BACKGROUND:Statistical risk models for durable left ventricular assist device (LVAD) implantation inform candidate selection, quality improvement, and evaluation of provider performance. This study developed a 90-day mortality risk model using The Society of Thoracic Surgeons National Intermacs Database (STS Intermacs). METHODS:STS Intermacs was queried for primary durable LVAD implants from January 2019 to September 2023. Multivariable logistic regression was used to derive a model based on preimplant risk factors by using derivation (2019-2021 implants) and validation (2022-2023 implants) cohorts. Model performance (derivation and validation cohorts) was assessed using C-statistics, Brier scores, and calibration plots. A refined model (all patients) was generated to calculate observed-to-expected (O/E; 95% CI) ratios for each center. RESULTS:The study population consisted of 11,342 patients from 2019 to 2023 who were sequentially divided in time into derivation (n = 6775) and validation (n = 4567) cohorts. Ninety-day mortality was 8.0% (9.2% in the derivation cohort vs 7.4% in the validation cohort; P = .001). Logistic regression applied to derivation and validation cohorts produced similar discrimination (area under the curve [AUC], 0.714 [95% CI, 0.69-0.74]; and AUC, 0.707; [95% CI, 0.67-0.72], respectively) and calibration (Brier score, .08 vs .07), with overestimation of risk among patients with a predicted risk >0.4. The O/E analysis identified 22 (12.5%) centers with worse than expected mortality with a 95% CI >1.0 and 14 centers (8.0%) with better than expected mortality with a 95% CI <1.0 (all P < .05). CONCLUSIONS:The STS Intermacs risk model demonstrated satisfactory discrimination and calibration. This tool may be used to inform candidate selection, facilitate quality improvement, and assess provider performance.

Background: Parkin-mediated mitophagy eliminates dysfunctional mitochondria to reduce inflammatory responses caused by mtDAMPs. Given that reduced mitophagy is a hallmark of aging and AAA is an aging-associated disease, we sought to investigate the role of Parkin-mediated mitophagy in the development of AAAs. Methods: Groups of young (8-10 wks, n= 6/group) and aged (18-20 months, n=6/group) male Mito-QC mice either without intervention or underwent AAV.mPCSK9 D377Y infection and western diet feeding followed by Angiotensin II (AngII) or saline pump infusion for 28 days. Separately, young male Myh11-creER T2 Parkin fl/fl mice underwent tamoxifen (Parkin SMCKO) or vehicle injections (n=35-39/group), AAV.mPCSK9 D377Y infection, western diet feeding and AngII infusion. In vitro , MOVAs were treated with AngII and the USP30 inhibitor, a mitophagy enhancer, or vehicle followed by assessment of Parkin and mtROS. Results: VSMCs in aged Mito-QC mice, identified by a CD45 - CD90 - α-actin + profile, exhibit diminished mitophagy activity (p=0.017) and decreased Parkin expression (p=0.029). In young AAAs, VSMCs characterized as CD45 - CD90 - α-actin high and α-actin low also demonstrated decreased mitophagy (p=0.0017, p=0.0020), decreased Parkin(p=0.029), and a decreased trend in SDHB in Complex II (p=0.103) and NDUFB8 in Complex I (p=0.040) of the electron transport chain. Parkin SMCKO mice demonstrated increased AAA rupture (p=0.038), greater aneurysm size (p=0.044), reduced mtDNA copy numbers (p=0.026) and elevated mtROS compared to their controls. Parkin SMCKO mice demonstrated trends of diminished expression of respiratory complexes (p=0.070) and an exacerbated decrease in the maximal OCR involving both coupled and uncoupled activities of Complex I plus II (p=0.045, 0.028). In vitro experiments demonstrated treatment with the USP30 inhibitor reversed the reduction in mitophagy activity and mtROS increasement induced by AngII in MOVAS. Conclusions: In conclusion, mitophagy activity in aortic VSMCs and Parkin decreased with aging and separately, in AAAs and Parkin SMCKO mice, associated with exacerbation of AAA progression. These studies suggest stabilization of Parkin-dependent mitophagy could represent a novel AAA therapeutic target.

Abdominal aortic aneurysms (AAAs) are a degenerative aortic disease and associated with hallmarks of aging, such as mitophagy. Despite this, the exact associations among mitophagy, aging, and AAA progression remain unknown. In our study, gene expression analysis of human AAA tissue revealed downregulation of mitophagy pathways, mitochondrial structure, and function-related proteins. Human proteomic analyses identified decreased levels of mitophagy mediators PINK1 and Parkin. Aged mice and, separately, a murine AAA model showed reduced mitophagy in aortic vascular smooth muscle cells (VSMCs) and PINK1 and Parkin expression. Parkin knockdown in VSMCs aggravated AAA dilation in murine models, with elevated mitochondrial ROS and impaired mitochondrial function. Importantly, inhibiting USP30, an antagonist of the PINK1/Parkin pathway, increased mitophagy in VSMCs, improved mitochondrial function, and reduced AAA incidence and growth. Our study elucidates a critical mechanism that proposes AAAs as an age-associated disease with altered mitophagy, introducing new potential therapeutic approaches.

Background. There is an increasing awareness that aging of the immune system, or immunosenescence, is a key biological process underlying many of the hallmark diseases of aging and age-related decline broadly. While immunosenescence can be in part due to normal age-related changes in the immune system, emerging evidence posits that viral infections may be biological stressors of the immune system that accelerate the pace of immunosenescence Methods. We used a convenience sample of 42 individuals aged 65 years and older to examine correlations between antiviral immunoglobulin G (IgG) levels for 4 human herpesviruses (cytomegalovirus [CMV], herpes simplex virus [types 1 and 2], and Epstein-Barr virus) and multiple indicators of T-cell immunosenescence. Results. We found that most of the sample (n = 33) was antiviral IgG positive for 2 or more of the 4 herpesvirus infections. We also examined correlations between both the total number of viruses for which an individual had antiviral IgG and each individual virus and multiple indicators of T-cell immunosenescence, particularly p16 expression. The strongest correlations were observed between the total number of viruses for which an individual had detectable antiviral IgG and p16 mean fluorescent intensity (MFI) among CD27-CD28-CD57+ CD4+ cells (r = 0.60; P < .001) and between anti-CMV IgG and p16 MFI of CD27-CD57+ CD4+ cells (r = 0.59; P < .001). Conclusions. Broadly, our findings offer compelling preliminary evidence for future investigations to incorporate multiple indicators of persistent viral infections and a more comprehensive set of markers of T-cell immunosenescence in population-based studies of aging.

As there is no assay to predict the risk of acute cellular allograft rejection (ACAR), clinicians rely on graft biopsy and aggressive, one-size-fits-all immunosuppression. Endomyocardial biopsy (EMB) is a flawed standard for heart transplant surveillance and diagnosing ACAR, as histological evidence of rejection inherently lags behind molecular biomarkers and suffers from variability. Noninvasive alternatives to EMB in ACAR surveillance, including gene profiling and donor-derived cell-free DNA, also measure lagging indicators of ACAR. A minimally invasive surveillance method is urgently needed to quantify early risk of rejection for minimizing biopsy and personalizing immunosuppression. We have developed porous biomaterial “scaffolds” for minimally-invasive sampling. These scaffolds amass immune cells producing biomarkers as an immunological niche. We identified predictive biomarkers of ACAR conserved in both in murine heterotopic heart transplant and skin transplant through the remote scaffold. We identified 43 highly differentially-expressed genes as organ-agnostic biomarkers of T cell-mediated rejection. These novel biomarkers differentiate between pre-symptomatic ACAR and recipients with healthy allografts, without invasive biopsy. Scaffold cell capture technology provides a leading indicator of ACAR by monitoring tissue-specific immune responses associated with allograft rejection. This implantable scaffold enables minimally invasive histological evaluation and molecular calculation of the early risk of rejection to reduce the frequency of routine EMB and personalize immune suppression that could prolong transplant life while minimizing risk. Supported by the Falk Medical Research Trust Catalyst Award and Transformational Award

Summary Aging impairs the immune responses to influenza A virus (IAV), resulting in increased mortality to IAV infections in older adults. With aging, there is reduced number and impaired function of alveolar macrophages (AMs), cells critical for defense against IAV. However, factors within the aged lung that impair AMs are not fully known. Using a murine model of IAV infection, we observed that aging increased the level of prostaglandin E 2 (PGE 2 ) in the bronchoalveolar lavage fluid (BALF) of aged mice compared to young mice. Blockade of the PGE 2 receptor EP2 in aged mice increased AM numbers and subsequently enhanced survival to IAV. Additionally, PGE 2 impaired the mitochondrial health of AMs. We also identified senescent type II alveolar epithelial cells (AECs) as a source of the aged-associated PGE 2 in the lung. Our results reveal a crosstalk between AECs and AMs, via PGE 2 , that compromises host defense to IAV infection with aging.

Abstract A novel population of age-associated Granzyme K (GZMK)-expressing CD8 T cells was found in mice and humans. These cells enhance local tissue senescence and inflammation and are distinct from central memory and conventional Granzyme B- or Interferon γ-producing effector memory CD8 T cells. It is unknown whether these cells drive chronic disease; thus, we induced atherosclerosis in young (3-mo) and aged (18-mo) wild-type mice via the PCSK9-AAV model and used scRNAseq to demonstrate that this GZMK-CD8 T cell population homes to atherosclerotic lesions exclusively in aged mice. Neutralizing CD8 T cells demonstrates that GZMK-CD8 cells drive age-enhance atherosclerosis. Finally, we transferred GZMK-CD8 cells from different aged donors into young CD8-/- hosts and demonstrate that GZMK-CD8 cells from aged but not young donors drive atherosclerosis. In conclusion, we identified a novel role for this recently described population of aging-specific GZMK-expressing CD8+ T cells as a critical driver of chronic disease.

Older people exhibit dysregulated innate immunity to respiratory viral infections, including influenza and SARS-CoV-2, and show an increase in morbidity and mortality. Nanoparticles are a potential practical therapeutic that could reduce exaggerated innate immune responses within the lungs during viral infection. However, such therapeutics have not been examined for effectiveness during respiratory viral infection, particular in aged hosts. Here, we employed a lethal model of influenza viral infection in vulnerable aged mice to examine the ability of biodegradable, cargo-free nanoparticles, designated ONP-302, to resolve innate immune dysfunction and improve outcomes during infection. We administered ONP-302 via i.v. injection to aged mice at day 3 after infection, when the hyperinflammatory innate immune response was already established. During infection, we found that ONP-302 treatment reduced the numbers of inflammatory monocytes within the lungs and increased their number in both the liver and spleen, without impacting viral clearance. Importantly, cargo-free nanoparticles reduced lung damage, reduced histological lung inflammation, and improved gas exchange and, ultimately, the clinical outcomes in influenza-infected aged mice. In conclusion, ONP-302 improves outcomes in influenza-infected aged mice. Thus, our study provides information concerning a practical therapeutic, which, if translated clinically, could improve disease outcomes for vulnerable older patients suffering from respiratory viral infections.

Purpose As there is no assay to predict the risk of acute cellular allograft rejection (ACAR), clinicians rely on protocol graft biopsy and aggressive, one-size-fits-all immunosuppression. Immunosuppression protects grafts from ACAR but increases systemic toxicities. Endomyocardial biopsy (EMB) histology suffers from variability and lags behind molecular biomarkers. A minimally invasive surveillance method is urgently needed to quantify early risk of rejection for minimizing graft biopsy and personalizing treatment. Methods Biomaterial scaffolds accumulate immune cells producing biomarkers of ACAR as an engineered immunological niche. We implanted subcutaneous poly-caprolactone scaffolds in murine heart or skin transplants to determine if they could identify ACAR. Rag2KO mice received full MHC mismatch allografts or syngeneic controls, and ACAR was initiated as a tunable event by C57BL/6 T cell transfer. Scaffolds were explanted and analyzed via histology and differential gene expression by RNA sequencing. Results The scaffolds provided a novel measure of graft health. We algorithmically identified 11 differentially-expressed genes as biomarkers that distinguish mice with rejecting grafts from those with healthy grafts. Importantly, the scoring system detects oncoming ACAR prior to clinical signs of rejection. Also, histology of these niches identified changes associated with ACAR progression. Conclusion Gene expression in the cell-capture scaffold identified a biomarker signature of early ACAR, without invasive biopsy. Scaffold cell capture technology provides a leading indicator of ACAR by monitoring tissue-specific immune responses associated with allograft rejection. This implantable scaffold enables minimally invasive histological evaluation and molecular calculation of the early risk of rejection to reduce the frequency of routine EMB and personalize immune suppression that ultimately could prolong transplant life while minimizing risk.

Rationale: Aging is a strong risk factor for atrial fibrillation (AF), the most common sustained arrhythmia in the clinical practice. Atrial inflammation correlates with increased AF susceptibility but whether chronic age-related inflammation that occurs with atherosclerosis contributes to AF is unknown. Hypothesis: Hematopoietic factors contribute to AF inducibility in aged atherosclerotic mice. Methods: We used burst electrical stimulation (tachypacing) of the right atrium to test susceptibility to AF in-vivo in young and aged atherosclerotic, low density lipoprotein receptor knockout (C57BL/6 Ldlr -/- ) mice, and young and old wildtype (C57BL/6 WT) mice. We also determined the role of the stroma vs. the hematopoietic system, by creating bone marrow chimeras in which aged or young Ldlr -/- mice were transplanted with age-matched or mismatched bone Ldlr -/- bone marrow. We used whole-cell patch-clamping investigate atrial sodium currents. Confocal microscopy and patch-clamping in current clamp mode was used to simultaneously record action potentials and Ca 2+ transients. Results: Upon atrial tachypacing, aged atherosclerotic mice underwent longer and more frequent AF episodes than young (incidence, 0.47±0.09 vs 0.12±0.02 episodes/attempts; p<0.05 ) and aged WT mice (0.47±0.09 vs 0.16±0.07 episodes/attempts; p<0.05 ). Importantly, young-to-old bone marrow chimeric mice exhibited reduced AF incidence (0.23 ± 0.05 episodes/attempts), whereas old-to-young chimeric mice exhibited increased AF incidence (0.45 ± 0.08 episodes/attempts). Atrial myocytes from aged atherosclerotic mice presented a 50% reduction in the cardiac inward sodium current (I Na ). Moreover, compared to young, aged atherosclerotic mice showed prolonged action potential duration (APD90: 34.0±5.0 ms vs 48.1±7.0ms; p<0.05), post-pacing spontaneous calcium releases (25% vs 81.8%; p<0.05) and triggered activity (0% vs 27.2 %; p<0.05). Conclusions: Aged atherosclerotic prone mice are susceptible to AF induction. Hematopoietic factors are sufficient to increase AF propensity with aging in the atherosclerotic host possibly by causing electrophysiological remodeling and intracellular Ca 2+ handling abnormalities.

Introduction: How aging impacts humoral immunity to organ transplantation is unclear. Here, we investigated B cell responses to organ transplantation by employing an experimental murine model. Methods:i) Skin transplant model in which young (2-3 months) and aged (16-18 months) C57BL/6 mice were transplanted with an allogenic skin (young) BALB/c graft. Recipients were either not treated (NT) or received, perioperative anti-CD45RB + anti-CD154. ii) Flow cytometric anaylsis of spleens for B cell phenotyping. iii) ELISA to measure circulating antibodies. Results: Aged recipients exhibited a faster time to allograft rejection than young transplant recipients administered immune therapy (Figure 1A). In young recipients, immunotherapy depleted absolute numbers of follicular (FO), marginal zone (MZ) and immature splenic B cells. Although immunotherapy in aged recipients resulted in depletion of splenic FO and MZ B cells, absolute numbers and frequency of splenic immature B cell remained unchanged in contrast to young recipients (Figure 1B). Characterization of splenic B cells revealed that aged immature B cells had higher expression of MHC-II, TLR2, CD80, and CD86 compared to young immature B cells, indicating that these cells exhibit an activated phenotype with aging. In addition, aged mice had greater levels of circulating total IgM and IgG at baseline and 7-days post skin transplantation compared to young mice.Figure: No Caption available.Conclusions: Aging impairs the efficacy of immune therapy to extend allograft survival. In particular, with aging immature B cells resist immune depletion and exhibit an activated phenotype. Hence, we have potentially uncovered a novel age-specific pathway which enhances humoral immunity to impair immune regulation and accelerate allograft rejection.

Introduction Inflammation is detrimental after organ transplantation, yet the identity of inflammatory mediators after transplantation is largely unknown. Here, we applied a non-biased strategy to discover novel inflammatory mediators after heart transplantation. Methods We employed the following:i) a murine heterotopic heart transplant model to measure intra-graft inflammatory cytokines/chemokines (ELISA); ii) an in vitro assay in which lysates of cardiac transplants are cultured with dendritic cells (DCs) and cytokines measured in supernatants (ELISA); iii) mass spectrometry of non-transplanted and transplanted heart proteomes; iv) immunohistochemical staining of human endomyocardial biopsies. Results At 24 h after transplantation in mice, intra-graft levels of IL-12p40, TNFα, and MIP1α were elevated with similar levels between allografts and syngeneic grafts. Cardiac transplantation enhanced DC inflammatory responses, which were dependent on proteins (determined via enzymatic digestion). Subsequent proteomics discovered that several proteins were upregulated at 24h post transplantation including those involved in cytoskeletal function, cell adhesion and immune response. Haptoglobin (Hp) was one of the most upregulated proteins and we independently validated its upregulation via ELISA. Genetic deficiency of Hp diminished intra-graft levels of IL-12p40, TNFα, and MIP1α (p<0.01) and increased the ability of CTL4A Ig to enhance murine cardiac allograft survival (Figure A). Finally, intra-graft expression of Hp correlated with acute graft rejection in human heart transplant specimens as compared with heart transplant samples without acute rejection (Figure B).Figure: No Caption available.Conclusion Our proteomic screen has identified intra-graft haptoglobin as a novel enhancer of cardiac transplant rejection.

s S97 serum-containing culture medium. In group B, instead of the 3D heart model, a spheric glas spacer (diameter 10mm) was used to construct pouch like BioVADs. Results: The engineered tissue beat spontaneously and showed contractile properties of native heart muscle including positive inotropic responses to calcium and isoprenaline. In group A recipient heart matched BioVADs were implanted into the corresponding healthy rats (n= 10), while in group B the spheric BioVADs were implanted (n= 10). 14 days after implantation hearts were explanted for histology. Histological analysis of recipient-matched BioVADs showed excellent coverage of the epicardial heart surface, while spheric BioVADs showed high number of micro and macro gaps. Furthermore direct alignment of the BioVADs and recipients hearts was measured in cross-sectioned histological compounds. In group B, a statistically higher number of areas with loss of contact between BioVADs and recipient hearts was seen compared to group A. Conclusion: We developed a novel casting technology using small animal MRI and 3D printing to generate artificial cardiac tissue that is perfectly matched to the recipient heart and exhibits structural and functional properties of native myocardium.

AbstractElevated levels of COX-derived prostaglandin E2 (PGE2) occur in inflamed tissues. To evaluate the potential links between inflammation and breast cancer, levels of urinary prostaglandin E metabolite (PGE-M), a stable end metabolite of PGE2, were quantified. We enrolled 400 patients with breast cancer: controls with early breast cancer (n = 200), lung metastases (n = 100), and metastases to other sites (n = 100). Patients completed a questionnaire, provided urine, and had measurements of height and weight. Urinary PGE-M was quantified by mass spectrometry. Ever smokers with lung metastasis who had not been exposed to nonsteroidal anti-inflammatory drugs (NSAIDs) had the highest PGE-M levels. PGE-M levels were increased in association with elevated body mass index (BMI; P < 0.001), aging (P < 0.001), pack-year smoking history (P = 0.02), lung metastases (P = 0.02), and recent cytotoxic chemotherapy (P = 0.03). Conversely, use of NSAIDs, prototypic inhibitors of COX activity, was associated with reduced PGE-M levels (P < 0.001). On the basis of the current findings, PGE-M is likely to be a useful biomarker for the selection of high-risk subgroups to determine the use of interventions that aim to reduce inflammation and possibly the development and progression of breast cancer, especially in overweight and obese women. Cancer Prev Res; 6(5); 428–36. ©2013 AACR.