Burn Injury Induces Proinflammatory Plasma Extracellular Vesicles That Associate with Length of Hospital Stay in Women: CRP and SAA1 as Potential Prognostic Indicators

Abstract

Severe burn injury is a devastating form of trauma that results in persistent immune dysfunction with associated morbidity and mortality. The underlying drivers of this immune dysfunction remain elusive, and there are no prognostic markers to identify at-risk patients. Extracellular vesicles (EVs) are emerging as drivers of immune dysfunction as well as biomarkers. We investigated if EVs after burn injury promote macrophage activation and assessed if EV contents can predict length of hospital stay. EVs isolated early from mice that received a 20% total body surface area (TBSA) burn promoted proinflammatory responses in cultured splenic macrophages. Unbiased LC-MS/MS proteomic analysis of early EVs (<72 h post-injury) from mice and humans showed some similarities including enrichment of acute phase response proteins such as CRP and SAA1. Semi-unbiased assessment of early human burn patient EVs found alterations consistent with increased proinflammatory signaling and loss of inhibition of CRP expression. In a sample of 50 patients with large burn injury, EV SAA1 and CRP were correlated with TBSA injury in both sexes and were correlated with length of hospital stay in women. These findings suggest that EVs are drivers of immune responses after burn injury and their content may predict hospital course.

Burn Injury-Induced Extracellular Vesicle Production and Characteristics

“…EV cargo composition and molecular contents reflect the physiological state and activation status of cells and tissues of their origin, thus providing distinctive signature for cellular functions and tissue injuries in diseases (3, 7). Burn injury triggers a biphasic immune response: acute inflammatory phase (first 48–72 h) followed by immunosuppression (19). Our results show that burn EV dynamics follows the course of this response.…”

“…Additionally, the cargo molecules in EVs may be affected by different demographics and clinical conditions of burn patients. For example, certain EV cargo proteins, such as SAA1 and CRP, are thought to be predictive for the length of hospital stay in female, but not male burn patients (19).…”

“…In burn patients, the plasma concentration of leukocyte-derived EVs is thought to be associated with mortality (18). The levels of several EV cargo proteins, such as serum amyloid A1 (SAA1) and C-reactive protein (CRP), are correlated with the length of hospital stay in female burn patients (19). In addition, burn EVs have been reported to cause macrophage activation and cytokine release (20).…”

Ethanol Induces Secretion of Proinflammatory Extracellular Vesicles That Inhibit Adult Hippocampal Neurogenesis Through G9a/GLP-Epigenetic Signaling

“…Media samples were diluted in 0.02 µm filtered PBS and assessed by NTA on the ParticleMetrix ZetaView ® PMX-420 Video Microscope in the Nanomedicines Characterization Core Facility at UNC as we have reported previously (31,(49)(50)(51).…”

“…Each culture well had 10-13 hippocampal slices (300µm thickness). 1.4x10 10 EVs were added to each recipient culture which is ~20% of the total slice media EVs at baseline, similar to our previous studies (31,49,50). At the end of EV treatment, slices were removed for either mRNA analysis by RT-PCR or immunostaining for measurement of neurogenesis.…”