An ongoing search for potential targets and therapies for lethal sepsis

Sepsis, which refers to a systemic inflammatory response syndrome resulting from a microbial infection, represents the leading cause of death in intensive care units. The pathogenesis of sepsis remains poorly understood although it is attributable to dysregulated immune responses orchestrated by innate immune cells that sequentially release early(e.g., tumor necrosis factor(TNF), interleukin-1(IL-1), and interferon-γ(IFN-γ) and late(e.g., high mobility group box 1(HMGB1)) pro-inflammatory mediators. As a ubiquitous nuclear protein, HMGB1 can be passively released from pathologically damaged cells, thereby converging infection and injury on commonly dysregulated inflammatory responses. We review evidence that supports extracellular HMGB1 as a late mediator of inflammatory diseases and discuss the potential of several Chinese herbal components as HMGB1-targeting therapies. We propose that it is important to develop strategies for specifically attenuating injury-elicited inflammatory responses without compromising the infection-mediated innate immunity for the clinical management of sepsis and other inflammatory diseases.

Expert consensus on the monitoring and treatment of sepsis-induced immunosuppression

Emerged evidence has indicated that immunosuppression is involved in the occurrence and development of sepsis.To provide clinical practice recommendations on the immune function in sepsis,an expert consensus focusing on the monitoring and treatment of sepsis-induced immunosuppression was developed.Literature related to the immune monitoring and treatment of sepsis were retrieved from PubMed,Web of Science,and Chinese National Knowledge Infrastructure to design items and expert opinions were collected through an online questionnaire.Then,the Delphi method was used to form consensus opinions,and RAND appropriateness method was developed to provide consistency evaluation and recommendation levels for consensus opinions.This consensus achieved satisfactory results through two rounds of questionnaire survey,with 2 statements rated as perfect consistency,13 as very good consistency,and 9 as good consistency.After summarizing the results,a total of 14 strong recommended opinions,8 weak recommended opinions and 2 non-recommended opinions were produced.Finally,a face-to-face discussion of the consensus opinions was performed through an online meeting,and all judges unanimously agreed on the content of this consensus.In summary,this expert consensus provides a preliminary guidance for the monitoring and treatment of immunosuppression in patients with sepsis.

Bioelectronic medicine in modulation of cortical spreading depolarization and beyond

Bioelectronic interventions,specifically trigeminal nerve st imulat ion(TNS),have attracted considerable attention in conditions where cortical spreading depolarizations(CSDs)accompanied by compromised cerebral perfusion may exacerbate neurological damage.While pharmacological interventions have demonstrated initial potential in addressing CSDs,a standardized treatment approach has not yet been established.The objective of this perspective is to explore emerging bioelectronic methodologies for addressing CSDs,particularly emphasizing TNS,and to underscore TNS’s capacity to enhance neurovascular coupling and cerebral perfusion.

Lung epithelial cell-derived IL-25 negatively regulates LPS-induced exosome release from macrophages

Background: Acute lung injury(ALI) is a major component of multiple organ dysfunction syndrome(MODS) following pulmonary and systemic infection. Alveolar macrophages(AMφ) are at the center of ALI pathogenesis. Emerging evidence has shown that cell-cell interactions in the lungs play an important regulatory role in the development of acute lung inflammation. However, the underneath mechanisms remain poorly addressed. In this study, we explore a novel function of lung epithelial cells(LEPCs) in regulating the release of exosomes from AMφ following LPS stimulation.Methods: For the in vivo experiments, C57 BL/6 wildtype(WT) mice were treated with lipopolysaccharide(LPS)(2 mg/kg) in 0.2 ml of saline via intratracheal aerosol administration. Bronchoalveolar lavage fluid was collected at 0–24 h after LPS treatment, and exosomes derived from AMφ were measured. For the in vitro studies, LEPCs and bone marrowderived Mφ(BMDM) were isolated from WT or TLR4-/-mice and were then cocultured in the Transwell? system. After coculture for 0–24 h, the BMDM and supernatant were harvested for the measurement of exosomes and cytokines.Results: We demonstrate that LPS induces macrophages(Mφ) to release exosomes, which are then internalized by neighboring Mφ to promote TNF-α expression. The secreted interleukin(IL)-25 from LEPCs downregulates Rab27 a and Rab27 b expression in Mφ, resulting in suppressed exosome release and thereby attenuating exosome-induced TNF-α expression and secretion.Conclusion: These findings reveal a previously unidentified crosstalk pathway between LEPCs and Mφ that negatively regulates the inflammatory responses of Mφ to LPS. Modulating IL-25 signaling and targeting exosome release may present a new therapeutic strategy for the treatment of ALI.

Requirement for cyclin D3 in germinal center formation and function

Germinal centers （GC） of secondary lymphoid tissues are critical to mounting a high-affinity humoral immune response. B cells within the GC undergo rapid clonal expansion and selection while diversifying their antibody genes. Although it is generally believed that GC B cells employ a unique proliferative program to accommodate these processes, little is known about how the GC-associated cell cycle is orchestrated. The D-type cyclins constitute an important component of the cell cycle engine that enables the cells to respond to physiological changes. Cell type- and developmental stage-specific roles of D-type cyclins have been described but the cyclin D requirement during GC reaction has not been addressed. In this study, we report that cyclin D3 is largely dispensable for proliferation and Ig class switching of in vitro activated B cells. In contrast, GC development in Ccnd3^-/- mice is markedly impaired, as is the T cell-dependent antibody response. Within the GC, although both switched and unswitched B cells are affected by cyclin D3 inactivation, the IgM^- pool is more severely reduced. Interestingly, despite a compensatory increase in cyclln D2 expression, a significant number of Ccnd3^-/- GC B cells accumulate in quiescent GO state. Lastly, although cyclin D3 inactivation did not disrupt BCL6 expression in GC B cells, it completely blocked the GC promoting effect of BCL6 overexpression, suggesting that cyclin D3 acts downstream of BCL6 to regulate GC formation. This is the first demonstration that cyclin D3 plays an important and unique role at the GC stage of B cell development.

Metabolic syndrome and liver disease in the era of bariatric surgery: What you need to know!

Metabolic syndrome(MS)is defined as the constellation of obesity,insulin resistance,high serum triglycerides,low high-density lipoprotein cholesterol,and high blood pressure.It increasingly affects more and more people and progressively evolves into a serious issue with widespread healthcare,cost,and quality of life associated consequences.MS is associated with increased morbidity and mortality due to cardiovascular or chronic liver disease.Conservative treatment,which includes diet,exercise,and antidiabetic agents,is the mainstay of treatment,but depends on patient compliance to medical treatment and adherence to lifestyle modification recommendations.Bariatric surgery has recently emerged as an appropriate alternative treatment with promising longterm results.Sleeve gastrectomy and Roux-en-Y gastric bypass constitute the most commonly performed procedures and have been proven both cost-effective and safe with low complication rates.Liver transplantation is the only definitive treatment for end-stage liver disease and its utilization in patients with nonalcoholic steatohepatitis has increased more than fivefold over the past 15 years.In this review,we summarize current state of evidence on the surgical treatment of MS.

Increasing Deaths Due to Malignancy in HIV＋ Patients is Associated with Integrase Inhibitor Therapy

Despite reductions in AIDS-related deaths, registries show HIV＋ patients are still dying at a younger age than HIV-peers. Although overall mortality has declined in this population, a growing percent of deaths are due to malignancy. Since the data demonstrating the growing percentage of deaths due to malignancy in the HIV＋ population is derived from registries, the study explores whether the subset dying from malignancy has particular characteristics that can be seen in a well-characterized cohort. In the well-characterized HIV＋ cohort, the percentage of deaths due to cancer was seen to increase over four years （2010-2013） from 21% to 24% to 38% to 40%. The mean CD4-count of those who died from malignancy was 252＋/-42 and 333＋/-36 in patients with death from other causes. The viral load was not suppressed in 26% of patients dying from malignancy. Of patients on integrase inhibitor therapy, 48% of deaths were due to malignancy while in patients not on this therapy, 10% of deaths were due to malignancy （relative risk = 4.8）. In HIV＋ patients, a low CD4-count, failure to achieve viral suppression, and use of integrase inhibitors were associated with malignancy as the cause of death. The association of a specific therapy, integrase inhibition, with malignancy is seen in the study.

Imaging in the COVID-19 era:Lessons learned during a pandemic

The first year of the coronavirus disease 2019(COVID-19)pandemic has been a year of unprecedented changes,scientific breakthroughs,and controversies.The radiology community has not been spared from the challenges imposed on global healthcare systems.Radiology has played a crucial part in tackling this pandemic,either by demonstrating the manifestations of the virus and guiding patient management,or by safely handling the patients and mitigating transmission within the hospital.Major modifications involving all aspects of daily radiology practice have occurred as a result of the pandemic,including workflow alterations,volume reductions,and strict infection control strategies.Despite the ongoing challenges,considerable knowledge has been gained that will guide future innovations.The aim of this review is to provide the latest evidence on the role of imaging in the diagnosis of the multifaceted manifestations of COVID-19,and to discuss the implications of the pandemic on radiology departments globally,including infection control strategies and delays in cancer screening.Lastly,the promising contribution of artificial intelligence in the COVID-19 pandemic is explored.

Continuous Lumbar Plexus Catheter Removal in Postoperative Total Hip Replacement Patients Receiving Warfarin Thromboprophylaxis: A Retrospective Analysis

Background and Objectives: Based on the case reports of hemorrhagic complications, recommendations for the removal of lumbar plexus catheters in anticoagulated patients were created. These guidelines are controversial as they limit the use of lumbar plexus blocks in postoperative anticoagulated patients. This study was designed to evaluate the incidence of hemorrhagic complications and coagulation status using International Normalized Ratio (INR) at the time of lumbar plexus catheter removal in patients receiving warfarin after total hip replacement. Methods: A retrospective study of 371 patients on warfarin thromboprophylaxis who received continuous lumbar plexus catheters for postoperative analgesia after total hip surgery was performed. The primary outcome measure was the incidence of bleeding complications after catheter removal;secondary outcome measures included warfarin dose, bridge therapy, incidence of deep vein thrombosis, pulmonary embolism (DVT/PE) and INR values upon catheter removal. Results: Almost all lumbar plexus catheters (93%;344/371) were removed at 72 hours. At the time of catheter removal, mean INR was 1.99 [1.42-2.41] (p = 0.015);67% of patients had an INR > 1.5 and half of these patients had INRs between 2.0-3.0;5% had INR’s between 3.0-4.0. There were no adverse bleeding complications or nerve injury after the removal of catheters. Conclusions: We observed no incidence of bleeding after lumbar plexus catheter removal despite 67 % of patients demonstrating INR’s > 1.5. Our retrospective analysis illustrates the relative safety of catheter removal in anticoagulated patients and suggests that the removal of lumbar plexus catheters can be safely performed with an INR > 1.5 in patients receiving warfarin.

Characterization of inflammation and insulin resistance in high-fat diet-induced male C57BL/6J mouse model of obesity

Background: Animal models of diet-induced obesity(DIO) are commonly used in medical research for mimicking human diseases. There is no universal animal model, and careful evaluation of variety of factors needs to be considered when designing new experiments. Here, we investigated the effect of 9 weeks high-fat diet(HFD) intervention, providing 60% energy from fat, on parameters of inflammation and insulin resistance in male C57 BL/6 J mice.Methods: Six weeks old mice were initiated on regular diet(RD) or HFD providing 60 kcal energy from fat for 9 weeks. Fasting blood glucose levels were measured by glucometer, and fasting plasma levels of insulin and proinflammatory cytokines by Luminex assay. Insulin sensitivity was evaluated by using QUICKI and HOMA2 indexes.Results: HFD mice showed ~ 40% higher body weight and ~ 20% larger abdominal circumference, due to an increase in the white adipose tissue mass. Liver examination revealed increased size and higher hepatic lipid accumulation in livers from HFD mice compared to their RD counterparts. Animals from the HFD group were characterized with significantly higher presence of crown-like structures(CLS) in WAT and higher plasma levels of proinflammatory cytokines(TNF-α, IL-6, leptin, MCP-1, PAI-1, and resistin). HFD-fed mice also demonstrated impaired insulin sensitivity(lower QUICKI, higher HOMA-insulin resistance(HOMA-IR), and lower HOMA-percent sensitivity(HOMA-%S)) index values.Conclusion: Male C57 BL/6 J mice on 9 weeks HFD providing 60 kcal energy from fat display impaired insulin sensitivity and chronic inflammation, thus making this DIO mouse model appropriate for studies of early stages of obesity-related pathology.

Altered leukocyte gene expression after traumatic spinal cord injury:clinical implications

In addition to changes in motor and sensory function, individuals with spinal cord injury （SCI） experience immunological changes. These changes are clinically significant, as infections are the leading cause of death for this population. Along with increased infections, inflammation is commonly observed in persons with SCI, where it may promote many common medical consequences. These include elevated risk of cardio- vascular disease, impaired wound healing, diabetes and neuropathic pain. It has also been proposed that chronic inflammation dampens neurological recovery. In order to identify therapeutic strategies to im- prove immune function, we need a greater understanding of the molecular changes that occur in immune cells after SCI. The purpose of this mini-review is to discuss two recent studies that used functional genom- ics to investigate gene expression in circulating leukocytes isolated from persons with SCI. In the future, the molecular pathways that are altered after SCI may be targeted to improve immunological function, as well as overall health and functional recovery, after SCI.

HMGB1 is a critical molecule in the pathogenesis of Gram-negative sepsis

Gram-negative sepsis is a severe clinical syndrome associated with significant morbidity and mortality.Lipopolysaccharide(LPS),expressed on Gram-negative bacteria,is a potent pro-inflammatory toxin that induces inflammation and coagulation via two separate receptor systems.One is Toll-like receptor 4(TLR4),expressed on cell surfaces and in endosomes,and the other is the cytosolic receptor caspase-11(caspases-4 and-5 in hu-mans).Extracellular LPS binds to high mobility group box 1(HMGB1)protein,a cytokine-like molecule.The HMGB1-LPS complex is transported via receptor for advanced glycated end products(RAGE)-endocytosis to the endolysosomal system to reach the cytosolic LPS receptor caspase-11 to induce HMGB1 release,inflammation,and coagulation that may cause multi-organ failure.The insight that LPS needs HMGB1 assistance to generate severe inflammation has led to successful therapeutic results in preclinical Gram-negative sepsis studies target-ing HMGB1.However,to date,no clinical studies have been performed based on this strategy.HMGB1 is also actively released by peripheral sensory nerves and this mechanism is fundamental for the initiation and prop-agation of inflammation during tissue injury.Homeostasis is achieved when other neurons actively restrict the inflammatory response via monitoring by the central nervous system and the vagus nerve through the cholinergic anti-inflammatory pathway.The neuronal control in Gram-negative sepsis needs further studies since a deeper understanding of the interplay between HMGB1 and acetylcholine may have beneficial therapeutic implications.Herein,we review the synergistic overlapping mechanisms of LPS and HMGB1 and discuss future treatment opportunities in Gram-negative sepsis.

Is the erythropoietin receptor the key to the identification of the central macrophage in erythroblastic islands?

Erythroblastic islands(EBI)are niches for mammalian erythropoiesis.1 They were first identified in 1958 by Marcel Bessis and consist of a group of differentiating erythroblasts surrounding a central macrophage.2 Over the years,a lot of attention has been paid to understand the role of the central macrophage in regulating the differentiation of the maturing erythroblasts within these islands and in defining the surface proteins thatmediate the interaction between the erythroblasts and the centralmacrophage.3–14While some progress has beenmade in these areas of investigation,the definitive identity of this central macrophage and its function is yet to be fully characterized.

Extracellular CIRP dysregulates macrophage bacterial phagocytosis in sepsis

In sepsis, macrophage bacterial phagocytosis is impaired, but the mechanism is not well elucidated. Extracellular cold-inducible RNA-binding protein (eCIRP) is a damage-associated molecular pattern that causes inflammation. However, whether eCIRP regulates macrophage bacterial phagocytosis is unknown. Here, we reported that the bacterial loads in the blood and peritoneal fluid were decreased in CIRP^(−/−) mice and anti-eCIRP Ab-treated mice after sepsis. Increased eCIRP levels were correlated with decreased bacterial clearance in septic mice. CIRP−/− mice showed a marked increase in survival after sepsis. Recombinant murine CIRP (rmCIRP) significantly decreased the phagocytosis of bacteria by macrophages in vivo and in vitro. rmCIRP decreased the protein expression of actin-binding proteins, ARP2, and p-cofilin in macrophages. rmCIRP significantly downregulated the protein expression of βPIX, a Rac1 activator. We further demonstrated that STAT3 and βPIX formed a complex following rmCIRP treatment, preventing βPIX from activating Rac1. We also found that eCIRP-induced STAT3 phosphorylation was required for eCIRP’s action in actin remodeling. Inhibition of STAT3 phosphorylation prevented the formation of the STAT3-βPIX complex, restoring ARP2 and p-cofilin expression and membrane protrusion in rmCIRP-treated macrophages. The STAT3 inhibitor stattic rescued the macrophage phagocytic dysfunction induced by rmCIRP. Thus, we identified a novel mechanism of macrophage phagocytic dysfunction caused by eCIRP, which provides a new therapeutic target to ameliorate sepsis.

Brain network markers of abnormal cerebral glucose metabolism and blood flow in Parkinson's disease

Neuroimaging of cerebral glucose metabolism and blood flow is ideally suited to assay widely-distributed brain circuits as a result of local molecular events and behavioral modulation in the central nervous system. With the progress in novel analytical methodology, this endeavor has succeeded in unraveling the mechanisms underlying a wide spectrum of neurodegenerative diseases. In particular, statistical brain mapping studies have made significant strides in describing the pathophysiology of Parkinson＇s disease （PD） and related disorders by providing signature biomarkers to determine the systemic abnormalities in brain function and evaluate disease progression, therapeutic responses, and clinical correlates in patients. In this article, we review the relevant clinical applications in patients in relation to healthy volunteers with a focus on the generation of unique spatial covariance patterns associated with the motor and cognitive symptoms underlying PD. These characteristic biomarkers can be potentially used not only to improve patient recruitment but also to predict outcomes in clinical trials.

Cold-inducible RNA-binding protein activates splenic T cells during sepsis in a TLR4-dependent manner

Cold-inducible RNA-binding protein (CIRP) is a novel inflammatory mediator that stimulates the release of proinflammatory cytokines from macrophages in sepsis. Given the immune dysregulation that characterizes sepsis, the effect of CIRP on other immune cells is an area of increasing interest that has not yet been studied. In the present study, we hypothesized that extracellular CIRP promotes activation of T lymphocytes in the spleen during sepsis. We observed that mice subjected to sepsis by cecal ligation and puncture showed significantly higher expression of the early activation markers CD69 and CD25 at 20 h on CD4+ splenic T cells, and significantly higher CD69 expression on CD8+ splenic T cells compared with sham-operated controls. Furthermore, at 20 h after receiving intravenous injection of recombinant murine CIRP (rmCIRP, 5 mg/kg body weight (BW)) or PBS (vehicle), those mice receiving rmCIRP showed significantly increased expression of CD69 and CD25 on both CD4+ and CD8+ splenic T cells. This effect, however, was not seen in TLR4-deficient mice after rmCIRP injection. In addition, treatment with CIRP predisposed CD4+ T cells to a Th1 hyperinflammatory response profile, and influenced CD8+ T cells toward a cytotoxic profile. Taken together, our findings indicate that CIRP is a proinflammatory mediator that plays an important role in T-cell dysregulation during sepsis in a TLR4-dependent manner.

EGFR signaling augments TLR4 cell surface expression and function in macrophages via regulation of Rab5a activation

Dear Editor,oll-like receptor 4(TLR4)is a key receptor sensing bacterial lipopolysaccharide(LPS),and is the most investigated member of the Tol-like receptor family(Kawai and Akira,2007;Kayagaki et al,2013;Klein et al.,2015).Cell surface TLR4 expression is determined by the balance between receptor trafficking from the Golgi apparatus to the cell membrane,and internalization of the cell surface receptor into endosomal compartments(Saltoh,2009).In bone mar-row-derived macrophages(BMDM),we observed LPS-in-duced EGFR phosphorylation on the surface of BMDM,and this was inhibited by pretreatment with PD168393 or TAPI-1(Fig.S1).Next,we measured dynamic changes in cell sur-face TLR4 expression after LPS treatment.At6,12,and 24 h after LPS treatment,TLR4 expression on the surface of BMDM was increased^2-,~6-,and^9-fold,respectively,as compared with controls.

Correction to:EGFR signaling augments TLR4 cell surface expression and function in macrophages via regulation of Rab5a activation

Figure 1.EGFR activation promotes TLR4 phosphorylation and cell surface expression of TLR4 in response to LPS.(A and B)BMDM were treated with LPS(1μg/mL)for 6,12,or 24 h in the presence or absence of pretreatment of PD or TAPI-1.(A)Flow cytometry analysis of cell surface TLR4 intensity in BMDM.(B)Flow cytometry analysis of cell surface TLR4 intensity in BMDM.(C and D)WT(C57BL76)mice were treated with LPS(10 mg/kg,i.p.).In some groups,mice were pretreated with erlotinib(100 mg/kg,gavage administration)at 30 min prior to LPS i.p.