ability than those acquired from wild-type littermates. Higher expression levels of Tet2 were also observed in satellite cells derived from Opg knockout mice, which provided a possible mechanistic basis for the protective effects of Opg knockout on muscle atrophy. Taken together, our findings uncover the novel role of Opg in muscle atrophy process and extend the current understanding in the OPG/RANKL/RANK signaling axis.

Dolutegravir Plus Lamivudine Dual-Drug Regimen in Treatment-Naive HIV-1-Infected Patients With High-Level Viral Load: Preliminary Data From the Real World.

BACKGROUND: Some inpatients with HIV-RNA ≥500,000 copies/mL in China need to use 2-drug regimen for some reasons, although limited data are available for dolutegravir plus lamivudine (3TC) in those patients with ultra-high viral loads. METHODS: We conducted a single-center retrospective-prospective study in China and enrolled 42 ART-naive HIV-infected inpatients who use a once-daily 2-drug regimen because of various reasons (drug interaction, renal impairment, age, and other related comorbidities).They were divided into 2 groups, low viral load group (baseline viral load <500,000 copies/mL, n = 20) and high viral load group (baseline viral load ≥500,000 copies/mL, n = 22). All patients were followed up for 48 weeks. RESULTS: The median of baseline viral load was 5.74 log10 copies/mL and CD4+ T-cell count was 59 cells/µL. At week 48, there was no significant difference (P = 0.598) in proportions of participants with HIV-1 RNA <50 copies/mL [90%, 95% confidence interval (CI) (75.6% to 104.4%) in low viral load groups vs 95.5%, 95% CI (86.0% to 104.9%) in high viral load groups]. No differences were found in mean increase of CD4+ T-cell count from baseline between 2 groups (218 ± 122 vs 265 ± 127 cells/µL, P = 0.245). There is no grade 3 or higher treatment-related adverse events and none discontinued treatment because of adverse events. CONCLUSIONS: The results of our study in real world support dolutegravir + 3TC dual regimen as a promising therapy option for treatment-naive HIV-infected patient with baseline viral load ≥500,000 copies/mL.

Higher Risk of Dyslipidemia With Coformulated Elvitegravir, Cobicistat, Emtricitabine, and Tenofovir Alafenamide than Efavirenz, Lamivudine, and Tenofovir Disoproxil Fumarate Among Antiretroviral-Naive People Living With HIV in China.

BACKGROUND: We aimed to examine the evolution of blood lipids and compare the risk of dyslipidemia between antiretroviral-naive people living with HIV who received tenofovir disoproxil fumarate (TDF), lamivudine (3TC), and efavirenz (EFV) (TDF + 3TC + EFV) and those who received coformulated elvitegravir, cobicistat, emtricitabine, and tenofovir alafenamide (E/C/F/TAF). METHODS: We retrospectively reviewed the medical records of 2343 antiretroviral-naive people living with HIV who initiated TDF + 3TC + EFV or E/C/F/TAF. A propensity score matching method was used to compare longitudinal changes of blood lipids between the 2 groups. RESULTS: By using 1:3 matching ratio, we included 253 and 91 matched patients in TDF + 3TC + EFV group and E/C/F/TAF group, respectively. The levels of total cholesterol, triglyceride, low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol were higher in E/C/F/TAF group than those in TDF + 3TC + EFV group at 3, 6, 9, and 12 months (Wilcoxon test, all Ps < 0.05), except for high-density lipoprotein cholesterol at 9 and 12 months. The cumulative rates of hypercholesterolemia, hypertriglyceridemia, and high LDL-C in PLWH with normal lipid levels in E/C/F/TAF group were higher than those in TDF + 3TC + EFV group (hypercholesterolemia, 59.7% vs 21.5%, P < 0.001; hypertriglyceridemia, 69.5% vs 46.3%, P < 00.001; and high LDL-C, 41.5% vs 14.2%, P < 0.001). Multivariate analysis showed treatment with E/C/F/TAF was associated with a significantly higher risk of hypercholesterolemia [adjusted hazard ratio (HR), 4.12; 95% confidence interval (CI): 2.65 to 6.41], hypertriglyceridemia (adjusted HR, 1.69; 95% CI: 1.18 to 2.43), and high LDL-C (adjusted HR, 4.60; 95% CI: 2.66 to 7.97). CONCLUSIONS: We concluded that treatment with E/C/F/TAF resulted in higher risks of dyslipidemia compared with TDF + 3TC + EFV.

A Single-Cell Survey of Cellular Heterogeneity in Human Great Saphenous Veins.

BACKGROUND: The great saphenous vein (GSV) is the most commonly used conduit for coronary arterial bypass graft. However, the status of the GSV, including metabolic dysfunction such as diabetes mellitus (DM) complication, is strongly associated with vein graft failure (VGF). To date, the molecular mechanism underlying VGF remains elusive. Detailed characterization of the cellular components and corresponding expression regulation in GSVs would be of great importance for clinical decision making to reduce VGF. METHODS: To this end, we performed single-cell RNA sequencing to delineate cellular heterogeneity in three human GSV samples. RESULTS: Scrutinization of cellular composition and expression revealed cell diversity in human GSVs, particularly endothelial cells (ECs). Our results unraveled that functional adaptation drove great expression differences between venous ECs and valvular ECs. For instance, cell surface receptor ACKR1 demarcated venous Ecs, whereas ACRK3/ACKR4 were exclusively expressed by valvular ECs. Differential gene expression analysis suggested that genes highly expressed in venous ECs were mainly involved in vasculature development and regulation of leukocyte adhesion, whereas valvular ECs have more pronounced expression of genes participating in extracellular matrix organization, ossification and platelet degranulation. Of note, pseudo-time trajectory analysis provided in silico evidence indicating that venous ECs, valvular ECs and lymphatic vessels were developmentally connected. Further, valvular ECs might be an importance source for lymphatic vessel differentiation in adults. Additionally, we found a venous EC subset highly expressing IL6, which might be associated with undesirable prognosis. Meanwhile, we identified a population of ANGPTL7+ fibroblasts (FBs), which may be profibrotic and involved in insulin resistance in human GSVs. Additionally, our data suggest that immune cells only accounted for a small fraction, most of which were macrophages. By assessing the intertwined remodeling in metabolic dysfunction that potentially increases the gene expression regulatory network in mural cells and leukocytes, we found that transcription factor KLF9 likely operated a proinflammatory program, inducing the transcription of metallothionein proteins in two mural cell subsets and proinflammatory immune cells. Lastly, cellular communication analysis revealed that proinflammatory signaling, including TRAIL, PVR, CSF and GDF, were uniquely activated in patients with metabolic dysfunction. CONCLUSIONS: Our results identified critical cell-specific responses and cellular interactions in GSVs. Beyond serving as a repertoire, this work illustrates multifactorial likelihood of VGF.

Novel Risk Prediction Model to Determine Adverse Heart Failure Outcomes in Arrhythmogenic Right Ventricular Cardiomyopathy.

Background Patients with arrhythmogenic right ventricular cardiomyopathy are at risk for life-threatening ventricular tachyarrhythmias, but progressive heart failure (HF) may occur in later stages of disease. This study aimed to characterize potential risk predictors and develop a model for individualized assessment of adverse HF outcomes in arrhythmogenic right ventricular cardiomyopathy. Methods and Results Longitudinal and observational cohorts with 290 patients with arrhythmogenic right ventricular cardiomyopathy from the Fuwai Hospital in Beijing, China, and 99 patients from the University Heart Center in Zurich, Switzerland, with follow-up data were studied. The primary end point of the study was heart transplantation or death attributable to HF. The model was developed by Cox regression analysis for predicting risk and was internally validated. During 4.92±3.03 years of follow-up, 48 patients reached the primary end point. The determinants of the risk prediction model were left ventricular ejection fraction, serum creatinine levels, moderate-to-severe tricuspid regurgitation, and atrial fibrillation. Implantable cardioverter-defibrillators did not reduce the occurrence of adverse HF outcomes. Conclusions A novel risk prediction model for arrhythmogenic right ventricular cardiomyopathy has been developed using 2 large and well-established cohorts, incorporating common clinical parameters such as left ventricular ejection fraction, serum creatinine levels, tricuspid regurgitation, and atrial fibrillation, which can identify patients who are at risk for terminal HF events, and may guide physicians to assess individualized HF risk and to optimize management strategies.

Low rate of pre-exposure prophylaxis and post-exposure prophylaxis uptake and high prevalence of transmitted drug resistance among newly diagnosed primary HIV infections in Shenzhen, China: a real-world retrospective study.

BACKGROUND: Understanding the characteristics of newly diagnosed primary human deficiency virus-1 (HIV-1) infection in the context of the post-antiretroviral therapy era and HIV drug prophylaxis is essential for achieving the new target of 95-95-95-95 by 2025. This study reported the characteristics of newly diagnosed primary HIV-1 infection in Shenzhen. METHODS: This is a real-world retrospective study. Eighty-seven newly diagnosed primary HIV-1-infected patients were recruited from January 2021 to March 2022 at the Third People's Hospital of Shenzhen. Demographic, epidemiological, diagnostic, drug resistance, and medical data were described and analyzed. RESULTS: Overall, 96.6% (84/87) of the newly identified primary HIV-1-infected patients were male, including 88.5% (77/87) men have sex with men (MSM), with a median age of 29.0 years (Q1-Q3: 24.0-34.0 years); of these, 85.1% (74/87) reported high-risk sexual behaviors with casual partners. The rate of condom usage was only 28.7% (25/87). The overall rate of pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP) was 8.0% (7/87, including 4 PrEP and 3 PEP cases) around the potential exposure, although 41.4% of the patients had prior awareness of such interventions. Moreover, only 19.5% (17/87) had previously used PrEP or PEP. Of those, 58.8% (10/17) of the patients obtained drugs from the internet, and only 35.3% (6/17) reported good compliance. A total of 54.0% (47/87) of subjects were diagnosed by the HIV nucleic acid test. Acute retroviral syndrome appeared in 54.0% (47/87) of patients. The prevalence of transmitted drug resistance (TDR) mutation was 33.9% (19/56), including 6 (10.7%) against nucleoside reverse transcriptase inhibitor (NRTI) plus non-nucleoside reverse transcriptase inhibitor (NNRTI), 8 (14.3%) against NNRTI, and 5 (8.9%) against protease inhibitor (PI) only. CONCLUSIONS: Owing to the low utilization rate and incorrect usage of PrEP and PEP, massive efforts are needed to promote HIV-preventive strategies in the MSM population. The extremely high prevalence of TDR mutation in this population implies the need for future pretreatment drug resistance surveillance.

Resolving the intertwining of inflammation and fibrosis in human heart failure at single-cell level.

Inflammation and fibrosis are intertwined mechanisms fundamentally involved in heart failure. Detailed deciphering gene expression perturbations and cell-cell interactions of leukocytes and non-myocytes is required to understand cell-type-specific pathology in the failing human myocardium. To this end, we performed single-cell RNA sequencing and single T cell receptor sequencing of 200,615 cells in both human dilated cardiomyopathy (DCM) and ischemic cardiomyopathy (ICM) hearts. We sampled both lesion and mild-lesion tissues from each heart to sequentially capture cellular and molecular alterations to different extents of cardiac fibrosis. By which, left (lesion) and right ventricle (mild-lesion) for DCM hearts were harvest while infarcted (lesion) and non-infarcted area (mild-lesion) were dissected from ICM hearts. A novel transcription factor AEBP1 was identified as a crucial cardiac fibrosis regulator in ACTA2+ myofibroblasts. Within fibrotic myocardium, an infiltration of a considerable number of leukocytes was witnessed, especially cytotoxic and exhausted CD8+ T cells and pro-inflammatory CD4+ T cells. Furthermore, a subset of tissue-resident macrophage, CXCL8hiCCR2+HLA-DRhi macrophage was particularly identified in severely fibrotic area, which interacted with activated endothelial cell via DARC, that potentially facilitate leukocyte recruitment and infiltration in human heart failure.

Performance of Xpert MTB/RIF Ultra for the Diagnosis of Pulmonary Tuberculosis Using Bronchoalveolar Lavage Samples in People Living with HIV/AIDS (PLWHA) in China: A Prospective Study.

BACKGROUND: Sputum is commonly used for the diagnostic testing of pulmonary tuberculosis (PTB), but people living with HIV/AIDS (PLWHA) usually have little sputum. Moreover, the automated molecular test, Xpert MTB/RIF assay (Xpert), has a low sensitivity in PLWHA. We aimed to estimate the performance of Xpert Ultra on the detection of Mycobacterium tuberculosis (MTB) using bronchoalveolar lavage (BAL). METHODS: From February 5, 2018 to March 30, 2019, a total of 99 PLWHA with suspected PTB at the Third People's Hospital of Shenzhen, China, were recruited. The information on demographics and medical history, blood MTB antigen-specific interferon gamma enzyme-linked immunospot assay (T-SPOT.TB), T lymphocyte subsets, and plasma HIV RNA load were collected. Computed tomography (CT) and flexible bronchoscopy were performed, and BAL and blood samples were collected. Testing of acid-fast bacilli (AFB), tuberculosis real-time fluorescence quantitative PCR (TBDNA), Ultra, Xpert, and MTB culture were conducted. RESULTS: Compared to BAL MTB culture for tuberculosis diagnosis, Ultra, Xpert, T-SPOT.TB, TBDNA and AFB smear had the sensitivity of 0.96 (24/25), 0.80 (20/25), 0.84 (21/25), 0.44 (11/25), and 0.12 (3/25), respectively; and the specificity of 0.92 (68/74), 0.96 (71/74), 0.93 (69/74), 0.96 (71/74), and 0.99 (73/74), respectively. Our study found that the sensitivity of Ultra was higher than that of culture and Xpert (AUC 0.92, 0.86 and 0.84, respectively). The results also indicated that PLWHA with CD4 <200 cells/mm3 had reduced both sensitivity (from 1.00 and 0.86 to 0.94 and 0.78, respectively) and specificity (from 0.96 and 1.00 to 0.90 and 0.41, respectively) of Ultra and Xpert for the diagnosis of PTB. DISCUSSION: Our data supported an increased sensitivity of Ultra compared to that of Xpert on BAL samples of PLWHA, regardless of the CD4 counts and reference diagnosis standards.

A Global Phosphorylation Atlas of Proteins Within Pathological Site of Rotator Cuff Tendinopathy.

Rotator cuff tendinopathy (RCT) is the most common cause of shoulder pain, therefore posing an important clinical problem. Understanding the mechanism and biochemical changes of RCT would be of crucial importance and pave the path to targeting novel and effective therapeutic strategies in translational perspectives and clinical practices. Phosphorylation, as one of the most important and well-studied post-translational modifications, is tightly associated with protein activity and protein functional regulation. Here in this study, we generated a global protein phosphorylation atlas within the pathological site of human RCT patients. By using Tandem Mass Tag (TMT) labeling combined with mass spectrometry, an average of 7,741 phosphorylation sites (p-sites) and 3,026 proteins were identified. Compared with their normal counterparts, 1,668 p-sites in 706 proteins were identified as upregulated, while 73 p-sites in 57 proteins were downregulated. GO enrichment analyses have shown that majority of proteins with upregulated p-sites functioned in neutrophil-mediated immunity whereas downregulated p-sites are mainly involved in muscle development. Furthermore, pathway analysis identified NF-κB-related TNF signaling pathway and protein kinase C alpha type (PKCα)-related Wnt signaling pathway were associated with RCT pathology. At last, a weighted kinase-site phosphorylation network was built to identify potentially core kinase, from which serine/threonine-protein kinase 39 (STLK3) and mammalian STE20-like protein kinase 1 (MST1) were proposed to be positively correlated with the activation of Wnt pathway.

Multicentre derivation and validation of a prognostic scoring system for mortality assessment in HIV-infected patients with talaromycosis.

BACKGROUND: Although the widespread use of modern antiretroviral therapy (ART) has reduced the incidence of talaromycosis in people living with HIV, mortality remains as high as 20% in this population, even after appropriate antifungal treatment. OBJECTIVES: The objective of our study was to develop a risk assessment system for HIV-infected patients with comorbid talaromycosis, in order to provide these patients with appropriate, effective and potentially life-saving interventions at an early stage of their illness. PATIENTS/METHODS: This was a multicentre, retrospective cohort study conducted in China. We built a predictive model based on data from 11 hospitals, and a validated model using the data of 1 hospital located in an endemic area. RESULTS: Forward stepwise multivariate statistical calculations indicated that age, aspartate aminotransferase/alanine transaminase ratio and albumin levels, and BUN levels were valid, independent predictors of the risk of death in HIV-infected patients with talaromycosis. Our developed and validated risk scoring system is effective for the identification of HIV-infected patients with talaromycosis at high risk of death at hospital admission (p < .001; AUC = 0.860). In our study, our risk prediction model provided functional and robust discrimination in the validation cohort (p < .001; AUC = 0.793). CONCLUSION: The prognostic scoring system for mortality assessment developed in the present study is an easy-to-use clinical tool designed to accurately assist clinicians in identifying high-risk patients with talaromycosis.

Evolution of blood lipids and risk factors of dyslipidemia among people living with human immunodeficiency virus who had received first-line antiretroviral regimens for 3 years in Shenzhen.

BACKGROUND: Lipid abnormalities are prevalent among people living with human immunodeficiency virus (HIV) (PLWH) and contribute to increasing risk of cardiovascular events. This study aims to investigate the incidence of dyslipidemia and its risk factors in PLWH after receiving different first-line free antiretroviral regimens. METHODS: PLWH who sought care at the Third People's Hospital of Shenzhen from January 2014 to December 2018 were included, and the baseline characteristics and clinical data during the follow-up were collected, including total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C). The risk factors of dyslipidemia after antiretroviral therapy were analyzed with the generalized estimating equation model. RESULTS: Among the 7623 PLWH included, the mean levels of TC, HDL-C and LDL-C were 4.23 ±â€Š0.85 mmol/L, 1.27 ±â€Š0.29 mmol/L and 2.54 ±â€Š0.65 mmol/L, respectively, and the median TG was 1.17 (IQR: 0.85-1.68) mmol/L. Compared with that in PLWH receiving tenofovir disoproxil fumarate (TDF) + lamivudine (3TC) + ritonavir-boosted lopinavir (LPV/r), zidovudine (AZT) + 3TC + efavirenz (EFV), and AZT + 3TC + LPV/r, the incidence of dyslipidemia was lower in PLWH receiving TDF + 3TC + EFV. In multivariate analysis, we found that the risks of elevations of TG, TC, and LDL-C were higher with TDF + 3TC + LPV/r (TG: odds ratio [OR] = 2.82, 95% confidence interval [CI]: 2.55-3.11, P < 0.001; TC: OR = 1.24, 95% CI: 1.14-1.35, P < 0.001; LDL: OR = 1.06, 95% CI: 1.00-1.12, P = 0.041), AZT + 3TC + EFV (TG: OR = 1.41, 95% CI: 1.28-1.55, P < 0.001; TC: OR = 1.43, 95% CI: 1.31-1.56, P < 0.001; LDL: OR = 1.18, 95% CI: 1.12-1.25, P < 0.001), and AZT + 3TC + LPV/r (TG: OR = 3.08, 95% CI: 2.65-3.59, P < 0.001; TC: OR = 2.40, 95% CI: 1.96-2.94, P < 0.001; LDL: OR = 1.52, 95% CI: 1.37-1.69, P < 0.001) than with TDF + 3TC + EFV, while treatment with TDF + 3TC + LPV/r was less likely to restore HDL-C levels compared with TDF + 3TC + EFV (OR = 0.95, 95% CI: 0.92-0.97, P < 0.001). In addition to antiretroviral regimens, antiretroviral therapy duration, older age, overweight, obesity and other traditional factors were also important risk factors for dyslipidemia. CONCLUSION: The incidence of dyslipidemia varies with different antiretroviral regimens, with TDF + 3TC + EFV having lower risk for dyslipidemia than the other first-line free antiretroviral regimens in China.

The homozygous variant c.245G > A/p.G82D in PNPLA2 is associated with arrhythmogenic cardiomyopathy phenotypic manifestations.

Arrhythmogenic cardiomyopathy (ACM) is a familial cardiomyopathy featured by fibrofatty replacement of cardiomyocytes. Responsible genetic factors are not discernible in approximately one-third of ACM probands. To investigate this further, we performed whole genome sequencing in 14 mutation-negative ACM probands who underwent cardiac transplantation, and we identified one ACM proband with a rare homozygous missense variant in PNPLA2 (c.245G > A, p.G82D), a rate-limiting enzyme that hydrolyzes triglycerides into fatty acids and diacylglycerol. Bioinformatic analysis suggested that this missense variant may lead to loss of function and therefore impair lipid catabolism. Genetic screening in this proband's family also inferred that the homozygous variant cosegregated with disease. To validate the pathogenicity of this variant and confirm its association with ACM, we established a knockin mouse model carrying the orthologous human homozygous PNPLA2 variant. Interestingly, mice with the homozygous variant presented with arrhythmias and significant cardiac dysfunction at 12 weeks, whereas heterozygous mice were not affected. Moreover, those homozygous mice suffered sudden death and/or heart failure by the age of 14 weeks. Pathological examination showed that extensive lipogenesis in cardiomyocytes and cardiac fibrosis were prominent in the myocardium. Herein, our data demonstrated that the homozygous missense variant PNPLA2 (c.245G > A, p.G82D) associated with a recessive form of ACM.

Clinical Characteristics of Patients with a Right Ventricular Thrombus in Arrhythmogenic Right Ventricular Cardiomyopathy.

BACKGROUND: Thrombus formation within the left ventricle (LV) is a well-known clinical entity and is often associated with underlying myocardial disease, whereas right ventricular (RV) thrombi are rarely observed. This study aimed to investigate the clinical characteristics of patients with arrhythmogenic RV cardiomyopathy (ARVC) who developed an RV thrombus. METHODS AND RESULTS: This study included patients with an RV thrombus from the ARVC databases of the University Heart Center in Zurich, Switzerland, and the Fuwai Hospital in Beijing, China. In total, there were 13 ARVC patients who had an RV thrombus detected. The mean age was 33 ± 15 (range: 11-51) years. Eight patients (62%) were male. The mean Task Force score was 6 ± 1. Nine of these patients (69%) had an RV thrombus only whereas four patients had biventricular thrombi. All 13 ARVC patients had a severely impaired RV function (RV fractional area change 16 ± 9% and RV ejection fraction 15 ± 4%); LV ejection fraction (LVEF) was 40 ± 15%. ARVC patients with an additional LV thrombus had a lower LVEF than the others (24 ± 11 vs. 47 ± 11, p = 0.02). Under therapeutic anticoagulation, complete thrombus resolution was observed in 9/13 patients (69%). CONCLUSION: RV thrombus formation is a potential complication of ARVC with impaired RV function. In patients with biventricular involvement, thrombi may also occur within the LV. Anticoagulation is generally effective to dissolve RV thrombi. This study highlights the need for awareness during cardiac imaging to detect this rare complication of ARVC.

A novel genotype-based clinicopathology classification of arrhythmogenic cardiomyopathy provides novel insights into disease progression.

AIMS: Arrhythmogenic cardiomyopathy (AC) shows large heterogeneity in its clinical, genetic, and pathological presentation. This study aims to provide a comprehensive atlas of end-stage AC and illustrate the relationships among clinical characteristics, genotype, and pathological profiles of patients with this disease. METHODS AND RESULTS: We collected 60 explanted AC hearts and performed standard pathology examinations. The clinical characteristics of patients, their genotype and cardiac magnetic resonance imaging findings were assessed along with pathological characteristics. Masson staining of six representative sections of each heart were performed. Digital pathology combined with image segmentation was developed to calculate distribution of myocardium, fibrosis, and adipose tissue. An unsupervised clustering based on fibrofatty distribution containing four subtypes was constructed. Patients in Cluster 1 mainly carried desmosomal mutations (except for desmoplakin) and were subjected to transplantation at early age; this group was consistent with classical 'desmosomal cardiomyopathy'. Cluster 2 mostly had non-desmosomal mutations and showed regional fibrofatty replacement in right ventricle. Patients in Cluster 3 showed parallel progression, and included patients with desmoplakin mutations. Cluster 4 is typical left-dominant AC, although the genetic background of these patients is not yet clear. Multivariate regression analysis revealed precordial QRS voltage as an independent indicator of the residual myocardium of right ventricle, which was validated in predicting death and transplant events in the validation cohort (n = 92). CONCLUSION: This study provides a novel classification of AC with distinct genetic backgrounds indicating different potential pathogenesis. Cluster 1 is distinct in genotype and clinicopathology and can be defined as 'desmosomal cardiomyopathy'. Precordial QRS amplitude is an independent indicator reflecting the right ventricular remodelling, which may be able to predict transplant/death events for AC patients.

Recessive variants in plakophilin-2 contributes to early-onset arrhythmogenic cardiomyopathy with severe heart failure.

AIMS: Plakophilin-2 (PKP2) is the most prevalent mutant gene causing arrhythmogenic cardiomyopathy (ACM) and PKP2 carriers are prone to develop ventricular arrhythmic events. The objective of this study is to use integrated analysis of whole genome sequencing (WGS) and transcriptome sequencing (RNAseq) to identify deep intronic and/or coding variants that cause aberrant splicing events in ACM patients, and hence, to test the hypothesis that recessive variants in PKP2 may lead to early-onset ACM with severe heart failure. METHODS AND RESULTS: We performed WGS and RNAseq in 27 heart transplanted ACM patients. By integrated analysis of WGS/RNAseq, we discovered that two patients with PKP2 variants were affected in recessive pattern. One patient had aberrant splicing arising from two intronic variants that led to exon skipping and exon retention. We screened three additional recessive PKP2 variants in 47 non-heart transplanted ACM patients. We compared the clinical characteristics of recessive PKP2 (n = 5) and heterozygous PKP2 carriers (n = 18), and found that recessive PKP2 variant carriers all had early-onset ACM with left ventricular dysfunction. We examined truncating PKP2 variants in explanted hearts and confirmed that truncated PKP2 was not translated. Moreover, the morphology of intercalated disc in recessive PKP2 variants carriers was similar to normal heart suggesting little intercalated disc remodelling. CONCLUSION: By using combined implementation of WGS RNAseq, we were able to demonstrate that recessive variants in PKP2 may contribute to early-onset ACM with severe heart failure. These findings may play a role in risk stratification of ACM based on genetic testing in clinical practice.

Sarcomere variants in arrhythmogenic cardiomyopathy: Pathogenic factor or bystander?

BACKGROUND: Arrhythmogenic cardiomyopathy (ACM) is an inherited heart muscle disease, which is mainly caused by desmosomal mutations. Sarcomere variants were the primary genetic basis of hypertrophic cardiomyopathy (HCM) and were recently detected in arrhythmogenic cardiomyopathy (ACM). Our aim is to seek potential pathogenic variants of sarcomere genes in our ACM cohort and describe their characteristics. METHODS: We performed targeted sequencing of 14 sarcomere genes in 84 patients with ACM and set strict criteria to identify potential pathogenic variants. Clinical screening was performed on all available family members of the patients carrying sarcomere variants and specific variants were tested in screened family members by Sanger sequencing. RESULTS: We identified 6 sarcomere variants in 6 (7%) patients, which were all definite ACM. Sarcomere variants were detected in NEBL, MYH7, MYH6 and TNNI3, with low prevalence in controls and predicted pathogenic in silico. Among these patients, three had previous detected PKP2 variants. Patients with sarcomere variants all experienced major arrhythmic cardiac event (MACE) with the average age of the first documented MACE being 41.2 ±â€¯11.0 years. Pedigrees analysis showed none of the sarcomere variants carriers among the family members were affected, indicating very low penetrance. CONCLUSIONS: We detected some sarcomere variants in our ACM cohort. Although those patients with sarcomere variants had severe arrhythmic burden, family co-segregation analysis didn't strongly support a primary role in the pathogenesis of ACM.

A founder homozygous DSG2 variant in East Asia results in ARVC with full penetrance and heart failure phenotype.

BACKGROUND: Variants in the desmoglein-2 (DSG2) gene account for a significant proportion of patients with Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC). The aim of this study was to evaluate the genetic epidemiology of DSG2 and the impact of a frequent homozygous DSG2 variant in East Asia. METHODS: Genetic screening of 14 ARVC related genes was performed in 118 unrelated index patients using next-generation sequencing. Following that, family screening, clinical evaluation and haplotype analysis were performed among eight probands who carry the same homozygous DSG2 variant. We also examined the histopathology and protein expression using immunofluorescence staining on the myocardial tissue of two probands undergoing heart transplant. RESULTS: Eighteen (15.2%) patients bear rare putatively deleterious variants in DSG2, among which 8 patients shared the homozygous DSG2 p.Phe531Cys variant. Family screening demonstrated that only homozygous variant carriers exhibited definite ARVC phenotype with 100% penetrance, while heterozygous variant carriers were either unaffected or only presented mild ARVC related symptoms in 25% relatives. Left ventricular involvement and bi-ventricular failure were common among homozygous p. Phe531Cys variant patients even at early age. Haplotype analysis demonstrated p. Phe531Cys was a founder variant in East Asia population with an allele frequency of 0.12%. CONCLUSIONS: We identified, for the first time, a homozygous founder variant of DSG2 in East Asia, which was at surprisingly high frequency of 8.47% among Chinese ARVC patients with a full penetrance. This result suggested an urgent demand of genetic counseling for the probands and their relatives with heterozygous variant.

Bcl2-Like Protein 12 Is Required for the Aberrant T Helper-2 Polarization in the Heart by Enhancing Interleukin-4 Expression and Compromising Apoptotic Machinery in CD4+ T Cells.

BACKGROUND: The biased T helper-2 (Th2) response plays a critical role in myocarditis. Bcl2-like protein 12 (Bcl2L12) is associated with the Th2 pattern of inflammation. This study aims to elucidate the role of Bcl2L12 in the pathogenesis of Th2-biased inflammation in the heart. METHODS: Mice were treated with the myosin heavy-chain-α peptides to induce inflammation in the heart. Human hearts were collected from the surgically removed hearts of patients who had undergone heart transplantation. RESULTS: The expression of Bcl2L12 was detected in CD4+ T cells of the hearts, which was markedly higher in the hearts with myocarditis at the advanced stage of heart failure compared with the control (dilated cardiomyopathy) hearts without myocarditis. Mice with Bcl2L12-deficient CD4+ T cells failed to induce the Th2-biased inflammation in the heart. CD4+ T cells with a higher expression of Bcl2L12 were prone to differentiate into Th2 cells. Bcl2L12 formed a complex with GATA3 in CD4+ T cells to enhance the binding between GATA3 and the Il4 promoter, which promoted the Il4 gene transcription. Bcl2L12 compromised the apoptotic machinery by inhibiting the expression of p53 in CD4+ T cells to reduce the activation-induced CD4+ T cell death. CONCLUSIONS: CD4+ T cells isolated from hearts with myocarditis at the end stage of heart failure express high levels of Bcl2L12, and the latter is required for the development of aberrant Th2 polarization in the heart. The Bcl2L12 may be a novel target in the treatment of myocarditis as well as other Th2-biased inflammation.