Immune response to traumatic injury: harmony and discordance of immune system homeostasis

Neutrophil-to-lymphocyte ratio is elevated in acute hantavirus infection and correlates with markers of disease severity

Pathogenic Eurasian hantaviruses cause hemorrhagic fever with renal syndrome (HFRS), which is characterized by acute kidney injury. The clinical course shows a broad range of severity and is influenced by direct and immune-mediated effects. The neutrophil-to-lymphocyte ratio (NLR) is a marker of systemic inflammation and predicts severity and outcome in various diseases. Therefore, we examined the role of NLR in HFRS caused by hantavirus Puumala (PUUV) and its association with disease severity and kidney injury. We detected elevated NLR levels on admission (NLRadm: median 3.82, range 1.75-7.59), which increased during acute HFRS. Maximum NLR levels (NLRmax: median 4.19, range 1.75-13.16) were 2.38-fold higher compared to the reference NLR level of 1.76 in the general population. NLR levels on admission correlate with markers of severity (length of hospital stay, serum creatinine) but not with other markers of severity (leukocytes, platelets, C-reactive protein, lactate dehydrogenase, serum albumin, proteinuria). Interestingly, levels of nephrin, which is a specific marker of podocyte damage in kidney injury, are highest on admission and correlate with NLRmax, but not with NLRadm. Together, we observed a correlation between systemic inflammation and the severity of HFRS, but our results also revealed that podocyte damage precedes these inflammatory processes.

Quercetin counteracts monosodium glutamate to mitigate immunosuppression in the thymus and spleen via redox-guided cellular signaling

BACKGROUND

Chronic inflammation brought on by oxidative stress can result in several immunopathologies. Natural compounds with antioxidant characteristics, like quercetin, have shown effectiveness in reducing oxidative damage and regulating the immune response.

PURPOSE

The commonly used food additive monosodium glutamate (M) causes immunosuppression by disrupting redox equilibrium and inducing oxidative stress. The goal of this work is to examine the therapeutic potential of quercetin against immunotoxicity brought on by M, revealing the molecular route implicated in such immunopathology by targeting the thymus and spleen, to support the development of future anti-inflammatory and antioxidant therapies.

STUDY DESIGN AND METHODS

M-fed rats were employed as an immunotoxicity model and were supplemented with quercetin for four weeks. Hematological and biochemical parameters were measured; H&E staining, immunohistochemistry, flow cytometry, real-time quantitative PCR, and western blotting were performed.

RESULTS

Based on the findings, TLR4 was activated by M to cause oxidative stress-mediated inflammation, which was alleviated by the supplementation of quercetin by modulating redox homeostasis to neutralize free radicals and suppress the inflammatory response. To prevent M-induced inflammation, quercetin demonstrated anti-inflammatory functions by blocking NF-kB activation, lowering the production of pro-inflammatory cytokines, and increasing the release of anti-inflammatory cytokines. By normalizing lipid profiles and lowering the potential risk of immunological deficiency caused by M, quercetin also improves lipid metabolism. Additionally, it has shown potential for modifying insulin levels, suggesting a possible function in controlling M-induced alteration in glucose metabolism. The addition of quercetin to M enhanced the immune response by improving immunoglobulin levels and CD4/CD8 expression in the thymus and spleen. Additionally, quercetin inhibited apoptosis by controlling mitochondrial caspase-mediated cellular signaling, suggesting that it may be able to halt cell death in M-fed rats.

CONCLUSION

The results of this study first indicate that quercetin, via modulating redox-guided cellular signaling, has a promising role in reducing immune disturbances. This study illuminates the potential of quercetin as a safe, natural remedy for immunopathology caused by M, including thymic hypoplasia and/or splenomegaly, and paves the way for future anti-inflammatory and antioxidant supplements.

The impact of stapled compared to handsewn repair on anastomotic outcomes in trauma patients: a systematic review and meta-analysis

BACKGROUND

Approach to enteric anastomotic technique has been a subject of debate, with no clear consensus as to whether handsewn or stapled techniques are superior in trauma settings, which are influenced by unique perturbances to important processes such as immune function, coagulation, wound healing and response to infection. This systematic review and meta-analysis compares the risk of anastomotic complications in trauma patients with gastrointestinal injury requiring restoration of continuity with handsewn versus staples approaches.

METHODS

A comprehensive computer assisted search of electronic databases Medline, Embase and Cochrane Central was performed. Comparative studies evaluating stapled versus handsewn gastrointestinal anastomoses in trauma patients were included in this review. All anastomoses involving small intestine to small intestine, small to large intestine, and large intestine to large intestine were eligible. Anastomosis to the rectum was excluded. Outcomes evaluated were (1) anastomotic leak (AL) (2) a composite anastomotic complication (CAC) end point consisting of AL, enterocutaneous fistula (ECF) and deep abdominal abscess.

RESULTS

Eight studies involving 931 patients were included and of these patients, data from 790 patients were available for analysis. There was no significant difference identified for anastomotic leak between the two groups (OR = 0.77; 95% CI 0.24-2.45; P = 0.66). There was no significant improvement in composite anastomotic complication; defined as a composite of anastomotic leak, deep intra-abdominal abscess and intra-abdominal fistula, in the stapled anastomosis group (OR = 1.05; 95% CI 0.53-2.09; P = 0.90). Overall, there was limited evidence to suggest superiority with handsewn or stapled anastomosis for improving AL or CAC, however this was based on studies of moderate to high risk of bias with poor control for confounders.

DISCUSSION

This meta-analysis demonstrates no superiority improvement in anastomotic outcomes with handsewn or stapled repair. These findings may represent no effect in anastomotic outcome by technique for all situations. However, considering the paucity of information on potential confounders, perhaps there is a difference in outcome with overall technique or for specific subgroups that have not been described due to limited sample size and data on confounders. Currently, there is insufficient evidence to recommend an anastomotic technique in trauma.

Radiation-induced multi-organ injury

PURPOSE

Natural history studies have been informative in dissecting radiation injury, isolating its effects, and compartmentalizing injury based on the extent of exposure and the elapsed time post-irradiation. Although radiation injury models are useful for investigating the mechanism of action in isolated subsyndromes and development of medical countermeasures (MCMs), it is clear that ionizing radiation exposure leads to multi-organ injury (MOI).

METHODS

The Radiation and Nuclear Countermeasures Program within the National Institute of Allergy and Infectious Diseases partnered with the Biomedical Advanced Research and Development Authority to convene a virtual two-day meeting titled 'Radiation-Induced Multi-Organ Injury' on June 7-8, 2022. Invited subject matter experts presented their research findings in MOI, including study of mechanisms and possible MCMs to address complex radiation-induced injuries.

RESULTS

This workshop report summarizes key information from each presentation and discussion by the speakers and audience participants.

CONCLUSIONS

Understanding the mechanisms that lead to radiation-induced MOI is critical to advancing candidate MCMs that could mitigate the injury and reduce associated morbidity and mortality. The observation that some of these mechanisms associated with MOI include systemic injuries, such as inflammation and vascular damage, suggests that MCMs that address systemic pathways could be effective against multiple organ systems.

Systemic immune response of burns from the acute to chronic phase

Immune responses that occur following burn injury comprise a series of reactions that are activated in response to damaged autologous tissues, followed by removal of damaged tissues and foreign pathogens such as invading bacteria, and tissue repair. These immune responses are considered to be programmed in living organisms. Developments of modern medicine have led to the saving of burned patients who could not be cured previously; however, the programmed response is no longer able to keep up, and various problems have arisen. This paper describes the mechanism of immune response specific to burn injury and the emerging concept of persistent inflammation, immunosuppression, and catabolism syndrome.

Immune System, Inflammation and Autoantigens in Wet Age-Related Macular Degeneration: Pathological Significance and Therapeutic Importance

Wet age-related macular degeneration (wAMD) is a chronic inflammation-associated neurodegenerative disease affecting the posterior part of the eye in the aging population. Aging results in the reduced functionality of cells and tissues, including the cells of the retina. Initiators of a chronic inflammatory and pathologic state in wAMD may be a result of the accumulation of inevitable metabolic injuries associated with the maintenance of tissue homeostasis from a young age to over 50. Apart from this, risk factors like smoking, genetic predisposition, and failure to repair the injuries that occur, alongside attempts to rescue the hypoxic outer retina may also contribute to the pathogenesis. Aging of the immune system (immunosenescence) and a compromised outer blood retinal barrier (BRB) result in the exposure of the privileged milieu of the retina to the systemic immune system, further increasing the severity of the disease. When immune-privileged sites like the retina are under pathological stress, certain age- and disease-related conditions may necessitate assistance from cells distant from the resident ones to help restore the functionality of the tissue. As a necessary part of tissue repair, inflammation is a major response to disease and recruits immune cells to the site of damage. We suspect that the specific reparative inflammatory responses are controlled by an autoantigen-T cell-mediated mechanism, a process that may be hindered in wAMD.

Bioinformatics-Led Identification of Potential Biomarkers and Inflammatory Infiltrates in Burn Injury

Burn injury is a life-threatening disease with a poor prognosis. The immune change and underlying mechanisms remain largely unknown. Thus, this study aims to find potential biomarkers and analyze the immune infiltrates after burn injury. Gene expression data of burn patients were obtained from the Gene Expression Omnibus database. Key immune-related genes (IRGs) were screened by differential and least absolute shrinkage and selection operator (LASSO) regression analysis. Based on key IRGs, patients were divided into two clusters by consensus cluster analysis. Immune infiltration was analyzed by the single sample gene set enrichment analysis (GSEA) method and the immune score was calculated by the principal component analysis method. A nomogram model was constructed based on the calculated immune score and clinical features. Finally, the expression of screened key genes was validated by an external cohort and quantitative polymerase chain reaction experiment. Fifty-nine IRGs were differently expressed in burn patients. After LASSO regression analysis, 12 key genes remained, namely AZU1, OLR1, RNASE2, FGF13, NR1D2, NR2E1, TLR5, CAMP, DEFA4, PGLYRP1, CTSG, and CCR3. Then, patients were divided into two clusters. Immune infiltration analysis revealed that more immune cells were infiltrated and more pathways were activated in cluster A, in which patients showed high immune scores. Finally, a nomogram model was constructed and showed high accuracy and reliability. The expression pattern of 12 key genes in an external cohort and clinical samples was in accordance with the theoretical analysis results. In conclusion, this research elucidated the key role of immune response in burns and could be used as a guide for burn treatment.

Serum Selenium-Binding Protein 1 (SELENBP1) in Burn Injury: A Potential Biomarker of Disease Severity and Clinical Course

Oxidative stress, systemic inflammation, and metabolic derangements are hallmarks of burn pathophysiology. Severely burned patients are highly susceptible to infectious complications. Selenium-binding protein 1 (SELENBP1) modulates intracellular redox homeostasis, and elevated serum concentrations have been associated with adverse clinical outcomes in trauma patients. We hypothesized that serum SELENBP1 at hospital admission and during hospitalization may constitute a meaningful biomarker of disease severity and the clinical course in burn injury, with pulmonary infection as primary endpoint. To this end, we conducted a prospective cohort study that included 90 adult patients admitted to the Burn Center of the University Hospital Zurich, Switzerland. Patients were treated according to the local standard of care, with high-dose selenium supplementation during the first week. Serum SELENBP1 was determined at nine time-points up to six months postburn and the data were correlated to clinical parameters. SELENBP1 was initially elevated and rapidly declined within the first day. Baseline SELENBP1 levels correlated positively with the Abbreviated Burn Severity Index (ABSI) (R = 0.408; p < 0.0001). In multiple logistic regression, a higher ABSI was significantly associated with increased pulmonary infection risk (OR, 14.4; 95% CI, 3.2-88.8; p = 0.001). Similarly, baseline SELENBP1 levels constituted a novel but less accurate predictor of pulmonary infection risk (OR, 2.5; 95% CI, 0.7-8.9; p = 0.164). Further studies are needed to explore the additional value of serum SELENBP1 when stratifying patients with respect to the clinical course following major burns and, potentially, for monitoring therapeutic measures aimed at reducing tissue damage and oxidative stress.

Itaconate-producing neutrophils regulate local and systemic inflammation following trauma

Modulation of the immune response to initiate and halt the inflammatory process occurs both at the site of injury as well as systemically. Due to the evolving role of cellular metabolism in regulating cell fate and function, tendon injuries that undergo normal and aberrant repair were evaluated by metabolic profiling to determine its impact on healing outcomes. Metabolomics revealed an increasing abundance of the immunomodulatory metabolite itaconate within the injury site. Subsequent single-cell RNA-Seq and molecular and metabolomic validation identified a highly mature neutrophil subtype, not macrophages, as the primary producers of itaconate following trauma. These mature itaconate-producing neutrophils were highly inflammatory, producing cytokines that promote local injury fibrosis before cycling back to the bone marrow. In the bone marrow, itaconate was shown to alter hematopoiesis, skewing progenitor cells down myeloid lineages, thereby regulating systemic inflammation. Therapeutically, exogenous itaconate was found to reduce injury-site inflammation, promoting tenogenic differentiation and impairing aberrant vascularization with disease-ameliorating effects. These results present an intriguing role for cycling neutrophils as a sensor of inflammation induced by injury - potentially regulating immune cell production in the bone marrow through delivery of endogenously produced itaconate - and demonstrate a therapeutic potential for exogenous itaconate following tendon injury.

Early signaling of inflammation in patients following traumatic injury with accurately estimated time of injury by profiling C-reactive protein levels

BACKGROUND

Despite its widespread use, the precise dynamics of CRP response in clinical practice remain poorly defined. We employed a novel quadratic model to explore the time-course analysis of CRP values in trauma patients with known precise time of injury.

METHODS

Relevant data on all adult patients admitted to our hospital following traumatic incidents between January 1st 2010 to December 31, 2020 were retrospectively collected. Those with a documented time of injury and who underwent CRP evaluation within the first 24 h since injury were studied.

RESULTS

Based on the findings from our annual health check-up center, we established a reference upper normal CRP value of 12.99 mg/L. Within the first 7 h after injury, the CRP levels of 8-9% of the 1545 study patients exceeded the reference threshold. The proportion of patients with CRP levels > 12.99 mg/L increased to 18.5% at 8-9 h later and rose sharply to 91.6% at 22-24 h later. Our quadratic model yielded the equation: CRP = 5.122-0.528xTime + 0.139xTime 2. It accounted for > 40% of the variance in CRP levels (R2 = 42.4%).

CONCLUSIONS

Clear and prominent CRP elevations following atraumatic event are detected only 9-12 h following the insult. This novel finding has crucial implications for accurate CRP assessment of inflammatory responses to physical injuries.

Systemic inflammation induced from remote extremity trauma is a critical driver of secondary brain injury

Blast exposure, commonly experienced by military personnel, can cause devastating life-threatening polysystem trauma. Despite considerable research efforts, the impact of the systemic inflammatory response after major trauma on secondary brain injury-inflammation is largely unknown. The aim of this study was to identify markers underlying the susceptibility and early onset of neuroinflammation in three rat trauma models: (1) blast overpressure exposure (BOP), (2) complex extremity trauma (CET) involving femur fracture, crush injury, tourniquet-induced ischemia, and transfemoral amputation through the fracture site, and (3) BOP+CET. Six hours post-injury, intact brains were harvested and dissected to obtain biopsies from the prefrontal cortex, striatum, neocortex, hippocampus, amygdala, thalamus, hypothalamus, and cerebellum. Custom low-density microarray datasets were used to identify, interpret and visualize genes significant (p < 0.05 for differential expression [DEGs]; 86 neuroinflammation-associated) using a custom python-based computer program, principal component analysis, heatmaps and volcano plots. Gene set and pathway enrichment analyses of the DEGs was performed using R and STRING for protein-protein interaction (PPI) to identify and explore key genes and signaling networks. Transcript profiles were similar across all regions in naïve brains with similar expression levels involving neurotransmission and transcription functions and undetectable to low-levels of inflammation-related mediators. Trauma-induced neuroinflammation across all anatomical brain regions correlated with injury severity (BOP+CET > CET > BOP). The most pronounced differences in neuroinflammatory-neurodegenerative gene regulation were between blast-associated trauma (BOP, BOP+CET) and CET. Following BOP, there were few DEGs detected amongst all 8 brain regions, most were related to cytokines/chemokines and chemokine receptors, where PPI analysis revealed Il1b as a potential central hub gene. In contrast, CET led to a more excessive and diverse pro-neuroinflammatory reaction in which Il6 was identified as the central hub gene. Analysis of the of the BOP+CET dataset, revealed a more global heightened response (Cxcr2, Il1b, and Il6) as well as the expression of additional functional regulatory networks/hub genes (Ccl2, Ccl3, and Ccl4) which are known to play a critical role in the rapid recruitment and activation of immune cells via chemokine/cytokine signaling. These findings provide a foundation for discerning pathophysiological consequences of acute extremity injury and systemic inflammation following various forms of trauma in the brain.

A burns and COVID-19 shared stress responding gene network deciphers CD1C-CD141- DCs as the key cellular components in septic prognosis

Differential body responses to various stresses, infectious or noninfectious, govern clinical outcomes ranging from asymptoma to death. However, the common molecular and cellular nature of the stress responsome across different stimuli is not described. In this study, we compared the expression behaviors between burns and COVID-19 infection by choosing the transcriptome of peripheral blood from related patients as the analytic target since the blood cells reflect the systemic landscape of immune status. To this end, we identified an immune co-stimulator (CD86)-centered network, named stress-response core (SRC), which was robustly co-expressed in burns and COVID-19. The enhancement of SRC genes (SRCs) expression indicated favorable prognosis and less severity in both conditions. An independent whole blood single-cell RNA sequencing of COVID-19 patients demonstrated that the monocyte-dendritic cell (Mono-DC) wing was the major cellular source of SRC, among which the higher expression of the SRCs in the monocyte was associated with the asymptomatic COVID-19 patients, while the quantity-restricted and function-defected CD1C-CD141-DCs were recognized as the key signature which linked to bad consequences. Specifically, the proportion of the CD1C-CD141-DCs and their SRCs expression were step-wise reduced along with worse clinic conditions while the subcluster of CD1C-CD141-DCs from the critical COVID-19 patients was characterized of IFN signaling quiescence, high mitochondrial metabolism and immune-communication inactivation. Thus, our study identified an expression-synchronized and function-focused gene network in Mono-DC population whose expression status was prognosis-related and might serve as a new target of diagnosis and therapy.

Role of medicinal herbs and phytochemicals in post burn management

Burn management is a natural and distinctly programmed process involving overlapping phases of hemostasis, inflammation, proliferation and remodeling. Burn wound healing involves initiation of inflammation, re-epithelialization, granulation, neovascularization and wound contraction. Despite the availability of multiple preparations for management of burn wound, there is dire need for efficacious alternative agents. Current approaches for burn wound management include pharmaceutical agents and antibiotics. However, high cost of synthetic drugs and accelerated resistance to antibiotics is challenging for both developed and developing nations. Among alternative options, medicinal plants have been a biocompatible, safe and affordable source of preventive/curative approaches. Due to cultural acceptance and patient compliance, there has been a focus on the use of botanical drugs and phytochemicals for burn wound healing. Keeping in consideration of medicinal herbs and phytochemicals as suitable therapeutic/adjuvant agents for burn wound management, this review highlights therapeutic potential of 35 medicinal herbs and 10 phytochemicals. Among these, Elaeis guineensis, Ephedra ciliate and Terminalia avicennioides showed better burn wound healing potential with varied mechanisms such as modulation of TNF-alpha, inflammatory cytokines, nitric oxide, eicosanoids, ROS and leukocyte response. Phytochemicals (oleanolic acid, ursolic acid, kirenol) also showed promising role in burn wound management though various pathways involving such as down regulation of TNF-alpha, IL-6 and inflammatory mediators including plasma proteases and arachidonic acid metabolites. This review provides a pavement for therapeutic/adjuvant use of potential botanical drugs and novel druggable phyto-compounds to target skin burn injury with diverse mechanisms, affordability and safety profile.

NEW INSIGHTS INTO THE PATHOPHYSIOLOGY OF TRAUMA AND HEMORRHAGE

ABSTRACT

Circulatory shock from trauma and hemorrhage remains a clinical challenge with mortality still high within the first hours after impact. It represents a complex disease involving the impairment of a number of physiological systems and organs and the interaction of different pathological mechanisms. Multiple external and patient-specific factors may further modulate and complicate the clinical course. Recently, novel targets and models with complex multiscale interaction of data from different sources have been identified which offer new windows of opportunity. Future works needs to consider patient-specific conditions and outcomes to mount shock research onto the next higher level of precision and personalized medicine.

MACROPHAGE SWITCHING: POLARIZATION AND MOBILIZATION AFTER TRAUMA

ABSTRACT

Introduction: Trauma alters the immune response in numerous ways, affecting both the innate and adaptive responses. Macrophages play an important role in inflammation and wound healing following injury. We hypothesize that macrophages mobilize from the circulation to the site of injury and secondary sites after trauma, with a transition from proinflammatory (M1) shortly after trauma to anti-inflammatory (M2) at later time points. Methods: C57Bl6 mice (n = 6/group) underwent a polytrauma model using cardiac puncture/hemorrhage, pseudofemoral fracture, and liver crush injury. The animals were killed at several time points: uninjured, 24 h, and 7 days. Peripheral blood mononuclear cells, spleen, liver nonparenchymal cells, and lung were harvested, processed, and stained for flow cytometry. Macrophages were identified as CD68 + ; M1 macrophages were identified as iNOS + ; M2 macrophages as arginase 1 + . Results: We saw a slight presence of M1 macrophages at baseline in peripheral blood mononuclear cells (6.6%), with no significant change at 24 h and 7 days after polytrauma. In contrast, the spleen has a larger population of M1 macrophages at baseline (27.7%), with levels decreasing at 24 h and 7 days after trauma (20.6% and 12.6%, respectively). A similar trend is seen in the lung where at baseline 14.9% of CD68 + macrophages are M1, with subsequent continual decrease reaching 8.7% at 24 h and 4.4% at 7 days after polytrauma. M1 macrophages in the liver represent 14.3% of CD68 + population in the liver nonparenchymal cells at baseline. This percentage increases to 20.8% after trauma and decreases at 7 days after polytrauma (13.4%). There are few M2 macrophages in circulating peripheral blood mononuclear cells and in spleen at baseline and after trauma. The percentage of M2 macrophages in the lungs remains constant after trauma (7.2% at 24 h and 9.2% at 7 days). In contrast, a large proportion of M2 macrophages are seen in the liver at baseline (36.0%). This percentage trends upward and reaches 45.6% acutely after trauma and drops to 21.4% at 7 days. The phenotypic changes in macrophages seen in the lungs did not correlate with a functional change in the ability of the macrophages to perform oxidative burst, with an increase from 2.0% at baseline to 22.1% at 7 days after polytrauma ( P = 0.0258). Conclusion: Macrophage phenotypic changes after polytrauma are noted, especially with a decrease in the lung M1 phenotype and a short-term increase in the M2 phenotype in the liver. However, macrophage function as measured by oxidative burst increased over the time course of trauma, which may signify a change in subset polarization after injury not captured by the typical macrophage phenotypes.

Vitamin D3 and deconvoluting a rash

BACKGROUNDAdverse drug reactions are unpredictable immunologic events presenting frequent challenges to clinical management. Systemically administered cholecalciferol (vitamin D3) has immunomodulatory properties. In this randomized, double-blinded, placebo-controlled interventional trial of healthy human adults, we investigated the clinical and molecular immunomodulatory effects of a single high dose of oral vitamin D3 on an experimentally induced chemical rash.METHODSSkin inflammation was induced with topical nitrogen mustard (NM) in 28 participants. Participant-specific inflammatory responses to NM alone were characterized using clinical measures, serum studies, and skin tissue analysis over the next week. All participants underwent repeat NM exposure to the opposite arm and then received placebo or 200,000 IU cholecalciferol intervention. The complete rash reaction was followed by multi-omic analysis, clinical measures, and serum studies over 6 weeks.RESULTSCholecalciferol mitigated acute inflammation in all participants and achieved 6 weeks of durable responses. Integrative analysis of skin and blood identified an unexpected divergence in response severity to NM, corroborated by systemic neutrophilia and significant histopathologic and clinical differences. Multi-omic and pathway analyses revealed a 3-biomarker signature (CCL20, CCL2, CXCL8) unique to exaggerated responders that is suppressed by cholecalciferol and implicates IL-17 signaling involvement.CONCLUSIONHigh-dose systemic cholecalciferol may be an effective treatment for severe reactions to topical chemotherapy. Our findings have broad implications for cholecalciferol as an antiinflammatory intervention against the development of exaggerated immune responses.TRIAL REGISTRATIONclinicaltrials.gov (NCT02968446).FUNDINGNIH and National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS; grants U01AR064144, U01AR071168, P30 AR075049, U54 AR079795, and P30 AR039750 (CWRU)).

Patterns and Persistence of Perioperative Plasma and Cerebrospinal Fluid Neuroinflammatory Protein Biomarkers After Elective Orthopedic Surgery Using SOMAscan

BACKGROUND

The neuroinflammatory response to surgery can be characterized by peripheral acute plasma protein changes in blood, but corresponding, persisting alterations in cerebrospinal fluid (CSF) proteins remain mostly unknown. Using the SOMAscan assay, we define acute and longer-term proteome changes associated with surgery in plasma and CSF. We hypothesized that biological pathways identified by these proteins would be in the categories of neuroinflammation and neuronal function and define neuroinflammatory proteome changes associated with surgery in older patients.

METHODS

SOMAscan analyzed 1305 proteins in blood plasma (n = 14) and CSF (n = 15) samples from older patients enrolled in the Role of Inflammation after Surgery for Elders (RISE) study undergoing elective hip and knee replacement surgery with spinal anesthesia. Systems biology analysis identified biological pathways enriched among the surgery-associated differentially expressed proteins in plasma and CSF.

RESULTS

Comparison of postoperative day 1 (POD1) to preoperative (PREOP) plasma protein levels identified 343 proteins with postsurgical changes ( P < .05; absolute value of the fold change [|FC|] > 1.2). Comparing postoperative 1-month (PO1MO) plasma and CSF with PREOP identified 67 proteins in plasma and 79 proteins in CSF with altered levels ( P < .05; |FC| > 1.2). In plasma, 21 proteins, primarily linked to immune response and inflammation, were similarly changed at POD1 and PO1MO. Comparison of plasma to CSF at PO1MO identified 8 shared proteins. Comparison of plasma at POD1 to CSF at PO1MO identified a larger number, 15 proteins in common, most of which are regulated by interleukin-6 (IL-6) or transforming growth factor beta-1 (TGFB1) and linked to the inflammatory response. Of the 79 CSF PO1MO-specific proteins, many are involved in neuronal function and neuroinflammation.

CONCLUSIONS

SOMAscan can characterize both short- and long-term surgery-induced protein alterations in plasma and CSF. Acute plasma protein changes at POD1 parallel changes in PO1MO CSF and suggest 15 potential biomarkers for longer-term neuroinflammation that warrant further investigation.

The Efficacy of Honey Compared to Silver Sulfadiazine for Burn Wound Dressing in Superficial and Partial Thickness Burns—A Systematic Review and Meta-Analysis

Burn dressings play a vital role in protecting the patient from infection and aiding in the wound healing process. At present, the best burn wound dressing remains unknown. This study aimed to assess the efficacy of honey versus silver sulfadiazine dressing (SSD) for the treatment of superficial and partial thickness burns. We performed a systematic review and meta-analysis using the PubMed, MEDLINE and Embase databases to find relevant randomised control trials (RCTs) for inclusion. The outcomes measures included complete burn wound healing time, the proportion of wounds rendered sterile and subjective pain relief associated with the respective dressing type. This review was completed in line with PRISMA guidelines and has been registered with PROSPERO (Study ID: CRD42022337433). All studies in the English language that assessed honey versus SSD for patients with superficial or partial thickness burns were included. Quality and risk of bias assessments were performed using the Cochrane RoB2 tool. Seven studies were identified: totalling a population of 582 patients. From three studies, meta-analysis showed no significant difference in complete wound healing time (p = 0.06). Meta-analysis from five studies highlighted an overall significant difference favouring honey dressing in the proportion of wounds rendered sterile at day 7 post-injury (OR 10.80; 95% CI [5.76, 20.26]; p < 0.00001; I2 = 88%). We conclude that honey dressings may be as or more effective than SSD in the treatment of superficial and partial thickness burn injuries. However, due to the low quality of available studies in this field, further research is necessary to establish the optimum burn dressing. Ideally, this should be conducted in the form of prospective three-arm RCTs in accordance with the CONSORT statement.

Genetic and immune crosstalk between severe burns and blunt trauma: A study of transcriptomic data

Background: Severe burns and blunt trauma can lead to multiple organ dysfunction syndrome, the leading cause of death in intensive care units. In addition to infection, the degree of immune inflammatory response also affects prognosis. However, the characteristics and clinical relevance of the common mechanisms of these major diseases are still underexplored.

Methods: In the present study, we performed microarray data analysis to identify immune-related differentially expressed genes (DEGs) involved in both disease progression in burns and blunt trauma. Six analyses were subsequently performed, including gene enrichment analysis, protein‐protein interaction (PPI) network construction, immune cell infiltration analysis, core gene identification, co-expression network analysis, and clinical correlation analysis.

Results: A total of 117 common immune-related DEGs was selected for subsequent analyses. Functional analysis emphasizes the important role of Th17 cell differentiation, Th1 and Th2 cell differentiation, Cytokine-cytokine receptor interaction and T cell receptor signaling pathway in these two diseases. Finally, eight core DEGs were identified using cytoHubba, including CD8A, IL10, CCL5, CD28, LCK, CCL4, IL2RB, and STAT1. The correlation analysis showed that the identified core DEGs were more or less significantly associated with simultaneous dysregulation of immune cells in blunt trauma and sepsis patients. Of these, the downregulation of CD8A and CD28 had a worse prognosis.

Conclusion: Our analysis lays the groundwork for future studies to elucidate molecular mechanisms shared in burns and blunt trauma. The functional roles of identified core immune-related DEGs and dysregulated immune cell subsets warrant further in-depth study.

Immune dysfunction following severe trauma: A systems failure from the central nervous system to mitochondria

When a traumatic injury exceeds the body's internal tolerances, the innate immune and inflammatory systems are rapidly activated, and if not contained early, increase morbidity and mortality. Early deaths after hospital admission are mostly from central nervous system (CNS) trauma, hemorrhage and circulatory collapse (30%), and later deaths from hyperinflammation, immunosuppression, infection, sepsis, acute respiratory distress, and multiple organ failure (20%). The molecular drivers of secondary injury include damage associated molecular patterns (DAMPs), pathogen associated molecular patterns (PAMPs) and other immune-modifying agents that activate the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic stress response. Despite a number of drugs targeting specific anti-inflammatory and immune pathways showing promise in animal models, the majority have failed to translate. Reasons for failure include difficulty to replicate the heterogeneity of humans, poorly designed trials, inappropriate use of specific pathogen-free (SPF) animals, ignoring sex-specific differences, and the flawed practice of single-nodal targeting. Systems interconnectedness is a major overlooked factor. We argue that if the CNS is protected early after major trauma and control of cardiovascular function is maintained, the endothelial-glycocalyx will be protected, sufficient oxygen will be delivered, mitochondrial energetics will be maintained, inflammation will be resolved and immune dysfunction will be minimized. The current challenge is to develop new systems-based drugs that target the CNS coupling of whole-body function.

TACSTD2 upregulation is an early reaction to lung infection

TACSTD2 encodes a transmembrane glycoprotein Trop2 commonly overexpressed in carcinomas. While the Trop2 protein was discovered already in 1981 and first antibody–drug conjugate targeting Trop2 were recently approved for cancer therapy, the physiological role of Trop2 is still not fully understood. In this article, we show that TACSTD2/Trop2 expression is evolutionarily conserved in lungs of various vertebrates. By analysis of publicly available transcriptomic data we demonstrate that TACSTD2 level consistently increases in lungs infected with miscellaneous, but mainly viral pathogens. Single cell and subpopulation based transcriptomic data revealed that the major source of TACSTD2 transcript are lung epithelial cells and their progenitors and that TACSTD2 is induced directly in lung epithelial cells following infection. Increase in TACSTD2 expression may represent a mechanism to maintain/restore epithelial barrier function and contribute to regeneration process in infected/damaged lungs.

Key early proinflammatory signaling molecules encapsulated within circulating exosomes following traumatic injury

Background

Assessment of immune status in critically ill patients is often based on serial tracking of systemic cytokine levels and clinical laboratory values. Exosomes are extracellular vesicles that can be secreted and internalized by cells to transport important cellular cargo in the regulation of numerous physiological and pathological processes. Here, we characterize the early compartmentalization profile of key proinflammatory mediators in serum exosomes in the steady state and following trauma. Adult male Sprague-Dawley rats (91 including naïve) were divided into one of four traumatic injury model groups incorporating whole-body blast, fracture, soft-tissue crush injury, tourniquet-induced ischemia, and limb amputation. Serum was collected at 1, 3, 6, and 24 h, and 3- and 7-day post-injury. Electrochemiluminescence-based immunoassays for 9 key proinflammatory mediators in whole serum, isolated serum exosomes, and exosome depleted serum were analyzed and compared between naïve and injured rats. Serum clinical chemistry analysis was performed to determine pathological changes.

Results

In naïve animals, substantial amounts of IL-1β, IL-10, and TNF-α were encapsulated, IL-6 was completely encapsulated, and CXCL1 freely circulating. One hour after blast injury alone, levels of exosome encapsulated IFN-γ, IL-10, IL-6, IL-13, IL-4, and TNF-α increased, whereas freely circulating and membrane-associated levels remained undetectable or low. Rats with the most severe polytraumatic injuries with end organ complications had the earliest rise and most pronounced concentration of IL-1β, IL-10, TNF-α, and IL-6 across all serum compartments. Moreover, CXCL1 levels increased in relation to injury severity, but remained almost entirely freely circulating at all timepoints.

Conclusion

These findings highlight that conventional ELISA-based assessments, which detect only free circulating and exosome membrane-bound mediators, underestimate the full immunoinflammatory response to trauma. Inclusion of exosome encapsulated mediators may be a better, more accurate and clinically useful early strategy to identify, diagnose, and monitor patients at highest risk for post-traumatic inflammation-associated complications.

Efficacy of instillation of MB49 cells and thermoreversible polymeric gel in urothelial bladder carcinoma immunization

Background

Activating the immune system for therapeutic benefit has long been a goal in immunology, especially in cancer treatment, but the low immunogenicity of antitumor vaccines remains a limiting factor in the fight against malignant neoplasms. The increase in the immunogenicity of weak antigens using biodegradable polymers, such as chitosan, has been observed in the field of cancer immunotherapy. However, the effects of the vaccine using a combination of tumor cells and a thermoreversible delivery system based on chitosan in bladder cancer models, mainly using the intravesical route to stimulate the antitumor immune response, are unknown. We propose to evaluate the efficacy of a polymeric gel matrix (TPG) formed by poloxamer 407 and chitosan, associated with MB49 cells, as an intravesical antitumor vaccine using a C57BL/6 murine model of bladder urothelial carcinoma. The effectiveness of immunization was analyzed with the formation of three experimental groups: Control, TPG and TPG + MB49. In the vaccination phase, the TPG + MB49 group underwent a traumatic injury to the bladder wall with immediate intravesical instillation of the vaccine compound containing MB49 cells embedded in TPG. The TPG group was subjected to the same procedures using the compound containing the gel diluted in medium, and the control group using only the medium. After 21 days, the animals were challenged with tumor induction.

Results

In vitro tests showed loss of viability and inability to proliferate after exposure to TPG. In vivo tests showed that animals previously immunized with TPG + MB49 had higher cumulative survival, as well as significantly lower bladder weight and size in contrast to the other two groups that did not show a statistically different tumor evolution. In addition, the splenocytes of these animals also showed a higher rate of antitumor cytotoxicity in relation to the TPG and control groups.

Conclusions

We can conclude that MB49 cells embedded in a polymeric thermoreversible gel matrix with chitosan used in the form of an intravesical vaccine are able to stimulate the immune response and affect the development of the bladder tumor in an orthotopic and syngeneic C57BL/6 murine model.

Role of Inflammation in Traumatic Brain Injury-Associated Risk for Neuropsychiatric Disorders: State of the Evidence and Where Do We Go From Here

In the past decade, there has been an increasing awareness that traumatic brain injury (TBI) and concussion substantially increase the risk for developing psychiatric disorders. Even mild TBI increases the risk for depression and anxiety disorders such as posttraumatic stress disorder by two- to threefold, predisposing patients to further functional impairment. This strong epidemiological link supports examination of potential mechanisms driving neuropsychiatric symptom development after TBI. One potential mechanism for increased neuropsychiatric symptoms after TBI is via inflammatory processes, as central nervous system inflammation can last years after initial injury. There is emerging preliminary evidence that TBI patients with posttraumatic stress disorder or depression exhibit increased central and peripheral inflammatory markers compared with TBI patients without these comorbidities. Growing evidence has demonstrated that immune signaling in animals plays an integral role in depressive- and anxiety-like behaviors after severe stress or brain injury. In this review, we will 1) discuss current evidence for chronic inflammation after TBI in the development of neuropsychiatric symptoms, 2) highlight potential microglial activation and cytokine signaling contributions, and 3) discuss potential promise and pitfalls for immune-targeted interventions and biomarker strategies to identify and treat TBI patients with immune-related neuropsychiatric symptoms.

Quo Vadis Anesthesiologist? The Value Proposition of Future Anesthesiologists Lies in Preserving or Restoring Presurgical Health after Surgical Insult

This Special Issue of the Journal of Clinical Medicine is devoted to anesthesia and perioperative care [...].

Potential Immune Indicators for Predicting the Prognosis of COVID-19 and Trauma: Similarities and Disparities

Although cellular and molecular mediators of the immune system have the potential to be prognostic indicators of disease outcomes, temporal interference between diseases might affect the immune mediators, and make them difficult to predict disease complications. Today one of the most important challenges is predicting the prognosis of COVID-19 in the context of other inflammatory diseases such as traumatic injuries. Many diseases with inflammatory properties are usually polyphasic and the kinetics of inflammatory mediators in various inflammatory diseases might be different. To find the most appropriate evaluation time of immune mediators to accurately predict COVID-19 prognosis in the trauma environment, researchers must investigate and compare cellular and molecular alterations based on their kinetics after the start of COVID-19 symptoms and traumatic injuries. The current review aimed to investigate the similarities and differences of common inflammatory mediators (C-reactive protein, procalcitonin, ferritin, and serum amyloid A), cytokine/chemokine levels (IFNs, IL-1, IL-6, TNF-α, IL-10, and IL-4), and immune cell subtypes (neutrophil, monocyte, Th1, Th2, Th17, Treg and CTL) based on the kinetics between patients with COVID-19 and trauma. The mediators may help us to accurately predict the severity of COVID-19 complications and follow up subsequent clinical interventions. These findings could potentially help in a better understanding of COVID-19 and trauma pathogenesis.

HMGB1 Inhibition to Ameliorate Organ Failure and Increase Survival in Trauma

Several preclinical and clinical reports have demonstrated that levels of circulating high mobility group box 1 protein (HMGB1) are increased early after trauma and are associated with systemic inflammation and clinical outcomes. However, the mechanisms of the interaction between HMGB1 and inflammatory mediators that lead to the development of remote organ damage after trauma remain obscure. HMGB1 and inflammatory mediators were analyzed in plasma from 54 combat casualties, collected on admission to a military hospital in Iraq, and at 8 and 24 h after admission. In total, 45 (83%) of these patients had traumatic brain injury (TBI). Nine healthy volunteers were enrolled as controls. HMGB1 plasma levels were significantly increased in the first 8 h after admission, and were found to be associated with systemic inflammatory responses, injury severity score, and presence of TBI. These data provided the rationale for designing experiments in rats subjected to blast injury and hemorrhage, to explore the effect of HMGB1 inhibition by CX-01 (2-O, 3-O desulfated heparin). Animals were cannulated, then recovered for 5–7 days before blast injury in a shock tube and volume-controlled hemorrhage. Blast injury and hemorrhage induced an early increase in HMGB1 plasma levels along with severe tissue damage and high mortality. CX-01 inhibited systemic HMGB1 activity, decreased local and systemic inflammatory responses, significantly reduced tissue and organ damage, and tended to increase survival. These data suggest that CX-01 has potential as an adjuvant treatment for traumatic hemorrhage.

Changes of pituitary adenylate cyclase activating polypeptide (PACAP) level in polytrauma patients in the early post-traumatic period

In polytrauma patients who survive the primary insult, the imbalance between the pro- and anti-inflammatory processes seems to be responsible for life-threatening complications such as sepsis or multiple organ dysfunction syndrome. Measurement of C-reactive protein (CRP) and procalcitonin (PCT) is a standard way for differentiating between infectious (bacterial) and non-infectious inflammation. Monitoring of immune cell functions, like leukocyte anti-sedimentation rate (LAR) can also be useful to diagnose infectious complications. Pituitary adenylate cyclase activating polypeptide (PACAP) is a neuropeptide with well-known immunomodulatory and anti-inflammatory effects. The aim of our study was to determine the changes of PACAP38 levels in polytrauma patients in the early post-traumatic period in intensive care unit and analyse possible correlation of its level with conventional (CRP, PCT) and unconventional (LAR) laboratory parameters. Twenty polytrauma patients were enrolled. Blood samples were taken daily for five days. We observed significant correlation between PACAP38 and CRP levels on day 4 and 5 as well as between PACAP38 and LAR levels all of the days. This could be due to the anti-inflammatory and cytoprotective functions of PACAP38 as part of an endogenous response to the trauma induced systemic inflammatory response syndrome. These significant correlations could have clinical importance in monitoring the dynamic balance of pro- and anti-inflammatory processes in case of polytraumatic patients.

The journey of SARS-CoV-2 in human hosts: a review of immune responses, immunosuppression, and their consequences

Coronavirus disease 2019 (COVID-19) is a highly infectious viral disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Laboratory findings from a significant number of patients with COVID-19 indicate the occurrence of leukocytopenia, specifically lymphocytopenia. Moreover, infected patients can experience contrasting outcomes depending on lymphocytopenia status. Patients with resolved lymphocytopenia are more likely to recover, whereas critically ill patients with signs of unresolved lymphocytopenia develop severe complications, sometimes culminating in death. Why immunodepression manifests in patients with COVID-19 remains unclear. Therefore, the evaluation of clinical symptoms and laboratory findings from infected patients is critical for understanding the disease course and its consequences. In this review, we take a logical approach to unravel the reasons for immunodepression in patients with COVID-19. Following the footprints of the virus within host tissues, from entry to exit, we extrapolate the mechanisms underlying the phenomenon of immunodepression.

Towards in silico Models of the Inflammatory Response in Bone Fracture Healing

In silico modeling is a powerful strategy to investigate the biological events occurring at tissue, cellular and subcellular level during bone fracture healing. However, most current models do not consider the impact of the inflammatory response on the later stages of bone repair. Indeed, as initiator of the healing process, this early phase can alter the regenerative outcome: if the inflammatory response is too strongly down- or upregulated, the fracture can result in a non-union. This review covers the fundamental information on fracture healing, in silico modeling and experimental validation. It starts with a description of the biology of fracture healing, paying particular attention to the inflammatory phase and its cellular and subcellular components. We then discuss the current state-of-the-art regarding in silico models of the immune response in different tissues as well as the bone regeneration process at the later stages of fracture healing. Combining the aforementioned biological and computational state-of-the-art, continuous, discrete and hybrid modeling technologies are discussed in light of their suitability to capture adequately the multiscale course of the inflammatory phase and its overall role in the healing outcome. Both in the establishment of models as in their validation step, experimental data is required. Hence, this review provides an overview of the different in vitro and in vivo set-ups that can be used to quantify cell- and tissue-scale properties and provide necessary input for model credibility assessment. In conclusion, this review aims to provide hands-on guidance for scientists interested in building in silico models as an additional tool to investigate the critical role of the inflammatory phase in bone regeneration.

Burns and patients infected with COVID-19 at a burn treatment centre in Brazil: a series of case-reports

BACKGROUND

In December 2019, in Wuhan, China, several cases of viral pneumonia, caused by a new type of coronavirus (SARS-CoV-2, a disease that became known as COVID-19) emerged. Being an alarming situation, many resources were directed to fight this pandemic. However, other diseases and conditions, such as burn injuries, continued to occur in this period, thus creating multiple challenges.

METHOD

Four patients with COVID-19 treated in a reference burn treatment centre from the Northeast region of Brazil, in the city of Fortaleza were analysed between April to June 2020.

RESULTS

All patients were admitted in the service without signs of COVID-19 infection; however the symptoms appeared a few days after hospitalisation. The most common symptom was fever, especially when it occurred in only one spike. Patients who evolved to an unfavourable outcome had comorbidities prior to the infection and burn injury. In addition to this, these two patients had a worsening of their renal function, in contrast to the other two patients that received hospital discharge.

CONCLUSION

The burned patient is a complex one that requires the health professional's attention and special care. This became even more evident during the period of the COVID-19 pandemic. Thus, the patients' changes and symptoms must be cautiously analysed, their diagnosis should not be delayed and it must be made under standardised protocols accordingly with the socio-economic and cultural realities of each service.

TMT-based quantitative proteomic analysis reveals the spleen regulatory network of dexamethasone-induced immune suppression in chicks

Stress-induced immunosuppression is one of the most widespread problems in the poultry industry. Understanding the molecular regulatory mechanism of immunosuppression induced by stress in the chicken spleen would provide a scientific foundation for the prevention of stress reactions and antistress molecular breeding in poultry. To assess the protein expression profile of spleen tissue in a stress-included immunosuppression model, we performed a TMT-based proteomic analysis of chicken spleen tissue in a Dex-induced immunosuppression model (group C) and a control group (group A). We identified 590 differentially abundant proteins (DAPs) in chicken spleen tissue. These DAPs were significantly enriched in the following functional categories: ECM-receptor interaction, DNA replication, p53 signaling pathway, PI3K-Akt signaling pathway and NF-kappa B signaling pathway. Integrative analysis of the proteome and our previous transcriptome data revealed 62 DAPs showing correlations with the expression of their encoding mRNAs. Complementary proteome- and transcriptome-level analyses revealed a complex molecular network of stress-included immunosuppression. DPP4 and ALDH1A3 were the most significantly upregulated DAPs. GBP and OASL were identified as important nodes in the network related to stress-induced immunosuppression. The candidate genes identified in this study may be useful for the marker-based breeding of new chicken varieties with reduced stress levels. SIGNIFICANCE: This study provides a large amount of new information about the spleen proteome of the Dex-induced immunosuppression in chicks, as well as the correlation of transcriptome and proteome. Analysis of this resource has enabled us to examine mechanism of protein and transcript diversification, which expands the understanding of the complexity of the mechanism of stress-induced immunosuppression.

Unusual cause of gastrointestinal bleeding in an 84-year-old woman: a miraculous survival from an aortoduodenal fistula repair

An 84-year-old woman presented acutely with dizziness, fatigue and a total of 800 mL of fresh per rectum (PR) bleeding. The significant history of abdominal aortic aneurysm repair 5 years ago included multiple episodes of endovascular leak around the stent associated with abscess of left psoas major, left abdominal wall abscess with sinus formation, appendicitis with abscess formation, and acute pancreatic and chronic cholecystitis with multiple gallstones in the 7 months prior to this presentation. During the preceding 7 months, the patient was stabilised with an intravenous proton pump inhibitor, blood transfusions and Intensive Care Unit (ICU) management for the assumed diagnosis of stress ulcers over multiple hospital admissions. Imaging with CT scan of the abdomen made the more accurate diagnosis of acute gastrointestinal haemorrhage caused by a fistula between the distal duodenum and aorta, which was later surgically confirmed. Removal of infected stents and axillobifemoral bypass were performed with a successful recovery.

Impact of Age on Plasma Inflammatory Biomarkers in the 6 Months Following Mild Traumatic Brain Injury

OBJECTIVE

To compare plasma inflammatory biomarker concentrations to 6 months in young and older adults with and without mild traumatic brain injury (TBI).

SETTING

Level 1 trauma center.

PARTICIPANTS

Younger (21-54 years) and older (55+) adults diagnosed with mild TBI along with age-/sex-matched noninjured controls (n = 313).

DESIGN

Prospective cohort study.

MAIN MEASURES

Multiplex assays were used to quantify concentrations of selected plasma inflammatory markers at day 0, months 1 and 6.

RESULTS

Persistent aging-related differences were found between control groups in concentrations of 4 cytokines up to 6 months. At day 0, interleukin-6 (IL-6), IL-8, and fractalkine were higher in the older TBI compared with older control as well as the younger TBI groups, while IL-10 was higher in older TBI compared with controls. At month 1, significantly higher concentrations of IL-8, fractalkine, and tumor necrosis factor-α (TNF-α) were seen. At 6 months postinjury, significantly higher concentrations of IL-6 and IL-8 were seen, while a lower concentration of IL-7 was found in older versus younger TBI groups.

CONCLUSION

The neuroinflammatory signature that accompanies mild TBI in older adults differs from that of younger adults. The differences seen are notable for their roles in neutrophil attraction (IL-8), neuronal-microglial-immune cell interactions (fractalkine), and chronic inflammation (IL-6).

Gut Microbial Changes and their Contribution to Post-Burn Pathology

ABSTRACT

Burn injuries are a common form of traumatic injury that leads to significant morbidity and mortality worldwide. Burn injuries are characterized by inflammatory processes and alterations in numerous organ systems and functions. Recently, it has become apparent that the gastrointestinal bacterial microbiome is a key component of regulating the immune response and recovery from burn and can also contribute to significant detrimental sequelae after injury, such as sepsis and multiple organ failure. Microbial dysbiosis has been linked to multiple disease states; however, its role in exacerbating acute traumatic injuries, such as burn, is poorly understood. In this article, we review studies that document changes in the intestinal microbiome after burn injury, assess the implications in post-burn pathogenesis, and the potential for further discovery and research.

Expression of angiogenesis-related proteins in bone marrow mesenchymal stem cells induced by osteoprotegerin during osteogenic differentiation in rats

This study aimed to discuss the expression of angiogenesis-related proteins in bone marrow mesenchymal stem cells (BMSCs) induced by osteoprotegerin (OGP) during osteogenic differentiation in rats, and to analyze the effect of fracture healing inflammatory factor TNF-ɑ on the osteogenic differentiation of BMSCs of rats. BMSCs isolated and cultured from the third generation rats were taken as the research object. According to the addition amount of OGP, BMSCs were divided into control group, OGP (10^-7 mol/L) group, OGP (10^-8 mol/L) group, and OGP (10^-9 mol/L) group. The cell growth and morphological characteristics of each group were observed by inverted phase contrast microscope, the cell proliferation rate was measured by MTT method, angiogenesis-related markers (platelet growth factor (VEGF), cingulate protein 5 (Fbln5), and angiogenin-like protein 4 (Angptl4)) were quantitatively detected by Western blot, and the effect of TNF-ɑ on osteogenic differentiation was detected by CCK. Compared with the control group, MTT results showed that the value-added rate of cells in the OGP (10^-8 mol/L) group reached the maximum at 9 days (P < 0.05). The ALP activity in osteoblasts in the OGP (10^-8 mol/L) group reached the maximum at 9 days (P < 0.01). The OGP (10^-8 mol/L) group had the highest expression of vascular regeneration proteins (VEGF, Fbln5, and Angptl4) (P < 0.05). CCK analysis showed that the TNF-ɑ (1.0 ng/mL) group showed a significant increase in absorbance compared with the control group on 6 days (P < 0.05), and the OD value of the TNF-ɑ (10 ng/mL) group decreased at all time points (P < 0.05). Overall, 10^-8 mol/L OGP can induce the proliferation and osteogenic differentiation of MSCs, and promote the expression of angiogenesis-related proteins (VEGF, Fbln5, and Angptl4) during osteogenic differentiation. Besides, 1.0 ng/mL of TNF-ɑ can also promote osteogenesis differentiation of BMSCs in the short term.

The Effects of Tacrolimus on Tissue-Specific, Protein-Level Inflammatory Networks in Vascularized Composite Allotransplantation

Systems-level insights into inflammatory events after vascularized composite allotransplantation (VCA) are critical to the success of immunomodulatory strategies of these complex procedures. To date, the effects of tacrolimus (TAC) immunosuppression on inflammatory networks in VCA, such as in acute rejection (AR), have not been investigated. We used a systems biology approach to elucidate the effects of tacrolimus on dynamic networks and principal drivers of systemic inflammation in the context of dynamic tissue-specific immune responses following VCA. Lewis (LEW) rat recipients received orthotopic hind limb VCA from fully major histocompatibility complex-mismatched Brown Norway (BN) donors or matched LEW donors. Group 1 (syngeneic controls) received LEW limbs without TAC, and Group 2 (treatment group) received BN limbs with TAC. Time-dependent changes in 27 inflammatory mediators were analyzed in skin, muscle, and peripheral blood using Principal Component Analysis (PCA), Dynamic Bayesian Network (DyBN) inference, and Dynamic Network Analysis (DyNA) to define principal characteristics, central nodes, and putative feedback structures of systemic inflammation. Analyses were repeated on skin + muscle data to construct a "Virtual VCA", and in skin + muscle + peripheral blood data to construct a "Virtual Animal." PCA, DyBN, and DyNA results from individual tissues suggested important roles for leptin, VEGF, various chemokines, the NLRP3 inflammasome (IL-1β, IL-18), and IL-6 after TAC treatment. The chemokines MCP-1, MIP-1α; and IP-10 were associated with AR in controls. Statistical analysis suggested that 24/27 inflammatory mediators were altered significantly between control and TAC-treated rats in peripheral blood, skin, and/or muscle over time. "Virtual VCA" and "Virtual Animal" analyses implicated the skin as a key control point of dynamic inflammatory networks, whose connectivity/complexity over time exhibited a U-shaped trajectory and was mirrored in the systemic circulation. Our study defines the effects of TAC on complex spatiotemporal evolution of dynamic inflammation networks in VCA. We also demonstrate the potential utility of computational analyses to elucidate nonlinear, cross-tissue interactions. These approaches may help define precision medicine approaches to better personalize TAC immunosuppression in VCA recipients.

Alarming Cargo: The Role of Exosomes in Trauma-Induced Inflammation

Severe polytraumatic injury initiates a robust immune response. Broad immune dysfunction in patients with such injuries has been well-documented; however, early biomarkers of immune dysfunction post-injury, which are critical for comprehensive intervention and can predict the clinical course of patients, have not been reported. Current circulating markers such as IL-6 and IL-10 are broad, non-specific, and lag behind the clinical course of patients. General blockade of the inflammatory response is detrimental to patients, as a certain degree of regulated inflammation is critical and necessary following trauma. Exosomes, small membrane-bound extracellular vesicles, found in a variety of biofluids, carry within them a complex functional cargo, comprised of coding and non-coding RNAs, proteins, and metabolites. Composition of circulating exosomal cargo is modulated by changes in the intra- and extracellular microenvironment, thereby serving as a homeostasis sensor. With its extensively documented involvement in immune regulation in multiple pathologies, study of exosomal cargo in polytrauma patients can provide critical insights on trauma-specific, temporal immune dysregulation, with tremendous potential to serve as unique biomarkers and therapeutic targets for timely and precise intervention.

Preclinical models for studying immune responses to traumatic injury

Traumatic injury initiates a large and complex immune response in the minutes after the initial insult, comprising of simultaneous pro- and anti-inflammatory responses. In patients that survive the initial injury, these immune responses are believed to contribute towards complications such as the development of sepsis and multiple organ dysfunction syndrome. These post-traumatic complications affect a significant proportion of patients and are a major contributing factor for poor outcomes and an increased burden on healthcare systems. Therefore, understanding the immune responses to trauma is crucial for improving patient outcomes through the development of novel therapeutics and refining resuscitation strategies. In order to do this, preclinical animal models must mimic human immune responses as much as possible, and as such, we need to understand the constraints of each species in the context of trauma. A number of species have been used in this field; however, these models are limited by their genetic background and their capacity for recapitulating human immune function. This review provides a brief overview of the immune response in critically injured human patients and discusses the most commonly used species for modelling trauma, focusing on how their immune response to serious injury and haemorrhage compares to that of humans.

Different experimental multiple trauma models induce comparable inflammation and organ injury

Multiple injuries appear to be a decisive factor for experimental polytrauma. Therefore, our aim was to compare the inflammatory response and organ damage of five different monotrauma with three multiple trauma models. For this, mice were randomly assigned to 10 groups: Healthy control (Ctrl), Sham, hemorrhagic shock (HS), thoracic trauma (TxT), osteotomy with external fixation (Fx), bilateral soft tissue trauma (bsTT) or laparotomy (Lap); polytrauma I (PT I, TxT + HS + Fx), PT II (TxT + HS + Fx + Lap) and one multi-trauma group (MT, TxT + HS + bsTT + Lap). The inflammatory response and organ damage were quantified at 6 h by analyses of IL-6, IL-1β, IL-10, CXCL1, SAA1, HMGB1 and organ injury. Systemic IL-6 increased in all mono and multiple trauma groups, while CXCL1 increased only in HS, PT I, PT II and MT vs. control. Local inflammatory response was most prominent in HS, PT I, PT II and MT in the liver. Infiltration of inflammatory cells into lung and liver was significant in all multiple trauma groups vs. controls. Hepatic and pulmonary injury was prominent in HS, PT I, PT II and MT groups. These experimental multiple trauma models closely mimic the early post-traumatic inflammatory response in human. Though, the choice of read-out parameters is very important for therapeutic immune modulatory approaches.

Emerging Infectious Diseases and Antimicrobial Resistance (EIDAR)

Introduction

The Infectious Disease Clinical Research Program’s (IDCRP) Emerging Infectious Diseases and Antimicrobial Resistance (EIDAR) Research Area is a Department of Defense (DoD) clinical research capability that is responsive and adaptive to emerging infectious disease (EID) threats to US military readiness. Among active-duty and other Military Health System (MHS) beneficiaries, EIDAR research is largely focused on evaluating the incidence, risk factors, and acute- and long-term health effects of military-relevant EIDs, especially those caused by high-consequence pathogens or are responsible for outbreaks among US military populations. The EIDAR efforts also address Force Health Protection concerns associated with antimicrobial resistance and antimicrobial stewardship practices within the MHS.

Methods

The EIDAR studies utilize the approach of: (1) Preparing for emergent conditions to systematically collect clinical specimens and data and conduct clinical trials to assist the military with a scientifically appropriate response; and (2) Evaluating burden of emergent military-relevant infectious diseases and assessing risks for exposure and development of post-infectious complications and overall impact on military readiness.

Results

In response to the Ebola virus epidemic in West Africa, the IDCRP partnered with the National Institutes of Health in developing a multicenter, randomized safety and efficacy study of investigational therapeutics in Ebola patients. Subsequently, the EIDAR team developed a protocol to serve as a contingency plan (EpICC-EID) to allow clinical research activities to occur during future outbreaks of viral hemorrhagic fever and severe acute respiratory infections among MHS patients. The EIDAR portfolio recently expanded to include studies to understand exposure risks and impact on military readiness for a diversity of EIDs, such as seroincidence of non-Lyme disease borreliosis and Coccidioides fungal infections among high-risk military populations. The team also launched a new prospective study in response to the recent Zika epidemic to conduct surveillance for Zika and other related viruses among MHS beneficiaries in Puerto Rico. Another new study will prospectively follow U.S. Marines via an online health assessment survey to assess long-term health effects following the largest DoD Shiga Toxin-Producing Escherichia coli outbreak at the U.S. Marine Corps Recruit Depot-San Diego. In cooperation with the Trauma-Related Infections Research Area, the EIDAR Research Area is also involved with the Multidrug-Resistant and Virulent Organisms Trauma Infections Initiative, which is a collaborative effort across DoD laboratories to characterize bacterial and fungal isolates infecting combat-related extremity wounds and link lab findings to clinical outcomes. Furthermore, the EIDAR team has developed an Antimicrobial Resistance and Stewardship Collaborative Clinical Research Consortium, comprised of Infectious Disease and Pharmacy specialists.

Conclusions

The EIDAR Research Area is responsive to military-relevant infectious disease threats that are also frequently global public health concerns. Several new EIDAR efforts are underway that will provide Combatant Command Surgeons, Infectious Diseases Service Chiefs, and other Force Health Protection stakeholders with epidemiological information to mitigate the impact of EIDs and antimicrobial resistance on the health of U.S. military service members and their dependents.

Transcriptomic Analysis of Spleen Revealed Mechanism of Dexamethasone-Induced Immune Suppression in Chicks

Stress-induced immunosuppression is a common problem in the poultry industry, but the specific mechanism of its effect on the immune function of chicken has not been clarified. In this study, 7-day-old Gushi cocks were selected as subjects, and a stress-induced immunosuppression model was successfully established via daily injection of 2.0 mg/kg (body weight) dexamethasone. We characterized the spleen transcriptome in the control (B_S) and model (D_S) groups, and 515 significant differentially expressed genes (SDEGs) (Fragments Per Kilobase of transcript sequence per Millions base pairs sequenced (FPKM) > 1, adjusted p-value (padj) < 0.05 and Fold change (|FC|) ≥ 2) were identified. The cytokine-cytokine receptor interaction signaling pathway was identified as being highly activated during stress-induced immunosuppression, including the following SDEGs-CXCL13L2, CSF3R, CSF2RB, CCR9, CCR10, IL1R1, IL8L1, IL8L2, GHR, KIT, OSMR, TNFRSF13B, TNFSF13B, and TGFBR2L. At the same time, immune-related SDEGs including CCR9, CCR10, DMB1, TNFRSF13B, TNFRSF13C and TNFSF13B were significantly enriched in the intestinal immune network for the IgA production signaling pathway. The SDEG protein-protein interaction module analysis showed that CXCR5, CCR8L, CCR9, CCR10, IL8L2, IL8L1, TNFSF13B, TNFRSF13B and TNFRSF13C may play an important role in stress-induced immunosuppression. These findings provide a background for further research on stress-induced immunosuppression. Thus, we can better understand the molecular genetic mechanism of chicken stress-induced immunosuppression.

Burn injury

Burn injuries are under-appreciated injuries that are associated with substantial morbidity and mortality. Burn injuries, particularly severe burns, are accompanied by an immune and inflammatory response, metabolic changes and distributive shock that can be challenging to manage and can lead to multiple organ failure. Of great importance is that the injury affects not only the physical health, but also the mental health and quality of life of the patient. Accordingly, patients with burn injury cannot be considered recovered when the wounds have healed; instead, burn injury leads to long-term profound alterations that must be addressed to optimize quality of life. Burn care providers are, therefore, faced with a plethora of challenges including acute and critical care management, long-term care and rehabilitation. The aim of this Primer is not only to give an overview and update about burn care, but also to raise awareness of the ongoing challenges and stigmata associated with burn injuries.

Crosstalk between T Helper Cell Subsets and Their Roles in Immunopathogenesis and Outcome of Polytrauma Patients

Purpose

One of the leading causes of morbidity and early-age mortality across the globe is trauma. It disrupts immune system homeostasis and intensely affects the innate and adaptive immune responses, predisposing patients to posttrauma complications and poor outcomes. Most of the studies on posttrauma cellular immune response have been centered on the T helper-1-T helper-2 imbalances after trauma. This study was conducted to understand the role of circulating novel T helper cells in the acute posttraumatic period and clinical outcome of trauma patients.

Materials and methods

Signature cytokines and transcription factors of circulating Th (T helper)-9, Th-17, Th-22, and regulatory T helper cells were studied using flowcytometry along with serum biomarkers in 49 patients with polytraumatic injuries admitted to a tertiary care hospital. The patients were followed up until their outcome. The results were correlated with their clinical outcomes.

Results

In patients who died, higher nTreg, iTreg, Tr1 (early-phase), and higher IRF4+Th-9, IL17+ Th-17, and RORγT+ Th-17 (mid-phase) were seen. However, by the late phase, only RORγT+ Th-17 remained higher. Serum IL-6 and PCT were found to be consistently higher. In survivors, higher Th-3 (early phase), Th-22 (mid-phase), and IRF4+Th-9, IL17+ Th-17, nTreg, Th-3 (late phase) were observed to have played a protective role. Serum IL-2, IL-4, IL-17A and IL-22 were significantly higher in survivors.

Conclusion

Different T helper subsets were observed to be playing pathogenic and protective roles in different phases of trauma and could be used for early prognostication and make way for noninvasive management of critically injured trauma patients by immunomodulation.

How to cite this article

Khurana S, Bhardwaj N, Kumar S, Sagar S, Pal R, Soni KD, et al. Crosstalk between T Helper Cell Subsets and Their Roles in Immunopathogenesis and Outcome of Polytrauma Patients. Indian J Crit Care Med 2020;24(11):1037–1044.

Impact of oral resuscitation on circulating and splenic leukocytes after burns

BACKGROUND

Hemodynamic aberrations after severe burns are treated with aggressive intravenous (IV) fluid resuscitation however, oral resuscitation has been proposed in resource poor scenarios. Previously we have shown that animals receiving oral fluid following burns were able to recover kidney function. However, immune function such as circulating and splenic immune cell populations after oral or intravenous fluid administration was not examined. Herein, we perform a follow up analysis of splenic tissue and plasma from the previous animal study to examine the splenic response following these resuscitation strategies after burn injury.

METHODS

Eighteen anesthetized Yorkshire swine receiving 40%TBSA contact burns were randomized to receive either: (1) no fluids (Fluid Restricted; negative control), (2) 70 mL/kg/d Oral Rehydration Salt solution (Oral), or (3) 2 mL/kg/%TBSA/d of lactated Ringer's solution IV. Blood was drawn for blood cell analysis, and CT scans were performed before and 48 h post-burn, at which point spleens were harvested for histological, Western blot, and RT-PCR analyses.

RESULTS

Splenic artery diameter decreased by -0.97 ± 0.14 mm in fluid-restricted animals, while IV led to an increase of 0.68 ± 0.30 mm. No significant differences were detected in white and red pulp. IV fluids reduced the population of splenic monocytes (CD163; P = 0.001) and neutrophils (MPO protein; P = 0.13), as well as cytokines IL-8 (P = 0.003), IFN-γ (P = 0.11) and TNFα (P = 0.05). Additionally, withholding IV fluids consistently decreased the expression of FoxP3, CCR6, and IL17β in spleen, suggesting a shift in T-cell phenotype with IV resuscitation.

CONCLUSIONS

The route of fluid administration has a minor influence on the changes in circulating and splenic leukocytes post-burn in the acute phase. Further research is needed to help guide resuscitation approaches using immunologic markers of splenic function following burns.

Functional immune monitoring in severely injured patients-A pilot study

After severe trauma, the resulting excessive inflammatory response is countered by compensatory anti-inflammatory mechanisms. The systemic inflammatory response to trauma enhanced by inappropriately timed surgical second hits may be detrimental for the patient. On the other hand, overwhelming anti-inflammatory mechanisms may put patients at increased risk from secondary local and systemic infections. The ensuing sepsis and organ dysfunction due to immune dysregulation remain the leading causes of death after injury. To date, there are no clinically applicable techniques to monitor the pro-/anti-inflammatory immune status of the patients and the remaining ability to react to microbial stimuli. Therefore, in the present study, we used a highly standardized and easy-to-use system to draw peripheral whole blood from polytraumatized patients (ISS ≥ 32, n = 7) and to challenge it with bacterial lipopolysaccharide. Secreted cytokines were compared with those in samples from healthy volunteers. We observed a significant decrease in the release of monocyte-derived mediators. Surprisingly, we detected stable or even increased concentrations of cytokines related to T cell maturation and function. For clinical practicability, we reduced the incubation time before supernatants were collected. Even after an abbreviated stimulation period, a stable release of almost all analysed parameters in patient blood could be detected. In conclusion, the data are indicative of a clinically well-applicable approach to monitor the immune status in severely injured patients in a short time. This may be used to optimize the timing of necessary surgical interventions to avoid a boost of proinflammation and reduce risk of secondary infections.

Damage-associated molecular patterns in trauma

In 1994, the “danger model” argued that adaptive immune responses are driven rather by molecules released upon tissue damage than by the recognition of “strange” molecules. Thus, an alternative to the “self versus non-self recognition model” has been provided. The model, which suggests that the immune system discriminates dangerous from safe molecules, has established the basis for the future designation of damage-associated molecular patterns (DAMPs), a term that was coined by Walter G. Land, Seong, and Matzinger. The pathological importance of DAMPs is barely somewhere else evident as in the posttraumatic or post-surgical inflammation and regeneration. Since DAMPs have been identified to trigger specific immune responses and inflammation, which is not necessarily detrimental but also regenerative, it still remains difficult to describe their “friend or foe” role in the posttraumatic immunogenicity and healing process. DAMPs can be used as biomarkers to indicate and/or to monitor a disease or injury severity, but they also may serve as clinically applicable parameters for optimized indication of the timing for, i.e., secondary surgeries. While experimental studies allow the detection of these biomarkers on different levels including cellular, tissue, and circulatory milieu, this is not always easily transferable to the human situation. Thus, in this review, we focus on the recent literature dealing with the pathophysiological importance of DAMPs after traumatic injury. Since dysregulated inflammation in traumatized patients always implies disturbed resolution of inflammation, so-called model of suppressing/inhibiting inducible DAMPs (SAMPs) will be very briefly introduced. Thus, an update on this topic in the field of trauma will be provided.

A nationwide fluidics biobank of polytraumatized patients: implemented by the Network "Trauma Research" (NTF) as an expansion to the TraumaRegister DGU® of the German Trauma Society (DGU)

To decrypt the complexity of the posttraumatic immune responses and to potentially identify novel research pathways for exploration, large-scale multi-center projects including not only in vivo and in vitro modeling, but also temporal sample and material collection along with clinical data capture from multiply injured patients is of utmost importance. To meet this gap, a nationwide biobank for fluidic samples from polytraumatized patients was initiated in 2013 by the task force Network “Trauma Research” (Netzwerk Traumaforschung, NTF) of the German Trauma Society (Deutsche Gesellschaft für Unfallchirurgie e.V., DGU). The NTF-Biobank completes the clinical NTF-Biobank Database and complements the TR-DGU with temporal biological samples from multiply injured patients. The concept behind the idea of the NTF-Biobank was to create a robust interface for meaningful innovative basic, translational and clinical research. For the first time, an integrated platform to prospectively evaluate and monitor candidate biomarkers and/or potential therapeutic targets in biological specimens of quality-controlled and documented patients is introduced, allowing reduction in variability of measurements with high impact due to its large sample size. Thus, the project was introduced to systemically evaluate and monitor multiply injured patients for their (patho-)physiological sequalae together with their clinical treatment strategies applied for overall outcome improval.

Inflammasomes in Tissue Damages and Immune Disorders After Trauma

Trauma remains a leading cause of death worldwide. Hemorrhagic shock and direct injury to vital organs are responsible for early mortality whereas most delayed deaths are secondary to complex pathophysiological processes. These processes result from imbalanced systemic reactions to the multiple aggressions associated with trauma. Trauma results in the uncontrolled local and systemic release of endogenous mediators acting as danger signals [damage-associated molecular patterns (DAMPs)]. Their recognition by the innate immune system triggers a pro-inflammatory immune response paradoxically associated with concomitant immunosuppression. These responses, ranging in intensity from inappropriate to overwhelming, promote the propagation of injuries to remote organs, leading to multiple organ failure and death. Some of the numerous DAMPs released after trauma trigger the assembly of intracellular multiprotein complexes named inflammasomes. Once activated by a ligand, inflammasomes lead to the activation of a caspase. Activated caspases allow the release of mature forms of interleukin-1β and interleukin-18 and trigger a specific pro-inflammatory cell death termed pyroptosis. Accumulating data suggest that inflammasomes, mainly NLRP3, NLRP1, and AIM2, are involved in the generation of tissue damage and immune dysfunction after trauma. Following trauma-induced DAMP(s) recognition, inflammasomes participate in multiple ways in the development of exaggerated systemic and organ-specific inflammatory response, contributing to organ damage. Inflammasomes are involved in the innate responses to traumatic brain injury and contribute to the development of acute respiratory distress syndrome. Inflammasomes may also play a role in post-trauma immunosuppression mediated by dysregulated monocyte functions. Characterizing the involvement of inflammasomes in the pathogenesis of post-trauma syndrome is a key issue as they may be potential therapeutic targets. This review summarizes the current knowledge on the roles of inflammasomes in trauma.

Danger signals in trauma

This review summarizes a short list of currently discussed trauma-induced danger-associated molecular patterns (DAMP). Due to the bivalent character and often pleiotropic effects of a DAMP, it is difficult to describe its "friend or foe" role in post-traumatic inflammation and regeneration, both systemically as well locally in tissues. DAMP can be used as biomarkers to indicate or monitor disease or injury severity, but also may serve as clinically applicable parameters for better indication and timing of surgery. Due to the inflammatory processes at the local tissue level or the systemic level, the precise role of DAMP is not always clear to define. While in vitro and experimental studies allow for the detection of these biomarkers at the different levels of an organism-cellular, tissue, circulation-this is not always easily transferable to the human setting. Increased knowledge exploring the dual role of DAMP after trauma, and concentrating on their nuclear functions, transcriptional targets, release mechanisms, cellular sources, multiple functions, their interactions and potential therapeutic targeting is warranted.