Faculty Bibliography

Atherosclerosis is a disease of chronic inflammation. We investigated the roles of the cytokines IL-4 and IL-13, the classical activators of STAT6, in the resolution of atherosclerosis inflammation. Using Il4^-/-Il13^-/- mice, resolution was impaired, and in control mice, in both progressing and resolving plaques, levels of IL-4 were stably low, and IL-13 was undetectable. This suggested that IL-4 is required for atherosclerosis resolution, but collaborates with other factors. We had observed increased Wnt signaling in macrophages in resolving plaques, and human genetic data from others showed that a loss-of-function Wnt mutation was associated with premature atherosclerosis. We now find an inverse association between activation of Wnt signaling and disease severity in mice and humans. Wnt enhanced the expression of inflammation resolving factors after treatment with plaque-relevant low concentrations of IL-4. Mechanistically, activation of the Wnt pathway following lipid lowering potentiates IL-4 responsiveness in macrophages via a PGE₂/STAT3 axis.

BACKGROUND:Platelets are increasingly recognized as immune cells. As such, they are commonly seen to induce and perpetuate inflammation, however, anti-inflammatory activities are increasingly attributed to them. Atherosclerosis is a chronic inflammatory condition. Similar to other inflammatory conditions, the resolution of atherosclerosis requires a shift in macrophages to an M2 phenotype, enhancing their efferocytosis and cholesterol efflux capabilities. OBJECTIVES/OBJECTIVE:To assess the effect of platelets on macrophage phenotype. METHODS:In several in vitro models employing murine (RAW264.7 and bone marrow derived macrophages) and human (THP-1 and monocyte-derived macrophages) cells, we exposed macrophages to media in which non-agonized human platelets were cultured for 60 minutes (platelet conditioned media; PCM) and assessed the impact on macrophage phenotype and function. RESULTS:). CONCLUSIONS:PCM induces an anti-inflammatory, pro-resolving phenotype in macrophages. Our findings suggest that therapies targeting hemostatic properties of platelets, while not influencing pro-resolving, immune-related activities, could be beneficial for the treatment of atherothrombotic disease.

Background Arrhythmogenic cardiomyopathy (ACM) can mimic inflammatory processes. We present a complex patient with scleroderma (Sc)-dermatomyositis overlap syndrome (Sc-DM) and cardiac disease. Case A 57-year-old woman with family history of Sc presented with progressive weakness, dyspnea, edema, and Raynaud's (1A). Troponin was 1.6 ng/mL and CRP was 13.2 mg/L. EKGs revealed sinus rhythm with RBBB and AV sequential pacing with multifocal PVCs (1B-C). CT chest showed bibasilar fibrosis (1D). Echocardiography revealed biventricular dysfunction. Cardiac catheterization showed non-obstructive coronaries and a cardiac index of 1.8 L/min/m2. Cardiac MRI had diffuse biventricular subendocardial late gadolinium enhancement (1E). Electromyography revealed proximal myopathy. Rheumatologic workup was consistent with seronegative Sc-DM. Decision-making She was treated with steroids, mycophenolate, IV immunoglobulins, diuretics, and inotropes. Her course was complicated by recurrent VT cardiac arrests, prompting escalation to VA-ECMO. She underwent cardiac transplant on day 9 of ECMO. Pathology revealed biventricular fibrofatty replacement consistent with ACM (1F-G), patchy fibrosis of the pericardium, and mitral valve with thickened and fused chordae suggestive of inflammatory changes from Sc (1H-I). Conclusion This case highlights an atypical presentation of ACM in a patient with Sc-DM and the multidisciplinary approach necessary for proper diagnosis and management. [Figure presented]
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For decades, intravenous immunoglobulin (IVIg) has provided safe and effective therapy for immunodeficient patients. This proof-of-principle study describes a novel approach to generate personalized IVIg for chronic, antibiotic-resistant infection in real time.

Antibody class switch recombination (CSR) in B lymphocytes joins two DNA double-strand breaks (DSBs) lying 100-200 kb apart within switch (S) regions in the immunoglobulin heavy-chain locus (IgH). CSR-activated B lymphocytes generate multiple S-region DSBs in the donor Sμ and in a downstream acceptor S region, with a DSB in Sμ being joined to a DSB in the acceptor S region at sufficient frequency to drive CSR in a large fraction of activated B cells. Such frequent joining of widely separated CSR DSBs could be promoted by IgH-specific or B-cell-specific processes or by general aspects of chromosome architecture and DSB repair. Previously, we found that B cells with two yeast I-SceI endonuclease targets in place of Sγ1 undergo I-SceI-dependent class switching from IgM to IgG1 at 5-10% of normal levels. Now, we report that B cells in which Sγ1 is replaced with a 28 I-SceI target array, designed to increase I-SceI DSB frequency, undergo I-SceI-dependent class switching at almost normal levels. High-throughput genome-wide translocation sequencing revealed that I-SceI-generated DSBs introduced in cis at Sμ and Sγ1 sites are joined together in T cells at levels similar to those of B cells. Such high joining levels also occurred between I-SceI-generated DSBs within c-myc and I-SceI- or CRISPR/Cas9-generated DSBs 100 kb downstream within Pvt1 in B cells or fibroblasts, respectively. We suggest that CSR exploits a general propensity of intrachromosomal DSBs separated by several hundred kilobases to be frequently joined together and discuss the relevance of this finding for recurrent interstitial deletions in cancer.