Mesenchymal Stem Cells Derived Extracellular Vesicles Alleviate Traumatic Hemorrhagic Shock Induced Hepatic Injury via IL-10/PTPN22-Mediated M2 Kupffer Cell Polarization

Traumatic hemorrhagic shock (THS) is a major cause of mortality and morbidity worldwide in severely injured patients. Mesenchymal stem cells (MSCs) possess immunomodulatory properties and tissue repair potential mainly through a paracrine pathway mediated by MSC-derived extracellular vesicles (MSC-EVs). Interleukin 10 (IL-10) is a potent anti-inflammatory cytokine that plays a crucial role during the inflammatory response, with a broad range of effects on innate and adaptive immunity, preventing damage to the host and maintaining normal tissue homeostasis. However, the function and mechanism of IL-10 in MSC-mediated protective effect in THS remain obscure. Here, we show that MSCs significantly attenuate hepatic injury and inflammation from THS in mice. Notably, these beneficial effects of MSCs disappeared when IL-10 was knocked out in EVs or when recombinant IL-10 was administered to mice. Mechanistically, MSC-EVs function to carry and deliver IL-10 as cargo. WT MSC-EVs restored the function of IL-10 KO MSCs during THS injury. We further demonstrated that EVs containing IL-10 mainly accumulated in the liver during THS, where they were captured by Kupffer cells and induced the expression of PTPN22. These effects subsequently shifted Kupffer cells to an anti-inflammatory phenotype and mitigated liver inflammation and injury. Therefore, our study indicates that MSC-EVs containing IL-10 alleviate THS-induced hepatic injury and may serve as a cell-free therapeutic approach for THS.

Role of TLR5 in the Translocation and Dissemination of Commensal Bacteria in the Intestine after Traumatic Hemorrhagic Shock

Enterogenous infection is a major cause of death during traumatic hemorrhagic shock (THS). It has been reported that Toll-like receptor 5 (TLR5) plays an integral role in regulating mucosal immunity and intestinal homeostasis of the microbiota. However, the roles played by TLR5 on intestinal barrier maintenance and commensal bacterial translocation post-THS are poorly understood. In this research, we established THS models in wild-type (WT) and Tlr5−/− (genetically deficient in TLR5 expression) mice. We found that THS promoted bacterial translocation, while TLR5 deficiency played a protective role in preventing commensal bacteria dissemination after THS. Furthermore, intestinal microbiota analysis uncovered that TLR5 deficiency enhanced the mucosal biological barrier by decreasing RegIIIγ-mediated bactericidal activity against G+ anaerobic bacteria. We then sorted small intestinal TLR5+ lamina propria dendritic cells (LPDCs) and analyzed TH1 differentiation in the intestinal lamina propria and a coculture system consisting of LPDCs and naïve T cells. Although TLR5 deficiency attenuated the regulation of TH1 polarization by LPDCs, it conferred stability to the cells during THS. Moreover, retinoic acid (RA) released from TLR5+ LPDCs could play a key role in modulating TH1 polarization. We also found that gavage administration of RA alleviated bacterial translocation in THS-treated WT mice. In summary, we documented that TLR5 signaling plays a pivotal role in regulating RegIIIγ-induced killing of G+ anaerobic bacteria, and LPDCs mediated TH1 differentiation via RA. These processes prevent intestinal bacterial translocation and enterogenous infection after THS, suggesting that therapeutically targeting LPDCs or gut microbiota can interfere with bacterial translocation after THS.

Therapeutic Potential of Mesenchymal Stromal Cell-Derived Extracellular Vesicles in the Prevention of Organ Injuries Induced by Traumatic Hemorrhagic Shock

Severe trauma is the principal cause of death among young people worldwide. Hemorrhagic shock is the leading cause of death after severe trauma. Traumatic hemorrhagic shock (THS) is a complex phenomenon associating an absolute hypovolemia secondary to a sudden and significant extravascular blood loss, tissue injury, and, eventually, hypoxemia. These phenomena are responsible of secondary injuries such as coagulopathy, endotheliopathy, microcirculation failure, inflammation, and immune activation. Collectively, these dysfunctions lead to secondary organ failures and multi-organ failure (MOF). The development of MOF after severe trauma is one of the leading causes of morbidity and mortality, where immunological dysfunction plays a central role. Damage-associated molecular patterns induce an early and exaggerated activation of innate immunity and a suppression of adaptive immunity. Severe complications are associated with a prolonged and dysregulated immune–inflammatory state. The current challenge in the management of THS patients is preventing organ injury, which currently has no etiological treatment available. Modulating the immune response is a potential therapeutic strategy for preventing the complications of THS. Mesenchymal stromal cells (MSCs) are multipotent cells found in a large number of adult tissues and used in clinical practice as therapeutic agents for immunomodulation and tissue repair. There is growing evidence that their efficiency is mainly attributed to the secretion of a wide range of bioactive molecules and extracellular vesicles (EVs). Indeed, different experimental studies revealed that MSC-derived EVs (MSC-EVs) could modulate local and systemic deleterious immune response. Therefore, these new cell-free therapeutic products, easily stored and available immediately, represent a tremendous opportunity in the emergency context of shock. In this review, the pathophysiological environment of THS and, in particular, the crosstalk between the immune system and organ function are described. The potential therapeutic benefits of MSCs or their EVs in treating THS are discussed based on the current knowledge. Understanding the key mechanisms of immune deregulation leading to organ damage is a crucial element in order to optimize the preparation of EVs and potentiate their therapeutic effect.

Over my dead body: Self-determination, proxy consent, and proportionate reason in the treatment of a Jehovah's Witness patient with severe traumatic hemorrhagic shock

When a Jehovah’s Witness patient is traumatically injured, the lack of uniform professional consensus guidelines and the cultural knowledge deficit of many clinicians adds an additional layer of legal and ethical complexity to the inherent difficulty of managing a critically ill patient. We present here the case of an incapacitated Jehovah's Witness patient with severe traumatic hemorrhagic shock. We go on to discuss the historical and contemporary case law on proxy refusal of blood transfusion for the incapacitated adult, as well as the ethics of self-determination and the application of the principle of proportionate reason in the management of the critically injured Jehovah's Witness patient.

Plasma and rhADAMTS13 reduce trauma-induced organ failure by restoring the ADAMTS13-VWF axis

Trauma-induced organ failure is characterized by endothelial dysfunction. The aim of this study was to investigate the role of von Willebrand factor (VWF) and its cleaving enzyme, ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motifs, member 13) in the occurrence of endothelial permeability and organ failure in trauma. In an observational study in a level-1 trauma center, 169 adult trauma patients with clinical signs of shock and/or severe injuries were included. Trauma was associated with low ADAMTS13 and high VWF antigen levels, thus generating an imbalance of ADAMTS13 to VWF. Patients who developed organ failure (23%) had greater ADAMTS13-to-VWF imbalances, persistently lower platelet counts, and elevated levels of high-molecular-weight VWF multimers compared with those without organ failure, suggesting microthrombi formation. To investigate the effect of replenishing low ADAMTS13 levels on endothelial permeability and organ failure using either recombinant human ADAMTS13 (rhADAMTS13) or plasma transfusion, a rat model of trauma-induced shock and transfusion was used. Rats in traumatic hemorrhagic shock were randomized to receive crystalloids, crystalloids supplemented with rhADAMTS13, or plasma transfusion. A 70-kDa fluorescein isothiocyanate–labeled dextran was injected to determine endothelial leakage. Additionally, organs were histologically assessed. Both plasma transfusion and rhADAMTS13 were associated with a reduction in pulmonary endothelial permeability and organ injury when compared with resuscitation with crystalloids, but only rhADAMTS13 resulted in significant improvement of a trauma-induced decline in ADAMTS13 levels. We conclude that rhADAMTS13 and plasma transfusion can reduce organ failure following trauma. These findings implicate the ADAMTS13-VWF axis in the pathogenesis of organ failure.

Lessons Learned From the Battlefield and Applicability to Veterinary Medicine – Part 2: Transfusion Advances

Since the inception of recent conflicts in Afghanistan and Iraq, transfusion practices in human military medicine have advanced considerably. Today, US military physicians recognize the need to replace the functionality of lost blood in traumatic hemorrhagic shock and whole blood is now the trauma resuscitation product of choice on the battlefield. Building on wartime experiences, military medicine is now one of the country's strongest advocates for the principle of hemostatic resuscitation using whole blood or balanced blood components as the primary means of resuscitation as early as possibly following severe trauma. Based on strong evidence to support this practice in human combat casualties and in civilian trauma care, military veterinarians strive to practice similar hemostatic resuscitation for injured Military Working Dogs. To this end, canine whole blood has become increasingly available in forward environments, and non-traditional storage options for canine blood and blood components are being explored for use in canine trauma. Blood products with improved shelf-life and ease of use are not only useful for military applications, but may also enable civilian general and specialty practices to more easily incorporate hemostatic resuscitation approaches to canine trauma care.