Exercise training reverses cardiac aging phenotypes associated with heart failure with preserved ejection fraction in male mice.

Heart failure with preserved ejection fraction (HFpEF) is the most common type of HF in older adults. Although no pharmacological therapy has yet improved survival in HFpEF, exercise training (ExT) has emerged as the most effective intervention to improving functional outcomes in this age-related disease. The molecular mechanisms by which ExT induces its beneficial effects in HFpEF, however, remain largely unknown. Given the strong association between aging and HFpEF, we hypothesized that ExT might reverse cardiac aging phenotypes that contribute to HFpEF pathophysiology and additionally provide a platform for novel mechanistic and therapeutic discovery. Here, we show that aged (24-30 months) C57BL/6 male mice recapitulate many of the hallmark features of HFpEF, including preserved left ventricular ejection fraction, subclinical systolic dysfunction, diastolic dysfunction, impaired cardiac reserves, exercise intolerance, and pathologic cardiac hypertrophy. Similar to older humans, ExT in old mice improved exercise capacity, diastolic function, and contractile reserves, while reducing pulmonary congestion. Interestingly, RNAseq of explanted hearts showed that ExT did not significantly modulate biological pathways targeted by conventional HF medications. However, it reversed multiple age-related pathways, including the global downregulation of cell cycle pathways seen in aged hearts, which was associated with increased capillary density, but no effects on cardiac mass or fibrosis. Taken together, these data demonstrate that the aged C57BL/6 male mouse is a valuable model for studying the role of aging biology in HFpEF pathophysiology, and provide a molecular framework for how ExT potentially reverses cardiac aging phenotypes in HFpEF

Electrocardiographic features of immune checkpoint inhibitor associated myocarditis.

BACKGROUND: Myocarditis is a highly morbid complication of immune checkpoint inhibitor (ICI) use that remains inadequately characterized. The QRS duration and the QTc interval are standardized electrocardiographic measures that are prolonged in other cardiac conditions; however, there are no data on their utility in ICI myocarditis. METHODS: From an international registry, ECG parameters were compared between 140 myocarditis cases and 179 controls across multiple time points (pre-ICI, on ICI prior to myocarditis, and at the time of myocarditis). The association between ECG values and major adverse cardiac events (MACE) was also tested. RESULTS: Both the QRS duration and QTc interval were similar between cases and controls prior to myocarditis. When compared with controls on an ICI (93±19 ms) or to baseline prior to myocarditis (97±19 ms), the QRS duration prolonged with myocarditis (110±22 ms, p CONCLUSIONS: The QRS duration is increased in ICI myocarditis and is associated with increased MACE risk. Use of this widely available ECG parameter may aid in ICI myocarditis diagnosis and risk-stratification

Signals governing the recruitment of T lineage progenitors to the thymus

T cells are a lymphocyte lineage critical for immune defense from a range of pathogens. T cells uniquely complete the majority of their development outside the bone marrow in a specialized organ, the thymus. As self-renewing progenitors are not found in the thymus, continuous T cell production requires the importation of bone marrow-derived progenitors into the thymus via the blood. Thymic settling is selective, as only a subset of bone marrow progenitors with T lineage potential can enter the thymus from blood. The chemokine receptor CCR9 mediates at least a part of this selectivity, but progenitors deficient for CCR9 still settle the thymus, suggesting the involvement of additional signals. In this work, we have assessed the molecules that underlie unirradiated thymic settling and have also investigated their role following irradiation. We first identified a second chemokine receptor, CCR7, which together with CCR9 recruits circulating progenitors into the unirradiated thymus. The absence of both receptors confers a near-absolute defect on thymic settling under competitive conditions. Acutely after irradiation, however, progenitors lacking both receptors gain efficient access to the thymus. We found that the magnitude of early thymic and peripheral T cell reconstitution after irradiation is directly linked to the number of progenitors that enter the thymus. Yet bone marrow progenitors with thymic settling capacity suffer defective reconstitution following bone marrow transplantation. From these results, we conclude that thymic settling signals are altered briefly by irradiation. Furthermore, the delayed recovery of the T lineage can be attributed in part to the diminished delivery of progenitors to the thymus after bone marrow transplantation

T cell development requires constraint of the myeloid regulator C/EBP-α by the Notch target and transcriptional repressor Hes1

International audienceNotch signaling induces gene expression of the T cell lineage and discourages alternative fate outcomes. Hematopoietic deficiency in the Notch target Hes1 results in severe T cell lineage defects; however, the underlying mechanism is unknown. We found here that Hes1 constrained myeloid gene-expression programs in T cell progenitor cells, as deletion of the myeloid regulator C/EBP-α restored the development of T cells from Hes1-deficient progenitor cells. Repression of Cebpa by Hes1 required its DNA-binding and Groucho-recruitment domains. Hes1-deficient multipotent progenitor cells showed a developmental bias toward myeloid cells and dendritic cells after Notch signaling, whereas Hes1-deficient lymphoid progenitor cells required additional cytokine signaling for diversion into the myeloid lineage. Our findings establish the importance of constraining developmental programs of the myeloid lineage early in T cell development

Pericardial disease in patients treated with immune checkpoint inhibitors

Background There are limited data on the occurrence, associations and outcomes of pericardial effusions and pericarditis on or after treatment with immune checkpoint inhibitors (ICIs).Methods This was a retrospective study at a single academic center that compared 2842 consecutive patients who received ICIs with 2699 age- and cancer-type matched patients with metastatic disease who did not receive ICI. A pericardial event was defined as a composite outcome of pericarditis and new or worsening moderate or large pericardial effusion. The endpoints were obtained through chart review and were blindly adjudicated. To identify risk factors associated with a pericardial event, we compared patients who developed an event on an ICI with patients treated with an ICI who did not develop a pericardial event. Cox proportional-hazard model and logistical regression analysis were performed to study the association between ICI use and pericardial disease as well as pericardial disease and mortality. An additional 6-week landmark analysis was performed to account for lead-time bias.Results There were 42 pericardial events in the patients treated with ICI (n=2842) over 193 days (IQR: 64–411), yielding an incidence rate of 1.57 events per 100 person-years. There was a more than fourfold increase in risk of pericarditis or a pericardial effusion among patients on an ICI compared with controls not treated with ICI after adjusting for potential confounders (HR 4.37, 95% CI 2.09 to 9.14, p<0.001). Patients who developed pericardial disease while on an ICI had a trend for increased all-cause mortality compared with patients who did not develop a pericardial event (HR 1.53, 95% CI 0.99 to 2.36, p=0.05). When comparing those who developed pericardial disease after ICI treatment with those who did not, a higher dose of corticosteroid pre-ICI (>0.7 mg/kg prednisone) was associated with increased risk of pericardial disease (HR 2.56, 95% CI 1.00 to 6.57, p=0.049).Conclusions ICI use was associated with an increased risk of development of pericardial disease among patients with cancer and a pericardial event on an ICI was associated with a trend towards increase in mortality