Enhancing arginase 2 expression using target site blockers as a strategy to modulate macrophage phenotype.

Macrophages are plastic cells playing a crucial role in innate immunity. While fundamental in responding to infections, when persistently maintained in a pro-inflammatory state they can initiate and sustain inflammatory diseases. Therefore, a strategy that reprograms pro-inflammatory macrophages toward an anti-inflammatory phenotype could hold therapeutic potential in that context. We have recently shown that arginase 2 (Arg2), a mitochondrial enzyme involved in arginine metabolism, promotes the resolution of inflammation in macrophages and it is targeted by miR-155. Here, we designed and tested a target site blocker (TSB) that specifically interferes and blocks the interaction between miR-155 and Arg2 mRNA, leading to Arg2 increased expression and activity. In bone marrow-derived macrophages transfected with Arg2 TSB (in the presence or absence of the pro-inflammatory stimulus LPS), we observed an overall shift of the polarization status of macrophages toward an anti-inflammatory phenotype, as shown by significant changes in surface markers (CD80 and CD71), metabolic parameters (mitochondrial oxidative phosphorylation) and cytokines secretion (IL-1ß, IL-6, and TNF). Moreover, in an in vivo model of LPS-induced acute inflammation, intraperitoneal administration of Arg2 TSB led to an overall decrease in systemic levels of pro-inflammatory cytokines. Overall, this proof-of-concept strategy represent a promising approach to modulating macrophage phenotype.

Mitochondrial arginase-2 is essential for IL-10 metabolic reprogramming of inflammatory macrophages.

Mitochondria are important regulators of macrophage polarisation. Here, we show that arginase-2 (Arg2) is a microRNA-155 (miR-155) and interleukin-10 (IL-10) regulated protein localized at the mitochondria in inflammatory macrophages, and is critical for IL-10-induced modulation of mitochondrial dynamics and oxidative respiration. Mechanistically, the catalytic activity and presence of Arg2 at the mitochondria is crucial for oxidative phosphorylation. We further show that Arg2 mediates this process by increasing the activity of complex II (succinate dehydrogenase). Moreover, Arg2 is essential for IL-10-mediated downregulation of the inflammatory mediators succinate, hypoxia inducible factor 1α (HIF-1α) and IL-1ß in vitro. Accordingly, HIF-1α and IL-1ß are highly expressed in an LPS-induced in vivo model of acute inflammation using Arg2-/- mice. These findings shed light on a new arm of IL-10-mediated metabolic regulation, working to resolve the inflammatory status of the cell.

The Role of MicroRNAs in Repair Processes in Multiple Sclerosis.

Multiple sclerosis (MS) is an autoimmune disorder characterised by demyelination of central nervous system neurons with subsequent damage, cell death and disability. While mechanisms exist in the CNS to repair this damage, they are disrupted in MS and currently there are no treatments to address this deficit. In recent years, increasing attention has been paid to the influence of the small, non-coding RNA molecules, microRNAs (miRNAs), in autoimmune disorders, including MS. In this review, we examine the role of miRNAs in remyelination in the different cell types that contribute to MS. We focus on key miRNAs that have a central role in mediating the repair process, along with several more that play either secondary or inhibitory roles in one or more aspects. Finally, we consider the current state of miRNAs as therapeutic targets in MS, acknowledging current challenges and potential strategies to overcome them in developing effective novel therapeutics to enhance repair mechanisms in MS.

Surgical Anatomy of Vaginal Hysterectomy-Impact of a Resident-Constructed Simulation Model.

OBJECTIVES: Obstetrics and gynecology residents are less prepared to perform vaginal hysterectomy (VH), despite its advantages over other hysterectomy routes. The American Congress of Obstetricians and Gynecologists and Council on Resident Education in Obstetrics and Gynecology have prioritized simulation training in VH. Our objective was to improve residents' understanding of surgical anatomy of VH using a resident-constructed, low-cost, low-fidelity model. METHODS: A single simulation session was held in November 2016. Residents constructed a pelvic model, guided by 2 surgeons. A pretest and a posttest were administered. Experienced-based responses were tabulated for frequencies and contents. Improvement on knowledge-based questions was assessed using McNemar's test. RESULTS: Of 20 residents, 16 completed the pretest and 14 (70%) completed pretests and posttests. One hundred percent of postgraduate year (PGY)-4 had performed greater than 10 VH (11-21) and 75% of PGY-3 had performed 5 to 12 VH. Although 75% of PGY-3 and 100% of PGY-4 felt comfortable performing VH, baseline knowledge of essential surgical anatomy of VH was low (65.8%). The PGY-3 and -4 group (n=8) experienced a mean improvement of 24.4% (mean pretest score 65.8% vs mean posttest score 90%; 95% confidence interval, +14.1% to +33.3%, P=0.0005). The PGY-1 and -2 groups (n=6) experienced a mean improvement of 43.3% (mean pretest score, 41.7% vs mean posttest score, 85%; 95% confidence interval, +26.7% to +59.2%, P=0.001). After the session, all residents reported improved understanding surgical anatomy of VH and "more hands-on sessions" was the most frequently requested teaching aid. CONCLUSIONS: Residents desire additional model-based simulation training in VH, and such structured, model-based simulations can identify and address gaps in resident knowledge of surgical anatomy of this important operation.