Autodigestion: Proteolytic Degradation and Multiple Organ Failure in Shock

Lymphatic Uptake of a Highly Lipophilic Protease Inhibitor Prodrug from a Lipid-Based Formulation is Limited by Instability in the Intestine

Dabigatran etexilate (DABE) is a lipophilic double alkyl ester prodrug of dabigatran (DAB) which is a serine protease inhibitor used clinically as an anticoagulant. Recently, translocation of serine protease enzymes, including trypsin, from the gut into the mesenteric lymph and then blood has been associated with organ failure in acute and critical illnesses (ACIs). Delivery of DABE into mesenteric lymph may thus be an effective strategy to prevent organ failure in ACIs. Most drugs access the mesenteric lymph in low quantities following oral administration, as they are rapidly transported away from the intestine via the blood. Here, we examine the potential to deliver DABE into the mesenteric lymph by promoting association with lymph lipid transport pathways via co-administration with a lipid-based formulation (LBF). A series of self-emulsifying LBFs were designed and tested in vitro for their potential to form stable DABE loaded emulsions and keep DABE solubilised and stable over time in simulated gastrointestinal conditions. The LBFs were found to form fine emulsions with a droplet size of 214 ± 30 nm and DABE was stable in the formulation. The stability of DABE in vitro in simulated intestinal conditions, plasma and lymph samples was also evaluated to ensure stability in collected samples and to evaluate whether the prodrug is likely to release active DAB. Ultimately, a highly uniform and stable self-emulsifying Type III A LBF of DABE was chosen for progression into in vivo studies in male Sprague Dawley rats to confirm the lymphatic uptake and plasma pharmacokinetics. Both in vitro and in vivo in plasma and lymph, DABE was rapidly converted to an intermediate and DAB. The main species present in vivo in both plasma and lymph was DAB and mass transport of DABE and DAB in lymph was minimal (∼0.5 % of dose). Importantly, the concentration of DABE in lymph was substantially (20-176 fold) higher than in plasma, supporting that if the prodrug were stable and did not convert to DAB in the intestine, it would be lymphatically transported. Future studies will therefore focus on optimizing the design of the prodrug and formulation to improve stability during absorption and further promote lymphatic uptake.

Lilrb4 ameliorates ileal injury in rats with hemorrhagic shock and suppresses the activation of NF-κB signaling pathway

Hemorrhagic shock (HS) leads to intestinal damage and subsequent multiple organ dysfunction syndrome. Intestinal barrier dysfunction is the main cause of multiple organ failure associated with HS. Leukocyte immunoglobulin-like receptor B4 (Lilrb4) belongs to the Ig superfamily and is a vital natural immunomodulatory receptor. The purpose of this study was to identify the role and molecular mechanism of Lilrb4 in HS-induced ileal injury. In this work, HS was established by femoral artery cannula and 90 min of HS (blood pressure, 35-40 mmHg), followed by resuscitation. RNA sequencing analysis showed that Lilrb4 was highly expressed in the ileum of HS rats. As observed, HS rats exhibited severe ileal injury, characterized by enlarged subepithelial space, edema, exfoliation and extensive loss of villi. Whereas, lentivirus system-mediated Lilrb4 overexpression considerably mitigated these alterations. HS led to increased release of markers associated with intestinal injury, which was effectively reversed by Lilrb4 overexpression. In addition, after resuscitation, Lilrb4 overexpression inhibited HS-triggered inflammatory response, as evidenced by decreased levels of proinflammatory cytokines. Lilrb4 also inhibited the activation of NF-κB signal induced by HS. Notably, Lilrb4 modulated the balance of regulatory T (Treg)-T helper 17 (Th17) cells in the mesenteric lymph node (MLN), which may also contribute to its protective role in HS progression. In aggregate, these findings confirmed that Lilrb4 overexpression protected against ileal injury caused by HS, indicating that Lilrb4 may be a potential candidate for the treatment of HS.

Viral afterlife: SARS-CoV-2 as a reservoir of immunomimetic peptides that reassemble into proinflammatory supramolecular complexes

It is unclear how severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection leads to the strong but ineffective inflammatory response that characterizes severe Coronavirus disease 2019 (COVID-19), with amplified immune activation in diverse cell types, including cells without angiotensin-converting enzyme 2 receptors necessary for infection. Proteolytic degradation of SARS-CoV-2 virions is a milestone in host viral clearance, but the impact of remnant viral peptide fragments from high viral loads is not known. Here, we examine the inflammatory capacity of fragmented viral components from the perspective of supramolecular self-organization in the infected host environment. Interestingly, a machine learning analysis to SARS-CoV-2 proteome reveals sequence motifs that mimic host antimicrobial peptides (xenoAMPs), especially highly cationic human cathelicidin LL-37 capable of augmenting inflammation. Such xenoAMPs are strongly enriched in SARS-CoV-2 relative to low-pathogenicity coronaviruses. Moreover, xenoAMPs from SARS-CoV-2 but not low-pathogenicity homologs assemble double-stranded RNA (dsRNA) into nanocrystalline complexes with lattice constants commensurate with the steric size of Toll-like receptor (TLR)-3 and therefore capable of multivalent binding. Such complexes amplify cytokine secretion in diverse uninfected cell types in culture (epithelial cells, endothelial cells, keratinocytes, monocytes, and macrophages), similar to cathelicidin's role in rheumatoid arthritis and lupus. The induced transcriptome matches well with the global gene expression pattern in COVID-19, despite using <0.3% of the viral proteome. Delivery of these complexes to uninfected mice boosts plasma interleukin-6 and CXCL1 levels as observed in COVID-19 patients.

Efficacy of Tranexamic Acid in Blood Versus Crystalloid-Resuscitated Trauma/Hemorrhagic Shock

INTRODUCTION

Whole blood (WB) or blood products are not always immediately available for repletion of lost intravascular volume in trauma/hemorrhagic shock (T/HS), and thus, resuscitation with crystalloid solutions is often necessary. Recently, we have shown enteral tranexamic acid (TXA) to be effective as a mild protease inhibitor in blood-resuscitated T/HS by counteracting proteolytic activity in and leaking from the gut with resultant preservation of systemic vascular integrity. We hypothesized that enteral TXA would improve hemodynamic stability after T/HS in the absence of blood reperfusion.

METHODS

We directly compared resuscitation with enteral TXA versus intravenous (IV) TXA in conjunction with lactated Ringer's solution (LR) or WB reperfusion in an experimental T/HS model. Rats were subjected to laparotomy and exsanguinated to a mean arterial blood pressure of 35-40 mm Hg for 90 min, followed by LR or WB reperfusion and monitored for 120 min. TXA was administered via IV (10 mg/kg) or enteral infusion (150 mM) 20 min after establishment of hemorrhage for 150 min.

RESULTS

Animals resuscitated with LR were unable to restore or maintain a survivable mean arterial blood pressure (>65 mm Hg), regardless of TXA treatment route. In contrast, rats reperfused with WB and given TXA either enterally or IV displayed hemodynamic improvements superior to WB controls.

CONCLUSIONS

Results suggest that the beneficial hemodynamic responses to enteral or IV TXA after experimental T/HS depend upon reperfusion of WB or components present in WB as TXA, regardless of delivery mode, does not have appreciable hemodynamic effects when paired with LR reperfusion.

Mesenchymal stem cell extracellular vesicles mitigate vascular permeability and injury in the small intestine and lung in a mouse model of hemorrhagic shock and trauma

BACKGROUND

Hemorrhagic shock and trauma (HS/T)-induced gut injury may play a critical role in the development of multi-organ failure. Novel therapies that target gut injury and vascular permeability early after HS/T could have substantial impacts on trauma patients. In this study, we investigate the therapeutic potential of human mesenchymal stem cells (MSCs) and MSC-derived extracellular vesicles (MSC EVs) in vivo in HS/T in mice and in vitro in Caco-2 human intestinal epithelial cells.

METHODS

In vivo, using a mouse model of HS/T, vascular permeability to a 10-kDa dextran dye and histopathologic injury in the small intestine and lungs were measured among mice. Groups were (1) sham, (2) HS/T + lactated Ringer's (LR), (3) HS/T + MSCs, and (4) HS/T + MSC EVs. In vitro, Caco-2 cell monolayer integrity was evaluated by an epithelial cell impedance assay. Caco-2 cells were pretreated with control media, MSC conditioned media (CM), or MSC EVs, then challenged with hydrogen peroxide (H2O2).

RESULTS

In vivo, both MSCs and MSC EVs significantly reduced vascular permeability in the small intestine (fluorescence units: sham, 456 ± 88; LR, 1067 ± 295; MSC, 765 ± 258; MSC EV, 715 ± 200) and lung (sham, 297 ± 155; LR, 791 ± 331; MSC, 331 ± 172; MSC EV, 303 ± 88). Histopathologic injury in the small intestine and lung was also attenuated by MSCs and MSC EVs. In vitro, MSC CM but not MSC EVs attenuated the increased permeability among Caco-2 cell monolayers challenged with H2O2.

CONCLUSION

Mesenchymal stem cell EVs recapitulate the effects of MSCs in reducing vascular permeability and injury in the small intestine and lungs in vivo, suggesting MSC EVs may be a potential cell-free therapy targeting multi-organ dysfunction in HS/T. This is the first study to demonstrate that MSC EVs improve both gut and lung injury in an animal model of HS/T.

The gut brain in a dish: Murine primary enteric nervous system cell cultures

BACKGROUND

The enteric nervous system (ENS) is an extensive neural network embedded in the wall of the gastrointestinal tract that regulates digestive function and gastrointestinal homeostasis. The ENS consists of two main cell types; enteric neurons and enteric glial cells. In vitro techniques allow simplified investigation of ENS function, and different culture methods have been developed over the years helping to understand the role of ENS cells in health and disease.

PURPOSE

This review focuses on summarizing and comparing available culture protocols for the generation of primary ENS cells from adult mice, including dissection of intestinal segments, enzymatic digestions, surface coatings, and culture media. In addition, the potential of human ENS cultures is also discussed.

Digestive Enzyme Activity and Protein Degradation in Plasma of Heart Failure Patients

Introduction

Heart failure is associated with degradation of cell functions and extracellular matrix proteins, but the trigger mechanisms are uncertain. Our recent evidence shows that active digestive enzymes can leak out of the small intestine into the systemic circulation and cause cell dysfunctions and organ failure.

Methods

Accordingly, we investigated in morning fasting plasma of heart failure (HF) patients the presence of pancreatic trypsin, a major enzyme responsible for digestion.

Results

Western analysis shows that trypsin in plasma is significantly elevated in HF compared to matched controls and their concentrations correlate with the cardiac dysfunction biomarker BNP and inflammatory biomarkers CRP and TNF-α. The plasma trypsin levels in HF are accompanied by elevated pancreatic lipase concentrations. The trypsin has a significantly elevated activity as determined by substrate cleavage. Mass spectrometry shows that the number of plasma proteins in the HF patients is similar to controls while the number of peptides was increased about 20% in HF patients. The peptides are derived from extracellular and intracellular protein sources and exhibit cleavage sites by trypsin as well as other degrading proteases (data are available via ProteomeXchange with identifier PXD026332).

Connclusions

These results provide the first evidence that active digestive enzymes leak into the systemic circulation and may participate in myocardial cell dysfunctions and tissue destruction in HF patients.

Conclusions

These results provide the first evidence that active digestive enzymes leak into the systemic circulation and may participate in myocardial cell dysfunctions and tissue destruction in HF patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-021-00693-w.

The Gut-Lung Axis in Systemic Inflammation. Role of Mesenteric Lymph as a Conduit

Emerging evidence shows that after injury or infection, the mesenteric lymph acts as a conduit for gut-derived toxic factors to enter the blood circulation, causing systemic inflammation and acute lung injury. Neither the cellular and molecular identity of lymph factors nor their mechanisms of action have been well understood and thus have become a timely topic of investigation. This review will first provide a summary of background knowledge on gut barrier and mesenteric lymphatics, followed by a discussion focusing on the current understanding of potential injurious factors in the lymph and their mechanistic contributions to lung injury. We also examine lymph factors with antiinflammatory properties as well as the bidirectional nature of the gut-lung axis in inflammation.

Continuous enteral protease inhibition as a novel treatment for experimental trauma/hemorrhagic shock

PURPOSE

Trauma and hemorrhagic shock (T/HS) is a major cause of morbidity and mortality. Existing treatment options are largely limited to source control and fluid and blood repletion. Previously, we have shown that enteral protease inhibition improves outcomes in experimental models of T/HS by protecting the gut from malperfusion and ischemia. However, enteral protease inhibition was achieved invasively, by laparotomy and direct injection of tranexamic acid (TXA) into the small intestine. In this study, we tested a minimally invasive method of enteral protease inhibitor infusion in experimental T/HS that can be readily adapted for clinical use.

METHODS

Wistar rats were exsanguinated to a mean arterial blood pressure (MABP) of 40 mmHg, with laparotomy to induce trauma. Hypovolemia was maintained for 120 min and was followed by reperfusion of shed blood. Animals were monitored for an additional 120 min. A modified orogastric multi-lumen tube was developed to enable rapid enteral infusion of a protease inhibitor solution while simultaneously mitigating risk of reflux aspiration into the airways. The catheter was used to deliver TXA (T/HS + TXA) or vehicle (T/HS) continuously into the proximal small intestine, starting 20 min into the ischemic period.

RESULTS

Rats treated with enteral protease inhibition (T/HS + TXA) displayed improved outcomes compared to control animals (T/HS), including significantly improved MABP (p = 0.022) and lactate (p = 0.044). Mass spectrometry-based analysis of the plasma peptidome after T/HS indicated mitigation of systemic proteolysis in T/HS + TXA.

CONCLUSION

Minimally invasive, continuous enteral protease inhibitor delivery improves outcomes in T/HS and is readily translatable to the clinical arena.

The treatment of melioidosis: is there a role for repurposed drugs? A proposal and review

Introduction: Melioidosis is a significant health problem within endemic areas such as Southeast Asia and Northern Australia. The varied presentation of melioidosis and the intrinsic antibiotic resistance of Burkholderia pseudomallei, the causative organism, make melioidosis a difficult infection to manage. Often prolonged courses of antibiotic treatments are required with no guarantee of clinical success.Areas covered: B. pseudomallei is able to enter phagocytic cells, affect immune function, and replicate, via manipulation of the caspase system. An examination of this mechanism, and a look at other factors in the pathogenesis of melioidosis, shows that there are multiple potential points of therapeutic intervention, some of which may be complementary. These include the directed use of antimicrobial compounds, blocking virulence mechanisms, balancing or modulating cytokine responses, and ameliorating sepsis.Expert commentary: There may be therapeutic options derived from drugs in clinical use for unrelated conditions that may have benefit in melioidosis. Key compounds of interest primarily affect the disequilibrium of the cytokine response, and further preclinical work is needed to explore the utility of this approach and encourage the clinical research needed to bring these into beneficial use.

Effect of Montmorillonite powder on intestinal mucosal barrier in children with abdominal Henoch-Schonlein purpura: A randomized controlled study

BACKGROUND

Our previous studies found that intestinal barrier function has been changed in children with abdominal Henoch-Schonlein purpura (HSP). Montmorillonite has been shown to be protective for digestive tract mucosa.

OBJECTIVE

The present study aimed to investigate whether Montmorillonite powder could improve the intestinal mucosal barrier function in children with abdominal HSP.

METHODS

Using a randomized controlled study design, we compared plasma levels of diamine oxidase (DAO), D-lactate, and endotoxin in children with abdominal HSP before and after Montmorillonite powder treatment.

RESULTS

Among 28 patients in experimental group and 30 in control group, there was no significant difference in age, sex, height, weight, and course of disease between 2 groups (P > .05). Before treatment, there was no statistical difference in DAO, D-lactic acid, and endotoxin between experimental group and the control group (P > .05). However, significant differences were detected for DAO and D-lactate after treatment in comparison to before treatment in the Montmorillonite experimental group (P < .05). Such differences were not found in the control group (P > .05).

CONCLUSION

Montmorillonite powder is effective in the treatment of HSP via maintaining intestinal mucosal barrier function.

Proteolysis in septic shock patients: plasma peptidomic patterns are associated with mortality

BACKGROUND

Uncontrolled proteolysis contributes to cell injury and organ dysfunction in animal models of circulatory shock. We investigated in humans the relationship between septic shock, proteolysis, and outcome.

METHODS

Intensive care patients with septic shock (n=29) or sepsis (n=6) and non-hospitalised subjects (n=9) were recruited as part of the prospective observational trial 'ShockOmics' (ClinicalTrials.gov Identifier NCT02141607). A mass spectrometry-based approach was used to analyse the plasma peptidomes and the origin of circulating peptides from proteolysis in the enrolled subjects.

RESULTS

Evidence of systemic proteolysis was indicated by a larger number of circulating peptides in septic shock patients, compared with septic patients and non-hospitalised healthy subjects. The peptide count and abundance in the septic shock patients were greater in patients who died (n=6) than in survivors (n=23), suggesting an association between magnitude of proteolysis and outcome. In silico analysis of the peptide sequences and of the sites of cleavage on the proteins of origin indicated a predominant role for serine proteases, such as chymotrypsin, and matrix metalloproteases in causing the observed proteolytic degradation.

CONCLUSIONS

Systemic proteolysis is a novel fundamental pathological mechanism in septic shock. Plasma peptidomics is proposed as a new tool to monitor clinical trajectory in septic shock patients.

CLINICAL TRIAL REGISTRATION

NCT02141607.

Damage-associated molecular patterns in resuscitated hemorrhagic shock are mitigated by peritoneal fluid administration

Conventional resuscitation (CR) of hemorrhagic shock (HS), a significant cause of trauma mortality, is intravenous blood and fluids. CR restores central hemodynamics, but vital organ flow can drop, causing hypoperfusion, hypoxia, damage-associated molecular patterns (DAMPs), and remote organ dysfunction (i.e., lung). CR plus direct peritoneal resuscitation (DPR) prevents intestinal and hepatic hypoperfusion. We hypothesized that DPR prevents lung injury in HS/CR by altering DAMPs. Anesthetized male Sprague-Dawley rats were randomized to groups ( n = 8/group) in one of two sets: 1) sham (no HS, CR, or DPR), 2) HS/CR (HS = 40% mean arterial pressure (MAP) for 60 min, CR = shed blood + 2 volumes normal saline), or 3) HS/CR + DPR. The first set underwent whole lung blood flow by colorimetric microspheres. The second set underwent tissue collection for Luminex, ELISAs, and histopathology. Lipopolysaccharide (LPS) and DAMPs were measured in serum and/or lung, including cytokines, hyaluronic acid (HA), high-mobility group box 1 (HMGB1), Toll-like receptor 4 (TLR4), myeloid differentiation primary response 88 protein (MYD88), and TIR-domain-containing adapter-inducing interferon-β (TRIF). Statistics were by ANOVA and Tukey-Kramer test with a priori P < 0.05. HS/CR increased serum LPS, HA, HMGB1, and some cytokines [interleukin (IL)-1α, IL-1β, IL-6, and interferon-γ]. Lung TLR4 and MYD88 were increased but not TRIF compared with Shams. HS/CR + DPR decreased LPS, HA, cytokines, HMGB1, TLR4, and MYD88 levels but did not alter TRIF compared with HS/CR. The data suggest that gut-derived DAMPs can be modulated by adjunctive DPR to prevent activation of lung TLR-4-mediated processes. Also, DPR improved lung blood flow and reduced lung tissue injury. Adjunctive DPR in HS/CR potentially improves morbidity and mortality by downregulating the systemic DAMP response.

Mechanisms of I/R-Induced Endothelium-Dependent Vasodilator Dysfunction

Ischemia/reperfusion (I/R) induces leukocyte/endothelial cell adhesive interactions (LECA) in postcapillary venules and impaired endothelium-dependent, NO-mediated dilatory responses (EDD) in upstream arterioles. A large body of evidence has implicated reactive oxygen species, adherent leukocytes, and proteases in postischemic EDD dysfunction in conduit arteries. However, arterioles represent the major site for the regulation of vascular resistance but have received less attention with regard to the mechanisms underlying their reduced responsiveness to EDD stimuli in I/R. Even though leukocytes do not roll along, adhere to, or emigrate across arteriolar endothelium in postischemic intestine, recent work indicates that I/R-induced venular LECA is causally linked to EDD in arterioles. An emerging body of evidence suggests that I/R-induced EDD in arterioles occurs by a mechanism that is triggered by LECA in postcapillary venules and involves the formation of signals in the interstitium elicited by the proteolytic activity of emigrated leukocytes. This activity releases matricryptins from or exposes matricryptic sites in the extracellular matrix that interact with the integrin α_vβ₃ to induce mast cell chymase-dependent formation of angiotensin II (Ang II). Subsequent activation of NAD(P)H oxidase by Ang II leads to the formation of oxidants which inactivate NO and leads to eNOS uncoupling, resulting in arteriolar EDD dysfunction. This work establishes new links between LECA in postcapillary venules, signals generated in the interstitium by emigrated leukocytes, mast cell degranulation, and impaired EDD in upstream arterioles. These fundamentally important findings have enormous implications for our understanding of blood flow dysregulation in conditions characterized by I/R.

Enteral tranexamic acid attenuates vasopressor resistance and changes in α1-adrenergic receptor expression in hemorrhagic shock

BACKGROUND

Irreversible hemorrhagic shock is characterized by hyporesponsiveness to vasopressor and fluid therapy. Little is known, however, about the mechanisms that contribute to this phenomenon. Previous studies have shown that decreased intestinal perfusion in hemorrhagic shock leads to proteolytically mediated increases in gut permeability, with subsequent egress of vasoactive substances systemically. Maintenance of blood pressure is achieved in part by α1 receptor modulation, which may be affected by vasoactive factors; we thus hypothesized that decreases in hemodynamic stability and vasopressor response in shock can be prevented by enteral protease inhibition.

METHODS

Rats were exposed to experimental hemorrhagic shock (35 mm Hg mean arterial blood pressure for 2 hours, followed by reperfusion for 2 hours) and challenged with phenylephrine (2 μg/kg) at discrete intervals to measure vasopressor responsiveness. A second group of animals received enteral injections with the protease inhibitor tranexamic acid (TXA) (127 mM) along the small intestine and cecum 1 hour after induction of hemorrhagic shock.

RESULTS

Blood pressure response (duration and amplitude) to phenylephrine after reperfusion was significantly attenuated in animals subjected to hemorrhagic shock compared with baseline and control nonshocked animals and was restored to near baseline by enteral TXA. Arteries from shocked animals also displayed decreased α1 receptor density with restoration to baseline after enteral TXA treatment. In vitro, rat shock plasma decreased α1 receptor density in smooth muscle cells, which was also abrogated by enteral TXA treatment.

CONCLUSION

Results from this study demonstrate that experimental hemorrhagic shock leads to decreased response to the α1-selective agonist phenylephrine and decreased α1 receptor density via circulating shock factors. These changes are mitigated by enteral TXA with correspondingly improved hemodynamics. Proteolytic inhibition in the lumen of the small intestine improves hemodynamics in hemorrhagic shock, possibly by restoring α1 adrenergic functionality necessary to maintain systemic blood pressure and perfusion.

Intraluminal tranexamic acid inhibits intestinal sheddases and mitigates gut and lung injury and inflammation in a rodent model of hemorrhagic shock

BACKGROUND

Intravenous tranexamic acid (TXA) is an effective adjunct after hemorrhagic shock (HS) because of its antifibrinolytic properties. TXA is also a serine protease inhibitor, and recent laboratory data demonstrated that intraluminal TXA into the small bowel inhibited digestive proteases and protected the gut. A Disintegrin And Metalloproteinase 17 (ADAM-17) and tumor necrosis factor α (TNF-α) are effective sheddases of intestinal syndecan-1, which when shed, exposes the underlying intestinal epithelium to digestive proteases and subsequent systemic insult. We therefore hypothesized that intraluminal TXA as a serine protease inhibitor would reduce intestinal sheddases and syndecan-1 shedding, mitigating gut and distant organ (lung) damage.

METHODS

Mice underwent 90 minutes of HS to a mean arterial pressure of 35 ± 5 mm Hg followed by the intraluminal administration of TXA or vehicle. After 3 hours, the small intestine, lung, and blood were collected for analysis.

RESULTS

Intraluminal TXA significantly reduced gut and lung histopathologic injury and inflammation compared with HS alone. Gut, lung, and systemic ADAM-17 and TNF-α were significantly increased by HS but lessened by TXA. In addition, gut and lung syndecan-1 immunostaining were preserved and systemic shedding lessened after TXA. TXA reduced ADAM-17 and TNF-α, but not syndecan-1, in TXA-sham animals compared with sham vehicles.

CONCLUSION

Results of the present study demonstrate a beneficial effect of intraluminal TXA in the gut and lung after experimental HS in part because of the inhibition of the syndecan-1 shedding by ADAM-17 and TNF-α. Further studies are needed to determine if orally administered TXA could provide similar intestinal protection and thus be of potential benefit to patients with survivable hemorrhage at risk for organ injury. This is particularly relevant in patients or soldiers who may not have access to timely medical care.

Complement in Pancreatic Disease-Perpetrator or Savior?

The complement system is a major pillar of the humoral innate immune system. As a first line of defense against pathogens, it mediates early inflammatory response and links different branches of humoral and cellular immunity. Disorders affecting the exocrine pancreas, such as acute pancreatitis, potentially lead to a life-threatening systemic inflammatory response with aberrant activation of complement and coagulation cascades. Pancreatic proteases can activate key effectors of the complement system, which in turn drive local and systemic inflammation. Beyond that, the extent of pancreas–complement interaction covers complex pro- and anti-inflammatory mechanisms, which to this day remain to be fully elucidated. This review provides a comprehensive overview of the pathophysiological role of complement in diseases of the exocrine pancreas, based on existing experimental and clinical data. Participation of complement in acute and chronic pancreatitis is addressed, as well as its role in tumor immunology. Therapeutic strategies targeting complement in these diseases have long been proposed but have not yet arrived in the clinical setting.