Thomas J. Dengler

Inhibition of IL-17A Attenuates Atherosclerotic Lesion Development in ApoE-Deficient Mice

The importance of an (auto)immune response in atherogenesis is becoming increasingly well understood. IL-17A-expressing T cells modulate immune cell trafficking, initiating inflammation and cytokine production in (auto)immune diseases. In human carotid artery plaques, we previously showed the presence of IL-17A-producing T cells and IL-23; however, IL-17A effects on atherogenesis have not been studied. Aortic root sections from 8-wk-old apolipoprotein E-deficient mice fed a standard chow diet were examined after 12 wk for lesion area, plaque composition, cellular infiltration, cytokine expression, and apoptosis. The treatment group (n = 15) received anti-IL-17A Ab and the controls (n = 10) received irrelevant Abs. Inhibition of IL-17A markedly reduced atherosclerotic lesion area (p < 0.001), maximal stenosis (p < 0.001), and vulnerability of the lesion. IL-17A mAb-treated mice showed reduced cellular infiltration, down-regulation of activation markers on endothelium and immune cells (e.g., VCAM-1), and reduced cytokine/chemokine secretion (e.g., IL6, TNFα, CCL5). To investigate possible mechanisms, different atherogenic cell types (e.g., macrophages, dendritic cells, HUVECs, vascular smooth muscle cells) were stimulated with IL-17A in addition to TNF-α, IFN-γ, or LPS to induce cellular activation or apoptosis in vitro. Stimulation with IL-17A induced proinflammatory changes in several atherogenic cell types and apoptotic cell death in murine cells. Functional blockade of IL-17A reduces atherosclerotic lesion development and decreases plaque vulnerability, cellular infiltration, and tissue activation in apolipoprotein E-deficient mice. The present data support a pathogenic role of IL-17A in the development of atherosclerosis by way of its widespread proinflammatory and proapoptotic effects on atherogenic cells.

Impaired ventilatory efficiency in chronic heart failure: Possible role of pulmonary vasoconstriction

BACKGROUND Patients with chronic heart failure show impairment of ventilatory efficiency, defined as the relation between ventilation and carbon dioxide output. It is caused by ventilation of excess physiologic dead space. We hypothesized a role of active vasoconstriction in the increase of physiologic dead space, presumed to lead to alveolar hypoperfusion. METHODS AND RESULTS In 57 patients with chronic heart failure (New York Heart Association classification II through IV, ejection fraction 25.6%+/-10.4%) and 7 control subjects, gas exchange at rest and on exercise was compared with hemodynamic measurements and, in a subgroup of 15 patients, with endothelin-1, epinephrine, and norepinephrine levels in the pulmonary and systemic circulation. Ventilatory efficiency at rest (VE/VCO2 ratio) correlated with ventilatory efficiency on exercise (VE vs VCO2 slope). Impairment of ventilatory efficiency correlated strongly negative with exercise tolerance (maximal oxygen uptake: r = -0.67) and cardiac output (r = -0.66) and positive with pulmonary hypertension (mean pulmonary artery pressure: r = 0.69, pulmonary vascular resistance: r = 0.60). None of the vasoconstrictors correlated with reduction of ventilatory efficiency in the subgroup studied. CONCLUSIONS Impairment of ventilatory efficiency in chronic heart failure is correlated with resting pulmonary artery pressures and associated with the impairment of exercise capacity. An imbalance of pulmonary vascular tone probably leads to both pulmonary hypertension and alveolar hypoperfusion.

Troponin T concentrations 72 hours after myocardial infarction as a serological estimate of infarct size

Background: After acute myocardial infarction, the structural protein T is released considerably longer than cytosolic creatine kinase (CK), CK MB isoenzyme (CK-MB), or lactate dehydrogenase (LDH) and late troponin T release (> 48 hours after onset of chest pain) appears to be less affected by early coronary reperfusion. Objective: To investigate the precision of a single measurement of circulating troponin T concentrations 72 hours after onset of chest pain compared with standard scintigraphic and enzymatic estimates of myocardial infarct size. Methods: Quantitative single photon emission computed tomography thallium-201 scintigraphy at rest was performed in 37 patients 2–3 weeks after myocardial infarction (group 1: 14 patients without early coronary reperfusion; group 2: 23 patients with early reperfusion achieved by thrombolytic therapy, by percutaneous transluminal coronary angioplasty, or by both). Results: In both groups, the number of myocardial segments with abnormal thallium-201 uptake indicating the individual extent of irreversible myocardial damage correlated significantly with the troponin T concentrations 72 hours after infarction as well as with peak concentrations of CK, CK-MB, and LDH. Conclusion: The data show that a single measurement of circulating troponin T 72 hours after onset of chest pain—independent of reperfusion—is superior for the estimation of myocardial infarct size to measurement of peak CK, CK-MB, or LDH, which require serial determinations and depend on coronary reperfusion.

Prophylactic implantation of cardioverter-defibrillator in patients with severe cardiac amyloidosis and high risk for sudden cardiac death

BACKGROUND Cardiac light-chain amyloidosis carries a high risk for death predominantly from progressive cardiomyopathy or sudden death (SCD). Independent risk factors for SCD are syncope and complex nonsustained ventricular arrhythmias. OBJECTIVE The purpose of this study was to test whether prophylactic placement of an implantable cardioverter-defibrillator (ICD) reduces SCD in patients with cardiac amyloidosis. METHODS Nineteen patients with histologically proven cardiac amyloidosis and a history of syncope and/or ventricular extra beats (Lown grade IVa or higher) received an ICD. RESULTS During a mean follow-up of 811 +/- 151 days, two patients with sustained ventricular tachyarrhythmias were successfully treated by the ICD. Two patients underwent heart transplantation, and seven patients died due to electromechanical dissociation (n = 6) or glioblastoma (n = 1). Nonsurvivors more often showed progression of left ventricular wall thickness, low-voltage pattern, ventricular arrhythmias (Lown grade IVa or higher), and higher N-terminal pro-brain natriuretic peptide levels than did survivors. Bradycardias requiring ventricular pacing (VVI 40/min <1%, DDD 60/min 6% +/- 1%) occurred only rarely. CONCLUSION Patients with cardiac amyloidosis predominantly die as a result of electromechanical dissociation and other diagnoses not amenable to ICD therapy. Selected patients with cardiac amyloidosis may benefit from ICD placement. Better predictors of arrhythmia-associated SCD and randomized trials are required to elucidate the impact of ICD placement in high-risk patients with cardiac amyloidosis.

Critical Role for Monocyte Chemoattractant Protein-1 and Macrophage Inflammatory Protein-1α in Induction of Experimental Autoimmune Myocarditis and Effective Anti–Monocyte Chemoattractant Protein-1 Gene Therapy

Background— Autoimmune myocarditis is a principal cause of heart failure among young adults and is often a precursor of dilated cardiomyopathy. Monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1α (MIP-1α) are potent chemotactic factors for mononuclear cells. The inflammatory infiltrate observed in myocardial lesions of myocarditis consists of >70% mononuclear cells. To determine their critical role in the pathogenesis of myocarditis, we inhibited mononuclear cell activation and migration to see if it would affect disease severity and disease prevalence in experimental autoimmune myocarditis (EAM). Methods and Results— In this report, we demonstrated that blockade of MCP-1 or MIP-1α with monoclonal antibodies significantly reduced severity of myocarditis in BALB/c mice immunized with cardiac myosin. Similar results were obtained when CCR2−/− and CCR5−/− mice were used. In CCR2−/− mice, not only disease severity but also disease prevalence was reduced. To further inhibit mononuclear cell activation and migration, we transfected the mice before inducing EAM with a dominant-negative inhibitor of MCP-1 gene (7ND). This transfection significantly reduced the disease severity, decreased mRNA expression levels, especially of the chemokines RANTES, MIP-2, IP-10, MCP-1, T-cell activation gene 3, and eotaxin in the myocardium, and resulted in a reduction in cardiac myosin-induced interleukin-1 and interleukin-4 and in an increase in interferon-γ and interleukin-10 cytokine production by splenocytes. Conclusions— Overall, these findings suggest that the chemokines MCP-1 and MIP-1α, acting through their receptors CCR2 and CCR5, are important in the induction of EAM and that inhibition of MCP-1 with 7ND gene transfection significantly reduced disease severity. This strategy may be a new feasible form of gene therapy against autoimmune myocarditis.

Differential immune response to influenza and pneumococcal vaccination in immunosuppressed patients after heart transplantation

INTRODUCTION Patients after solid organ transplantation are at an increased risk for microbial infections. Due to therapeutic immunosuppression, the response to active immunizations may be reduced. The serological efficacy of pneumococcal and influenza vaccination was studied in heart transplant recipients. PATIENTS AND METHODS Sixteen patients over 1 year after heart transplantation and control patients were immunized with a 23-valent pneumococcal vaccine and a triple-split influenza vaccine. Pre- and postvaccinal antibody titers were serologically determined, including quantitation of specific antibodies against nine pneumococcal serotypes. RESULTS Both vaccines were well tolerated without systemic reactions or infectious complications. Median postvaccinal pneumococcal antibody titers in the transplant patients were comparable to controls (5513 U/ml, range: 694-41007, vs. 5490 U/ml, range: 1088-38042; P=NS); vaccination was successful in 23/23 (100%) of controls and in 15/16 (94% plus 1 borderline positive case) of the transplant recipients. Specific antibody titers were similar for eight of nine serotypes; only the immune response against serotype 3 was reduced after transplantation. The efficacy of influenza vaccination was significantly impaired in transplant patients against all three virus strains (62% vs. 97%, P<0.01/50% vs. 94%, P<0.001/37% vs. 80%, P<0.01), but 9/16 (56%) of patients still showed a sufficient immune response to two out of three virus strains. No clinical or demographic predictors of successful vaccination could be established. CONCLUSIONS Pneumococcal vaccination under cyclosporine-based immunosuppression after heart transplantation is safe and equally effective as in healthy controls. In contrast, the immune response to influenza vaccination is significantly reduced, although not completely abolished. This differential response might be accounted for by T cell-independent antibody production against polysaccharide antigens contained in the pneumococcal vaccine.

Assessment of disease severity and outcome in patients with systemic light-chain amyloidosis by the high-sensitivity troponin T assay

Cardiac biomarkers provide prognostic information in light-chain amyloidosis (AL). Thus, a novel high-sensitivity cardiac troponin T (hs-TnT) assay may improve risk stratification. hs-TnT was assessed in 163 patients. Blood levels were higher with cardiac than renal or other organ involvement and were related to the severity of cardiac involvement. Increased sensitivity was not associated with survival benefit. Forty-seven patients died during follow-up (22.3 ± 1.0 months). Nonsurvivors had higher hs-TnT than survivors. Outcome was worse if hs-TnT more than or equal to 50 ng/L and best less than 3 ng/L. Survival of patients with hs-TnT 3 to 14 ng/L did not differ from patients with moderately increased hs-TnT (14-50 ng/L), but was worse if interventricular septum was more than or equal to 15 mm. Discrimination according to the Mayo staging system was only achieved by the use of the hs-TnT assay, but not by the fourth-generation troponin T assay. Multivariate analysis revealed hs-TnT, NT-proBNP, and left ventricular impairment as independent risk factors for survival. hs-TnT and NT-proBNP predicted survival, even after exclusion of patients with impaired renal function. Plasma levels of the hs-TnT assay are associated with the clinical, morphologic, and functional severity of cardiac AL amyloidosis and could provide useful information for clinicians on cardiac involvement and outcome.

Non‐invasive predictors of survival in cardiac amyloidosis

Patients with cardiac amyloidosis (CA) have increased mortality.

Elevated serum concentrations of cardiac troponin T in acute allograft rejection after human heart transplantation

OBJECTIVES This study evaluates the concept and diagnostic efficacy of using serum troponin T for the detection of cardiac graft rejection. BACKGROUND Cardiac troponin T is a cardiospecific myofibrillar protein, which is only detectable in the circulation after cardiac myocyte damage. It might be expected to be released during acute heart allograft rejection, allowing noninvasive rejection diagnosis. METHODS In 35 control subjects and in 422 samples from 95 clinically unremarkable heart allograft recipients more than 3 months postoperatively, troponin T serum concentrations were compared to the histological grade of acute graft rejection in concurrent endomyocardial biopsies. RESULTS Mean troponin T serum concentrations were identical in control subjects (23.2 +/- 1.4 ng/liter) and in heart transplant recipients without graft rejection (International Society for Heart and Lung Transplantation [ISHLT] grade 0; 22.4 +/- 1.7 ng/liter). Mean troponin T concentrations increased in parallel with the severity of graft rejection (ISHLT grade 1: 27.8 +/- 1.8 ng/liter; grade 2: 33.2 +/- 2.7 ng/liter; grade 3A: 54.6 +/- 6.5 ng/liter; grade 3B and 4: 105.4 +/- 53.7 ng/liter; p < 0.001 for grades 3 and 4 vs. grades 0 and 1). The proportion of positive samples also increased in parallel with rejection severity, reaching 100% in rejections of grade 3B and 4. Sensitivity and specificity for the detection of significant graft rejection (ISHLT grade 3/4) were 80.4% and 61.8%, respectively. The negative predictive value was most remarkable with 96.2%. Intraindividual longitudinal analysis of troponin T levels and biopsy results in 15 patients during long-term follow-up confirmed these findings. CONCLUSIONS The present data demonstrate that acute allograft rejection after human heart transplantation is often associated with increased serum concentrations of troponin T. All cases of serious forms of graft rejection would have been detected before the development of clinical symptoms. Measurement of troponin T levels may become a useful ancillary parameter for noninvasive rejection diagnosis, being most valuable in the exclusion of severe cardiac graft rejection.

Human Vascular Endothelial Cells Stimulate Memory But Not Naive CD8+ T Cells to Differentiate into CTL Retaining an Early Activation Phenotype

Endothelial cell (EC)-selective alloreactive CTL may mediate alloimmune vascular injury. In the present study, EC-selective CTL were generated in cocultures of purified human CD8+ T cells with allogeneic EC and were compared with conventional CTL against corresponding B lymphoblastoid cells (BLC). EC caused activation and expansion of memory but not naive CD8+ T cells, which differentiated into EC-selective CTL that retained high surface expression of CD69, CD25, and CD62L and displayed low intracellular perforin content. In contrast, BLC-stimulated CTL could be generated from naive or memory CD8+ T cells and showed a more mature phenotype (low CD69, CD25, and CD62L with higher levels of perforin). The expansion of alloreactive T cells by EC stimulation was 5- to 20-fold less effective than in corresponding BLC-stimulated cultures, accounting for a reduction in the assayable cytotoxicity of individual microcultures. In these IL-2-supplemented cocultures, no effect on CTL generation or phenotype was observed by mAb blocking of costimulation provided by LFA-3, ICAM-1, or CD40, by addition of comitogenic anti-CD28 mAb, or by preactivation of EC with CD40 ligand. Cyclosporine inhibited CTL expansion and cytotoxicity similarly in both EC- and BLC-stimulated cultures but did not affect the phenotype of those CTL that did emerge. This study extends the characterization of endothelium as an immunoregulatory cell type distinct from conventional APC and may explain why graft rejection within the arterial intima, an anatomic compartment in which EC may be the primary type of APC, is separable from rejection in the graft parenchyma.