Keeping immune checkpoint inhibitor myocarditis in check: advanced circulatory mechanical support as a bridge to recovery

Immune checkpoint inhibitor (ICI)‐associated myocarditis is a rare, potentially life‐threatening complication of immunotherapy. We report a case of a 60‐year‐old female with a history of colorectal cancer treated with nivolumab immunotherapy who presented with new cardiomyopathy complicated by cardiogenic shock and ventricular arrhythmias. Treatment of ICI‐associated myocarditis requires aggressive immunosuppression and supportive therapy. In this case, the patient required advanced mechanical circulatory support as a bridge to recovery. This case highlights the complexity of diagnosis, haemodynamic management, and treatment of fulminant ICI myocarditis.

Discovery of non-HLA antibodies associated with cardiac allograft rejection and development and validation of a non-HLA antigen multiplex panel: From bench to bedside

We analyzed humoral immune responses to nonhuman leukocyte antigen (HLA) after cardiac transplantation to identify antibodies associated with allograft rejection. Protein microarray identified 366 non-HLA antibodies (>1.5 fold, P < .5) from a discovery cohort of HLA antibody-negative, endothelial cell crossmatch-positive sera obtained from 12 cardiac allograft recipients at the time of biopsy-proven rejection. From these, 19 plasma membrane proteins and 10 autoantigens identified from gene ontology analysis were combined with 48 proteins identified through literature search to generate a multiplex bead array. Longitudinal sera from a multicenter cohort of adult cardiac allograft recipients (samples: n = 477 no rejection; n = 69 rejection) identified 18 non-HLA antibodies associated with rejection (P < .1) including 4 newly identified non-HLA antigenic targets (DEXI, EMCN, LPHN1, and SSB). CART analysis showed 5/18 non-HLA antibodies distinguished rejection vs nonrejection. Antibodies to 4/18 non-HLA antigens synergize with HLA donor-specific antibodies and significantly increase the odds of rejection (P < .1). The non-HLA panel was validated using an independent adult cardiac transplant cohort (n = 21 no rejection; n = 42 rejection, >1R) with an area under the curve of 0.87 (P < .05) with 92.86% sensitivity and 66.67% specificity. We conclude that multiplex bead array assessment of non-HLA antibodies identifies cardiac transplant recipients at risk of rejection.

Heart transplantation in the early phase of the COVID-19 pandemic: A single-center case series

The infectious disease coronavirus disease 2019 (COVID‐19) was declared a pandemic by the World Health Organization in March 2020. The impact of COVID‐19 on solid organ transplantations, including heart transplantation, is currently unclear. Many transplant programs have been forced to swiftly re‐evaluate and adapt their practices, leading to a marked decrease in transplants performed. This trend has been due to various factors, including increased donor COVID‐19 screening scrutiny and recipient waiting list management in anticipation of COVID‐19 critical care surge capacity planning. In the face of these unknown variables, determining when and how to proceed with transplantation in our population of patients with end‐stage cardiomyopathies is challenging. Here, we describe our center's experience with orthotopic heart transplantation (OHT) in one of the country's pandemic epicenters, where we performed eight OHTs in the first 2 months after community spread began in late February 2020.

Clinical phenomapping and outcomes after heart transplantation

BACKGROUND

Survival after heart transplantation (HTx) is limited by complications related to alloreactivity, immune suppression, and adverse effects of pharmacologic therapies. We hypothesize that time-dependent phenomapping of clinical and molecular data sets is a valuable approach to clinical assessments and guiding medical management to improve outcomes.

METHODS

We analyzed clinical, therapeutic, biomarker, and outcome data from 94 adult HTx patients and 1,557 clinical encounters performed between January 2010 and April 2013. Multivariate analyses were used to evaluate the association between immunosuppression therapy, biomarkers, and the combined clinical end point of death, allograft loss, retransplantation, and rejection. Data were analyzed by K-means clustering (K = 2) to identify patterns of similar combined immunosuppression management, and percentile slopes were computed to examine the changes in dosages over time. Findings were correlated with clinical parameters, human leucocyte antigen antibody titers, and peripheral blood mononuclear cell gene expression of the AlloMap (CareDx, Inc., Brisbane, CA) test genes. An intragraft, heart tissue gene coexpression network analysis was performed.

RESULTS

Unsupervised cluster analysis of immunosuppressive therapies identified 2 groups, 1 characterized by a steeper immunosuppression minimization, associated with a higher likelihood for the combined end point, and the other by a less pronounced change. A time-dependent phenomap suggested that patients in the group with higher event rates had increased human leukocyte antigen class I and II antibody titers, higher expression of the FLT3 AlloMap gene, and lower expression of the MARCH8 and WDR40A AlloMap genes. Intramyocardial biomarker-related coexpression network analysis of the FLT3 gene showed an immune system-related network underlying this biomarker.

CONCLUSIONS

Time-dependent precision phenotyping is a mechanistically insightful, data-driven approach to characterize patterns of clinical care and identify ways to improve clinical management and outcomes.

Emerging pharmacologic and structural therapies for hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy is the most common inherited heart disease. Although it was first described over 50 years ago, there has been little in the way of novel disease-specific therapeutic development for these patients. Current treatment practice largely aims at symptomatic control using old drugs made for other diseases and does little to modify the disease course. Septal reduction by surgical myectomy or percutaneous alcohol septal ablation are well-established treatments for pharmacologic-refractory left ventricular outflow tract obstruction in hypertrophic cardiomyopathy patients. In recent years, there has been a relative surge in the development of innovative therapeutics, which aim to target the complex molecular pathophysiology and resulting hemodynamics that underlie hypertrophic cardiomyopathy. Herein, we review the new and emerging therapeutics for hypertrophic cardiomyopathy, which include pharmacologic attenuation of sarcomeric calcium sensitivity, allosteric inhibition of cardiac myosin, myocardial metabolic modulation, and renin-angiotensin-aldosterone system inhibition, as well as structural intervention by percutaneous mitral valve plication and endocardial radiofrequency ablation of septal hypertrophy. In conclusion, while further development of these therapeutic strategies is ongoing, they each mark a significant and promising advancement in treatment for hypertrophic cardiomyopathy patients.

Cardiac Amyloidosis: Diagnosis and Treatment Strategies

Cardiac amyloidosis in the United States is most often due to myocardial infiltration by immunoglobulin protein, such as in AL amyloidosis, or by the protein transthyretin, such as in hereditary and senile amyloidosis. Cardiac amyloidosis often portends a poor prognosis especially in patients with systemic AL amyloidosis. Despite better understanding of the pathophysiology of amyloid, many patients are still diagnosed late in the disease course. This review investigates the current understanding and new research on the diagnosis and treatment strategies in patients with cardiac amyloidosis. Myocardial amyloid infiltration distribution occurs in a variety of patterns. Structural and functional changes on echocardiography can suggest presence of amyloid, but CMR and nuclear imaging provide important complementary information on amyloid burden and the amyloid subtype, respectively. While for AL amyloid, treatment success largely depends on early diagnosis, for ATTR amyloid, new investigational agents that reduce production of transthyretin protein may have significant impact on clinical outcomes. Advancements in the non-invasive diagnostic detection and improvements in early disease recognition will undoubtedly facilitate a larger proportion of patients to receive early therapy when it is most effective.

Heart Failure Therapies for End-Stage Chemotherapy-Induced Cardiomyopathy

With ongoing advancements in cancer-related treatments, the number of cancer survivors continues to grow globally, with numbers in the United States predicted to reach 18 million by 2020. As a result, it is expected that a greater number of patients will present with chemotherapy-related side effects. One entity in particular, chemotherapy-related cardiomyopathy (CCMP), is a known cardiotoxic manifestation associated with agents such as anthracyclines, trastuzumab, and tyrosine kinase inhibitors. Although such effects have been described in the medical literature for decades, concrete strategies for screening, prevention, and management of CCMP continue to be elusive owing to limited studies. Late recognition of CCMP is associated with a poorer prognosis, including a lack of clinical response to pharmacologic therapy, and end-stage heart failure. A number of advanced cardiac therapies, including cardiac resynchronization therapy, ventricular assist devices, and orthotopic cardiac transplantation, are available to for end-stage heart failure; however, the role of these therapies in CCMP is unclear. In this review, management of end-stage CCMP with the use of advanced therapies and their respective effectiveness are discussed, as well as clinical characteristics of patients undergoing these treatments. The relative paucity of data in this field highlights the importance and need for larger-scale longitudinal studies and long-term registries tracking the outcomes of cancer survivors who have received cardiotoxic cancer therapy to determine the overall incidence of end-stage CCMP, as well as prognostic factors that will ultimately guide such patients toward receiving appropriate end-stage care.

Free Fatty Acid Impairment of Nitric Oxide Production in Endothelial Cells Is Mediated by IKKβ

Objective— Free fatty acids (FFA) are commonly elevated in diabetes and obesity and have been shown to impair nitric oxide (NO) production by endothelial cells. However, the signaling pathways responsible for FFA impairment of NO production in endothelial cells have not been characterized. Insulin receptor substrate-1 (IRS-1) regulation is critical for activation of endothelial nitric oxide synthase (eNOS) in response to stimulation by insulin or fluid shear stress.

Methods and Results— We demonstrate that insulin-mediated tyrosine phosphorylation of IRS-1 and serine phosphorylation of Akt, eNOS, and NO production are significantly inhibited by treatment of bovine aortic endothelial cells with 100 μmol/L FFA composed of palmitic acid for 3 hours before stimulation with 100 nM insulin. This FFA preparation also increases, in a dose-dependent manner, IKKβ activity, which regulates activation of NF- κB, a transcriptional factor associated with inflammation. Similarly, elevation of other common FFA such as oleic and linoleic acid also induce IKKβ activation and inhibit insulin-mediated eNOS activation. Overexpression of a kinase inactive form of IKKβ blocks the ability of FFA to inhibit insulin-dependent NO production, whereas overexpression of wild-type IKKβ recapitulates the effect of FFA on insulin-dependent NO production.

Conclusions— Elevated levels of common FFA found in human serum activate IKKβ in endothelial cells leading to reduced NO production, and thus may serve to link pathways involved in inflammation and endothelial dysfunction.

Purification and identification of secreted oxidative stress-induced factors from vascular smooth muscle cells

Reactive oxygen species have been implicated in the pathogenesis of atherosclerosis and hypertension, in part by promoting vascular smooth muscle cell (VSMC) growth. We have previously shown that LY83583, a generator of O-(2), activated extracellular signal-regulated kinases (ERK1/2) with early (10 min) and late (2 h) peaks and stimulated VSMC growth. To investigate whether secreted oxidative stress-induced factors (termed SOXF) from VSMC were responsible for late ERK1/2 activation in response to LY83583, we purified putative SOXF proteins from conditioned medium (2 h of LY83583 exposure) by sequential chromatography based on activation of ERK1/2. Proteins identified by capillary chromatography, electrospray ionization tandem mass spectrometry, and data base searching included heat shock protein 90-alpha (HSP90-alpha) and cyclophilin B. Western blot analysis of conditioned medium showed specific secretion of HSP90-alpha but not HSP90-beta. Immunodepletion of HSP90-alpha from conditioned medium significantly inhibited conditioned medium-induced ERK1/2 activation. Human recombinant HSP90-alpha reproduced the effect of conditioned medium on ERK1/2 activation. These results show that brief oxidative stress causes sustained release of protein factors from VSMC that can stimulate ERK1/2. These factors may be important mediators for the effects of reactive oxygen species on vascular function.

Differential activation of mitogen-activated protein kinases by H2O2 and O2- in vascular smooth muscle cells

Increased generation of active oxygen species such as H2O2 and O2- may be important in vascular smooth muscle cell growth associated with atherosclerosis and restenosis. In previous work, we showed that H2O2 stimulated vascular smooth muscle cell growth and proto-oncogene expression. In the present study, we compared the effects of H2O2 and O2- on cultured rat aortic vascular smooth muscle cell growth and signal transduction. O2- was generated in a concentration-dependent manner by the naphthoquinolinedione LY83583. Vascular smooth muscle cell growth, as measured by [3H]thymidine incorporation, was stimulated by 200 mumol/L H2O2 (110% increase versus 0.1% serum) and 1 mumol/L LY83583 (175% increase) to levels comparable to 10 ng/mL platelet-derived growth factor (210% increase). Since activation of mitogen-activated protein kinase (MAP kinase) is one of the earliest growth factor signal events, the activity of MAP kinase was measured by changes in mobility on Western blot and by phosphorylation of myelin basic protein. There was a concentration-dependent increase in MAP kinase activity by LY83583 (maximum, 10 mumol/L) but not by H2O2. The time course for activation of MAP kinase by LY83583 showed a maximum at 5 to 10 minutes with return to baseline by 20 minutes. Activation of MAP kinase by LY83583 was protein kinase C dependent. Expression of MAP kinase phosphatase-1 (MKP-1), a transcriptionally regulated redox-sensitive protein tyrosine/threonine phosphatase, was also measured. Although H2O2 induced MKP-1 mRNA to a greater extent than did LY83583, the increased MKP-1 expression could not explain the inability of H2O2 to stimulate MAP kinase, because mRNA levels were not detected until 60 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)

Activation of mitogen-activated protein kinases by arachidonic acid and its metabolites in vascular smooth muscle cells

Previous studies from this laboratory and others suggest that arachidonic acid and its metabolites play important roles in a variety of biological processes such as signal transduction, contraction, chemotaxis, and cell growth and differentiation. Here we studied the effect of arachidonic acid on mitogen-activated protein (MAP) kinases in vascular smooth muscle cells (VSMC). Arachidonic acid activated MAP kinases in VSMC in a time- and dose-dependent manner. Nordihydroguaiaretic acid (NDGA), a potent inhibitor of the lipoxygenase system, significantly blocked the arachidonic acid-induced activation of MAP kinases, whereas indomethacin, an inhibitor of cyclooxygenase, had no effect. In VSMC, arachidonic acid was converted to 15-hydroxyeicosatetraenoic acid (15-HETE); NDGA inhibited the formation of this HETE. Exogenous addition of 15-HETE to VSMC caused stimulation of MAP kinases. Depletion of protein kinase C attenuated both the arachidonic acid- and 15-HETE-induced activation of MAP kinases in VSMC. Together these results suggest that 1) arachidonic acid activates MAP kinases in VSMC; 2) 15-HETE, a 15-lipoxygenase product of arachidonic acid, at least in part, mediates the arachidonic acid effect on MAP kinases; and 3) protein kinase C appears to be important in arachidonic acid activation of MAP kinases. Therefore, MAP kinases may play an important role in arachidonic acid signaling of VSMC growth and function.