Bioactive matrix fragments (matrikines) have been identified in a myriad of disorders, but their impact on the evolution of airway inflammation has not been demonstrated. We recently described a pathway where the matrikine and neutrophil chemoattractant proline–glycine–proline (PGP) could be degraded by the enzyme leukotriene A4 hydrolase (LTA4H). LTA4H classically functions in the generation of pro-inflammatory leukotriene B4, thus LTA4H exhibits opposing pro- and anti-inflammatory activities. The physiological significance of this secondary anti-inflammatory activity remains unknown. Here we show, using readily resolving pulmonary inflammation models, that loss of this secondary activity leads to more pronounced and sustained inflammation and illness owing to PGP accumulation. PGP elicits an exacerbated neutrophilic inflammation and protease imbalance that further degrades the extracellular matrix, generating fragments that perpetuate inflammation. This highlights a critical role for the secondary anti-inflammatory activity of LTA4H and thus has consequences for the generation of global LTA4H inhibitors currently being developed.

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Background: Up to 50% of essential tremor patients are refractory to medication and require alternative treatment to achieve tremor relief. This study aimed to identify and analyze evidence supporting the use of the emerging magnetic resonance-guided focused ultrasound (MRgFUS) compared to alternative stimulatory and ablative interventions for the treatment of medication-refractory essential tremor: radiofrequency thalamotomy, unilateral deep brain stimulation (DBS), and stereotactic radiosurgery. Methods: A systematic literature review was conducted to identify clinical, health-related quality of life (HRQoL), and economic evidence for each intervention. Because of the lack of comparative evidence captured, a feasibility assessment was performed to determine possible comparisons between interventions, and newly established matchingadjusted indirect comparison and simulated treatment comparison techniques were used to conduct a comparison between unilateral DBS aggregate data and MRgFUS individual patient data. Results: The systematic literature review identified 1,559 records, and screening yielded 46 relevant articles. The captured studies demonstrated that radiofrequency thalamotomy, DBS, stereotactic radiosurgery, and MRgFUS all exhibit clinical efficacy, with variation in onset and duration of tremor relief, and are each associated with a unique safety profile. The matching-adjusted indirect comparison and simulated treatment comparison results demonstrated no evidence of a difference in efficacy (measured by Clinical Rating Scale for Tremor Total) and HRQoL (measured by Clinical Rating Scale for Tremor Part C) outcomes between MRgFUS and unilateral DBS in the short term (r12 months). Conclusions: This study provides preliminary evidence that MRgFUS could elicit similar short-term tremor-and HRQoL-related benefits to DBS, the current standard of care, and allowed for the first robust statistical comparison between these interventions.