The Diagnostic, Therapeutic and Prognostic Relevance of Neutrophil Extracellular Traps in Polytrauma

Neutrophil extracellular traps (NETs) represent a recently discovered polymorphonuclear leukocyte-associated ancient defence mechanism, and they have also been identified as part of polytrauma patients' sterile inflammatory response. This systematic review aimed to determine the clinical significance of NETs in polytrauma, focusing on potential prognostic, diagnostic and therapeutic relevance. The methodology covered all major databases and all study types, but was restricted to polytraumatised humans. Fourteen studies met the inclusion criteria, reporting on 1967 patients. Ten samples were taken from plasma and four from whole blood. There was no standardisation of methodology of NET detection among plasma studies; however, of all the papers that included a healthy control NET, proxies were increased. Polytrauma patients were consistently reported to have higher concentrations of NET markers in peripheral blood than those in healthy controls, but their diagnostic, therapeutic and prognostic utility is equivocal due to the diverse study population and methodology. After 20 years since the discovery of NETs, their natural history and potential clinical utility in polytrauma is undetermined, requiring further standardisation and research.

Chemotherapy-induced nanovaccines implement immunogenicity equivalence for improving cancer chemoimmunotherapy

Several chemoimmunotherapies have been approved by the FDA for the treatment of various cancers. Chemotherapy has the potential to improve the efficacy of immunotherapy by inducing immunogenic cell death (ICD) of tumor cells, promoting the release of tumor associated antigens (TAAs), tumor specific antigens (TSAs) and damage associated molecular patterns (DAMPs), and disrupting immunosuppressive microenvironments by tumor debulking. Unfortunately, systemic administration of chemotherapeutics carries side effects of blunting anti-cancer immune response through systemic immunosuppression, which deserves to be explored as an inner contradiction in chemoimmunotherapy. Here, we proposed the hypothesis of "immunogenicity equivalence" in chemoimmunotherapy that chemotherapeutics-induced immunogenic antigens and DAMPs in vitro that can subsequently be incorporated into nanovaccines, which will possess comparable immunostimulatory potential when compared to tumors treated with systemic chemotherapy in vivo. The proteomic analysis confirmed that our nanovaccines contained TAAs, TSAs and DAMPs. Improvement in treatment outcomes in tumor-bearing mice receiving anti-PD-1 and chemotherapy-induced nanovaccines was then observed. Furthermore, we demonstrated the feasibility of replacing long-term chemotherapy with nanovaccines in chemoimmunotherapy. Our nanovaccine strategy would be a general choice for formulating cancer vaccines in personalized medicine.

Potential of damage associated molecular patterns in synergising radiation and the immune response in oesophageal cancer

BACKGROUND

There is an intimate crosstalk between cancer formation, dissemination, treatment response and the host immune system, with inducing tumour cell death the ultimate therapeutic goal for most anti-cancer treatments. However, inducing a purposeful synergistic response between conventional therapies and the immune system remains evasive. The release of damage associated molecular patterns (DAMPs) is indicative of immunogenic cell death and propagation of established immune responses. However, there is a gap in the literature regarding the importance of DAMP expression in oesophageal adenocarcinoma (OAC) or by immune cells themselves.

AIM

To investigate the effects of conventional therapies on DAMP expression and to determine whether OAC is an immunogenic cancer.

METHODS

We investigated the levels of immunogenic cell death-associated DAMPs, calreticulin (CRT) and HMGB1 using an OAC isogenic model of radioresistance. DAMP expression was also assessed directly using ex vivo cancer patient T cells (n = 10) and within tumour biopsies (n = 9) both pre and post-treatment with clinically relevant chemo(radio)therapeutics.

RESULTS

Hypoxia in combination with nutrient deprivation significantly reduces DAMP expression by OAC cells in vitro. Significantly increased frequencies of T cell DAMP expression in OAC patients were observed following chemo(radio)therapy, which was significantly higher in tumour tissue compared with peripheral blood. Patients with high expression of HMGB1 had a significantly better tumour regression grade (TRG 1-2) compared to low expressors.

CONCLUSION

In conclusion, OAC expresses an immunogenic phenotype with two distinct subgroups of high and low DAMP expressors, which correlated with tumour regression grade and lymphatic invasion. It also identifies DAMPs namely CRT and HMGB1 as potential promising biomarkers in predicting good pathological responses to conventional chemo(radio)therapies currently used in the multimodal management of locally advanced disease.

Association of circulating histone H3 and high mobility group box 1 levels with postoperative prognostic indicators in intensive care unit patients: a single-center observational study

Objectives

Damage associated molecular patterns (DAMPs) levels are associated with sepsis severity and prognosis. Histone and high mobility group box 1 (HMGB1) levels are also potential indicators of prognosis. We investigated the relationship between serum histone H3 and HMGB1 levels and the illness severity score and prognosis in postoperative patients.

Methods

Postoperative serum histone H3 and HMGB1 levels in 39 intensive care unit (ICU) patients treated at our institution were measured. The correlation between peak histone H3 and HMGB1 levels in each patient and clinical data (age, sex, surgical time, length of ICU stay, and survival after ICU discharge), which also included the patients' illness severity score, was examined.

Results

Histone H3 but not HMGB1 levels were positively correlated with surgical time, the Sequential Organ Failure Assessment score, the Japanese Association for Acute Medicine acute phase disseminated intravascular coagulation diagnosis score, and the length of ICU stay. Both histone H3 and HMGB1 levels were negatively correlated with age. However, survival post-ICU discharge was not correlated with histone H3 or HMGB1 levels.

Conclusions

Histone H3 levels are correlated with severity scores and the length of ICU stay. Serum histone H3 and HMGB1 levels are elevated postoperatively. These DAMPs, however, are not prognostic indicators in postoperative ICU patients.

Pathophysiology in patients with polytrauma

The pathophysiology after polytrauma represents a complex network of interactions. While it was thought for a long time that the direct and indirect effects of hypoperfusion are most relevant due to the endothelial permeability changes, it was discovered that the innate immune response to trauma is equally important in modifying the organ response. Recent multi center studies provided a "genetic storm" theory, according to which certain neutrophil changes are activated at the time of injury. However, a second hit phenomenon can be induced by activation of certain molecules by direct organ injury, or pathogens (damage associated molecular patterns, DAMPS - pathogen associated molecular patterns, PAMPS). The interactions between the four pathogenetic cycles (of shock, coagulopathy, temperature loss and soft tissue injuries) and cross-talk between coagulation and inflammation have also been identified as important modifiers of the clinical status. In a similar fashion, overzealous surgeries and their associated soft tissue injury and blood loss can induce secondary worsening of the patient condition. Therefore, staged surgeries in certain indications represent an important alternative, to allow for performing a "safe definitive surgery" strategy for major fractures. The current review summarizes all these situations in a detailed fashion.

Role of caspase-8 and/or -9 as biomarkers that can distinguish the potential to cause toxic- and immune related-adverse event, for the progress of acetaminophen-induced liver injury

AIMS

Acetaminophen (APAP) overdose can cause acute liver failure. Although it is well known that APAP-induced liver injury (AILI) is caused by toxic mechanism, recently it is also reported to be immune related. However, the detail of the mechanism has been unclear. Therefore, elucidation of the pathophysiology is required.

MAIN METHODS

In AILI model rats (800 mg/kg), the levels of AST, ALT and Caspase (C)-3/-8/-9 levels were measured. In in vitro study using human hepatocyte cells (FLC-4) and THP-1 cells, APAP (1.0 mM) were added to FLC-4 and the cell viability, C-9, cytochrome c, mitochondria membrane potential, and glutathione levels of FLC-4 and inflammasome activation of THP-1 were evaluated.

KEY FINDINGS

In AILI model rats, the levels of AST and ALT were increased only at 12-24 h. C-3/-9 levels rose at 6-9 h, whereas C-8 level rose hours later, moreover, 24 h after; C-3/-8/-9 levels re-rose. In FLC-4 cells, cytochrome c was released from the mitochondria which is promoted by oxidative stress due to drug metabolism and C-9 was activated. Thus, AILI was caused mitochondrial damage by NAPQI as early reaction (first stage). In the next stage, inflammasomes of human antigen presenting cells, which released inflammatory cytokines were activated by damage-associated molecular patterns (DAMPs) released from damaged hepatocyte by APAP.

SIGNIFICANCE

It is confirmed that AILI includes immune related mechanism. Thereby, in case of N-acetylcysteine refractory, additional administration of steroid hormones should be effective and recommended as a novel strategy for AILI with immune related adverse event (irAE).

A live-cell assay for the real-time assessment of extracellular ATP levels

Extracellular ATP (eATP) is a potent damage associated molecular pattern (DAMP) molecule known to exert profound effects on the innate and adaptive immune responses. As such, it has become an important biomarker for studying means to pro-actively modulate inflammatory processes. Unfortunately, traditional methodologies employed for measuring eATP require cumbersome supernatant sampling, onerous time courses, or unnecessary duplication of effort. Here we describe a new reagent that is tolerable to test cells in extended exposures and enables a fully homogeneous assay method for real-time determinations of extracellular ATP levels. The reagent is introduced into assay plates containing cells at the time of stimulus introduction. The real-time feature of the format allows for sensitive, continuous accounting of eATP levels in the test model over at least 24 h. This work details our efforts to create and characterize this new reagent and to validate utility by demonstrating its use with multiple cell lines and chemically diverse eATP induction stimuli.

Association of hypoxia and mitochondrial damage associated molecular patterns in the pathogenesis of vein graft failure: a pilot study

Coronary artery bypass grafting (CABG) is the standard treatment modality in revascularization of the myocardium. However, the graft failure remains the major complication following CABG procedure. Involvement of mitochondrial damage-associated molecular patterns (mt-DAMPs) in the pathogenesis of vein-graft failure is largely unknown. Here, we investigated the expression of major protein-mt-DAMPs, cytochrome-C (Cyt-C), heat shock protein-60 (Hsp-60), mitochondrial transcription factor A (mtTFA), in the occluded graft and associated tissues, including distal left anterior descending (LAD), LAD adjacent to anastomosis, and left internal mammary artery (LIMA) in the microswine CABG model. The protein expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) was significantly decreased in the graft and LIMA, whereas the protein expression of hypoxia inducible factor-1 alpha (HIF-1α) and Cyt-C was decreased and that of mtTFA and Hsp60 was increased in all tissues compared to controls. There was no significant difference in the protein expression of citrate synthase, complex-1, and mitochondrial pyruvate dehydrogenase in the graft and associated tissues compared to control. Hypoxia in cultured smooth muscle cells (SMCs) significantly upregulated all mitochondrial biomarkers and mt-DAMPs compared to normoxia. The increased reactive oxygen species (ROS) content and compromised membrane integrity in the hypoxic SMCs correlated well with increased mt-DAMPs in the graft and associated tissues, suggesting a possible role of mt-DAMPs in the pathogenesis of graft failure. These findings suggest that the pathological signals elicited by mt-DAMPs could reveal targets for better therapeutic approaches and diagnostic strategies in the management of CABG graft failure.

Induction of immunogenic cell death of cancer cells through nanoparticle-mediated dual chemotherapy and photothermal therapy

The use of nanomedicines to induce immunogenic cell death is a new strategy that aims to increase tumor immunogenicity and thereby prime tumors for further immunotherapies. In this study, we developed a nanoparticle formulation for combinatory chemotherapy and photothermal therapy based only on materials previously used in FDA-approved products and investigated the effect of the combinatory therapy on the growth inhibition and induction of immunogenic cell death in human MDA-MB-231 breast cancer cells. The formulation consists of ~108-nm nanoparticles made of poly(lactic acid)-b-methoxy poly(ethylene glycol) which carry doxorubicin for chemotherapy and indocyanine green for photothermal therapy. A 0.3 mg/mL suspension of NPs increased the medium temperature up to 10 °C upon irradiation with an 808-nm diode laser. In vitro studies showed that combination of laser assisted indocyanine green-mediated photothermal therapy and doxorubicin-mediated chemotherapy effectively eradicated cancer cells and resulted in the highest level of damage-associated molecular pattern presentation (calreticulin, high mobility group box 1, and adenosine triphosphate) compared to the individual treatments alone. These results demonstrate that our nanoparticle-mediated combinatory approach led to the most intense immunogenic cell death when compared to individual chemotherapy or photothermal therapy, making it a potent option for future in vivo studies in combination with cancer immunotherapies.

Development of a novel minimally invasive technique to washout necrotic bone marrow content from epiphyseal bone: A preliminary cadaveric bone study

INTRODUCTION

Legg-Calvé-Perthes disease is a juvenile ischemic osteonecrosis which produces extensive necrotic cell debris and release of damage associated molecular patterns (DAMPs) in the femoral head. The necrotic bone environment induces a chronic inflammatory repair response with excessive bone resorption leading to deformity and early osteoarthritis. Currently there is no minimally invasive method to clear the necrotic materials from the bone to decrease the inflammatory burden of the necrotic environment and to improve the healing process.

HYPOTHESIS

We hypothesized that a novel minimally invasive two-needle saline washing technique would be effective to remove cell debris, proteins, and fat from the marrow space of porcine cadaveric humeral heads (HHs).

MATERIALS AND METHODS

Twenty-two HHs were subjected to three freeze-thaw cycles to simulate osteonecrosis prior to the wash procedure which consisted of placement of two 15-gauge intraosseous needles followed by incremental saline wash. After the washout procedure, the solutions were collected for measurements of turbidity, protein concentration, and cell count. The HHs were analyzed by optical scanning and histology.

RESULTS

The solution collected after each wash showed a significant decrease in the turbidity, cell count, and protein concentration (p<0.05). Histologic assessment showed significantly decreased cell debris and adipocytes in the washed group compared to the unwashed group (p<0.001).

DISCUSSION/CONCLUSION

The two-needle intraosseous wash technique effectively removed cell debris and proteins from the marrow space. The technique may be used to reduce the necrotic cell debris and DAMPs present in the necrotic bone.

LEVEL OF EVIDENCE

III, in vitro comparative study.

Prolonged Cardiopulmonary Bypass is Associated With Endothelial Glycocalyx Degradation

BACKGROUND

The endothelial glycocalyx (EG) is involved in critical regulatory mechanisms that maintain endothelial vascular integrity. We hypothesized that prolonged cardiopulmonary bypass (CPB) may be associated with EG degradation. We performed an analysis of soluble syndecan-1 levels in relation to duration of CPB, as well as factors associated with cell stress and damage, such as mitochondrial DNA (mtDNA) and inflammation.

METHODS

Blood samples from subjects undergoing cardiac surgery with CPB (n = 54) were obtained before and during surgery, 4-8 h and 24 h after completion of CPB, and on postoperative day 4. Flow cytometry was used to determine subpopulations of white blood cells. Plasma levels of mtDNA were determined using quantitative polymerase chain reaction and plasma content of shed syndecan-1 was measured. To determine whether syndecan-1 was signaling white blood cells, the effect of recombinant syndecan-1 on mobilization of neutrophils from bone marrow was tested in mice.

RESULTS

CPB is associated with increased mtDNA during surgery, increased syndecan-1 blood levels at 4-8 h, and increased white blood cell count at 4-8 h and 24 h. Correlation analysis revealed significant positive associations between time on CPB and syndecan-1 (r_s = 0.488, P < 0.001) and level of syndecan-1 and neutrophil count (r_s = 0.351, P = 0.038) at 4-8 h. Intravenous administration of recombinant syndecan-1 in mice resulted in a 2.5-fold increase in the number of circulating neutrophils, concurrent with decreased bone marrow neutrophil number.

CONCLUSIONS

Longer duration of CPB is associated with increased plasma levels of soluble syndecan-1, a signal for EG degradation, which can induce neutrophil egress from the bone marrow. Development of therapy targeting EG shedding may be beneficial in patients with prolonged CPB.

Overexpression of OsPUB41, a Rice E3 ubiquitin ligase induced by cell wall degrading enzymes, enhances immune responses in Rice and Arabidopsis

BACKGROUND

Cell wall degrading enzymes (CWDEs) induce plant immune responses and E3 ubiquitin ligases are known to play important roles in regulating plant defenses. Expression of the rice E3 ubiquitin ligase, OsPUB41, is enhanced upon treatment of leaves with Xanthomonas oryzae pv. oryzae (Xoo) secreted CWDEs such as Cellulase and Lipase/Esterase. However, it is not reported to have a role in elicitation of immune responses.

RESULTS

Expression of the rice E3 ubiquitin ligase, OsPUB41, is induced when rice leaves are treated with either CWDEs, pathogen associated molecular patterns (PAMPs), damage associated molecular patterns (DAMPs) or pathogens. Overexpression of OsPUB41 leads to induction of callose deposition, enhanced tolerance to Xoo and Rhizoctonia solani infection in rice and Arabidopsis respectively. In rice, transient overexpression of OsPUB41 leads to enhanced expression of PR genes and SA as well as JA biosynthetic and response genes. However, in Arabidopsis, ectopic expression of OsPUB41 results in upregulation of only JA biosynthetic and response genes. Transient overexpression of either of the two biochemically inactive mutants (OsPUB41C40A and OsPUB41V51R) of OsPUB41 in rice and stable transgenics in Arabidopsis ectopically expressing OsPUB41C40A failed to elicit immune responses. This indicates that the E3 ligase activity of OsPUB41 protein is essential for induction of plant defense responses.

CONCLUSION

The results presented here suggest that OsPUB41 is possibly involved in elicitation of CWDE triggered immune responses in rice.

The relationship between circulating mitochondrial DNA and inflammatory cytokines in patients with major depression

BACKGROUND

Although inflammatory cytokines are established biomarkers of mood disorders, their molecular mechanism is not known. We hypothesized that circulating mitochondrial DNA (mtDNA) contributes to inflammation and could be used as biomarkers. We investigated if circulating mtDNA level is associated with inflammatory cytokines and can be used as a biomarker of mood disorders.

METHODS

Plasma mtDNA concentration was measured with real-time quantitative PCR targeting two regions of the mtDNA and plasma levels of four cytokines (GM-CSF, IL-2, IL-4, and IL-6) were measured with a multiplex immunoassay method in 109 patients with major depressive disorder (MDD). The most significantly correlated cytokine was verified with an enzyme-linked immunosorbent assay (ELISA). The data from 28 patients with bipolar disorder (BD), 17 patients with schizophrenia (SZ), and 29 healthy controls were compared.

RESULTS

MtDNA levels showed a nominal positive correlation with GM-CSF, IL-2 and IL-4 in patients with MDD. The most significant correlation with IL-4 (ρ = 0.38, P < 0.00005) was verified with an ELISA (ρ = 0.19, P = 0.049). Unexpectedly, patients with MDD and BD showed significantly lower plasma mtDNA levels than controls. MtDNA levels were lower in the depressive state than in the euthymic state in patients with MDD. Patients with depression, bipolar disorder, and schizophrenia did not show significantly higher levels of these four cytokines than controls.

LIMITATIONS

There is a possibility that the patients in this study are different from previous studies in which increased cytokine levels were reported. MtDNA levels should be measured in patients showing elevated plasma cytokine levels. A larger sample is required to generalize the results.

CONCLUSIONS

The present findings coincide with our hypothesis that circulating mtDNA contributes to the inflammation in MDD. Further studies are needed to conclude whether plasma mtDNA would be a biomarker of mood disorders.

Immunological aspects of age-related diseases

The proportion of elderly people rises in the developed countries. The increased susceptibility of the elderly to infectious diseases is caused by immune dysfunction, especially T cell functional decline. Age-related hematopoietic stem cells deviate from lymphoid lineage to myeloid lineage. Thymus shrinks early in life, which is followed by the decline of naïve T cells. T-cell receptor repertoire diversity declines by aging, which is caused by cytomegalovirus-driven T cell clonal expansion. Functional decline of B cell induces antibody affinity declines by aging. Many effector functions including phagocytosis of myeloid cells are down regulated by aging. The studies of aging of myeloid cells have some controversial results. Although M1 macrophages have been shown to be replaced by anti-inflammatory (M2) macrophages by advanced age, many human studies showed that pro-inflammatory cytokines are elevated in older human. To solve this discrepancy here we divide age-related pathological changes into two categories. One is an aging of immune cell itself. Second is involvement of immune cells to age-related pathological changes. Cellular senescence and damaged cells in aged tissue recruit pro-inflammatory M1 macrophages, which produce pro-inflammatory cytokines and proceed to age-related diseases. Underlying biochemical and metabolic studies will open nutritional treatment.