Rationale: Heart failure caused by ischemic cardiomyopathy is the leading cause of death and disability in the USA and world, accounting for 10 million deaths in 2016. Sphingolipids including ceramides and sphingosine-1-phosphate have been demonstrated to play roles in myocardial injury. In general, these lipids are synthesized from serine palmitoyltransferase (SPT) derived using serine and palmitoyl-CoA. While the standard SPT enzyme exists as a heterodimer of two subunits, Sptlc1 and Sptlc2, a new subunit was recently discovered, Sptlc3, which enables the SPT complex to use myristoyl-CoA, thereby synthesizing a previously underappreciated group of atypical sphingolipids. We previously demonstrated that these atypical lipids are a major component of myocardial sphingolipid pools. Furthermore, in contrast to canonical sphingolipids, the atypical lipids promote cardiomyocyte apoptosis. Therefore, the goal of this research is to determine the contribution of these novel lipids to cardiomyocyte apoptosis and therefore whether they may contribute to ischemic injury. Objectives: To determine the contribution of Sptlc3 and atypical sphingolipids to cardiomyocyte apoptosis and ischemic injury and to assess the potential relevance of Sptlc3 to human HF. Methods: Murine primary cardiac fibroblasts and cardiomyocytes were isolated and subject to ischemic induction. Following this, cells were analyzed with TUNEL staining, lipidomic analysis or treatment with a Sptlc3 mimetic. Results: Ischemic cells show significantly increased Sptlc3 expression, non-canonical sphingolipids in the sphingolipid pool and apoptotic cells as compared to their controls. The cells treated with the Sptlc3 mimetic show apoptotic and a non-canonical autophagic pathway being induced in cells. Conclusions: We have identified a novel class of sphingolipids enriched in myocardium of mice with cardiomyopathies. Furthermore, the enzyme that produces these, Sptlc3, is robustly increased in human heart failure. Because the Sptlc3-derived lipids promoted cardiomyocyte apoptosis, we propose that Sptlc3 may mediate myocardial injury in ischemia.

ImportanceRetinal vein occlusion is the second most common retinal vascular disease. Bevacizumab was demonstrated in the Study of Comparative Treatments for Retinal Vein Occlusion 2 (SCORE2) to be noninferior to aflibercept with respect to visual acuity in study participants with macular edema due to central retinal vein occlusion (CRVO) or hemiretinal vein occlusion (HRVO) following 6 months of therapy. In this study, the cost-utility of bevacizumab vs aflibercept for treatment of CRVO is evaluated.ObjectiveTo investigate the relative cost-effectiveness of bevacizumab vs aflibercept for treatment of macular edema associated with CRVO or HRVO.Design, Setting, and ParticipantsThis economic evaluation study used a microsimulation cohort of patients with clinical and demographic characteristics similar to those of SCORE2 participants and a Markov process. Parameters were estimated and validated using a split-sample approach of the SCORE2 population. The simulated cohort included 5000 patients who were evaluated 100 times, each with a different set of characteristics randomly selected based on the SCORE2 trial. SCORE2 data were collected from September 2014 October 2019, and data were analyzed from October 2019 to July 2021.InterventionsBevacizumab (followed by aflibercept among patients with a protocol-defined poor or marginal response to bevacizumab at month 6) vs aflibercept (followed by a dexamethasone implant among patients with a protocol-defined poor or marginal response to aflibercept at month 6).Main Outcomes and MeasuresIncremental cost-utility ratio.ResultsThe simulation demonstrated that patients treated with aflibercept will have an expected cost $18 127 greater than those treated with bevacizumab in the year following initiation. When coupled with the lack of clinical superiority over bevacizumab (ie, patients treated with bevacizumab had a gain over aflibercept in visual acuity letter score of 4 in the treated eye and 2 in the fellow eye), these results demonstrate that first-line treatment with bevacizumab dominated aflibercept in the simulated cohort of SCORE2 participants. At current price levels, aflibercept would be considered the preferred cost-effective option only if treatment restored the patient to nearly perfect health.Conclusions and RelevanceWhile there will be some patients with CRVO-associated or HRVO-associated macular edema who will benefit from first-line treatment with aflibercept rather than bevacizumab, given the minimal differences in visual acuity outcomes and large cost differences for bevacizumab vs aflibercept, first-line treatment with bevacizumab is cost-effective for this condition.

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Allergic asthma is a pulmonary disease characterized by airway hyperresponsiveness (AhR) in response to inhaled allergens. AhR is largely mediated by allergen-specific (Ag-specific) IgE induced mast cell (MC) degranulation which drives inflammation of the airways following allergen exposure. Ag-specific IgE production requires T follicular helper 13 cells (Tfh13s) which must first be polarized by dendritic cells (DCs). The mechanisms by which DCs polarize Tfh13s, however, are unclear. We hypothesized that the Tfh13 inducing allergen Alternaria would induce a unique metabolic response compared to non-Tfh13 inducing stimuli. We found, by untargeted metabolomic analysis, that Alternaria induced accumulation of the glutamine-derived TCA cycle metabolite α-ketoglutarate compared to LPS stimulated or unstimulated DCs. Glutamine is converted to α-ketoglutarate by glutaminase (Gls), so we predicted that inhibition of Gls may suppress Tfh13 polarization by DCs. Indeed, we found that treatment with the Gls inhibitor, CB-839, reduced Tfh13 polarization and increased T follicular regulatory cells following Alternaria exposure. This finding was recapitulated in a DC adoptive transfer model, indicating that this mechanism is DC intrinsic. We next tested if CB-839 causes allergen desensitization in a model of allergic asthma. Mice were intranasally sensitized and challenged with Alternaria and intranasally treated with CB-839 or vehicle control prior to challenge. CB-839 treated mice exhibited reduced AhR, Ag-specific IgE, and airway MC degranulation. These data demonstrate that DC glutaminolysis is required for Tfh13 polarization, and that Gls inhibitors may promote allergen desensitization in allergic asthma. This work was funded by VCU's National Center for Advancing Translational Sciences (UL1TR002649) and NIAID (R56AI139658).