Sterile Inflammatory Response Research Articles

Effect of Microbubble Size, Composition, and Multiple Sonication Points on Sterile Inflammatory Response in Focused Ultrasound-Mediated Blood-Brain Barrier Opening.

Blood-brain barrier opening (BBBO) using focused ultrasound (FUS) and microbubbles (MBs) has emerged as a promising technique for delivering therapeutics to the brain. However, the influence of various FUS and MB parameters on BBBO and subsequent sterile inflammatory response (SIR) remains unclear. In this study, we investigated the effects of MB size and composition, as well as the number of FUS sonication points, on BBBO and SIR in an immunocompetent mouse model. Using MRI-guided MB + FUS, we targeted the striatum and assessed extravasation of an MRI contrast agent to assess BBBO and RNaseq to assess SIR. Our results revealed distinct effects of these parameters on BBBO and SIR. Specifically, at a matched microbubble volume dose (MVD), MB size did not affect the extent of BBBO, but smaller (1 μm diameter) MBs exhibited a lower classification of SIR than larger (3 or 5 μm diameter) MBs. Lipid-shelled microbubbles exhibited greater BBBO and a more pronounced SIR compared to albumin-shelled microbubbles, likely owing to the latter's poor in vivo stability. As expected, increasing the number of sonication points resulted in greater BBBO and SIR. Furthermore, correlation analysis revealed strong associations between passive cavitation detection measurements of harmonic and inertial MB echoes, BBBO, and the expression of SIR gene sets. Our findings highlight the critical role of MB and FUS parameters in modulating BBBO and subsequent SIR in the brain. These insights inform the development of targeted drug delivery strategies and the mitigation of adverse inflammatory reactions in neurological disorders.

Postoperative ileus-Immune mechanisms and potential therapeutic interventions.

Postoperative ileus (POI) is a condition marked by a temporary suppression of gastrointestinal motility following abdominal surgery. The mechanism of POI encompasses various factors and is characterized by two phases: the early neurogenic phase involving both adrenergic and non-adrenergic neural pathways; the later immune-mediated phase is characterized by a sterile inflammatory response that lasts several days. Activation of muscularis macrophages triggers a sterile inflammatory process that results in dysfunction of the enteric nervous system (ENS) and a reversible inhibition of gastrointestinal motility. In this minireview, recent insights in the pathophysiological mechanisms underlying POI and potential new therapeutic strategies are described.

Pulsed focused ultrasound alters the proteomic profile of the tumor microenvironment in a syngeneic mouse model of glioblastoma.

Glioblastoma (GBM), a lethal primary adult malignancy, is difficult to treat because of the restrictive nature of the blood-brain barrier (BBB), blood-tumor barrier (BTB), and the immunosuppressive tumor microenvironment (TME). Since pulsed focused ultrasound (pFUS) is currently used to improve therapeutic deliveries across these barriers, this study aims to characterize the impact of pFUS on the TME proteomics upon opening the BBB and BTB. We utilized MRI-guided, pFUS with ultrasound contrast microbubbles (termed 'pFUS' herein) to selectively and transiently open the BBB and BTB investigating proteomic modifications in the TME. Utilizing an orthotopically-allografted mouse GL26 GBM model (Ccr2RFP/wt - Cx3cr1GFP/wt), pFUS's effect on glioma proteomics was evaluated using a Luminex 48-plex assay. pFUS treated tumors exhibited increases in pro-inflammatory cytokines, chemokines, and trophic factors (CCTFs). Proteomic changes in tumors tend to peak at 24 h after single pFUS session (1x), with levels then plateauing or declining over the subsequent 24 h. Tumors receiving three pFUS sessions (3x) showed elevated CCTFs levels peaking as early as 6 h after the third session. pFUS together with microbubbles induces a sterile inflammatory response in the TME of a mouse GBM tumor. Moreover, this proinflammatory shift can be sustained and perhaps primed for more rapid responses upon multiple sessions of pFUS. These findings raise the intriguing potential that pFUS-induced BBB and BTB opening may not only be effective in facilitating the therapeutic agent delivery, but also be harnessed to modify the TME to assist immunotherapies in overcoming immune evasion in GBM.

Abstract We055: Role of Classical Dendritic Cells in the Sterile Inflammatory Response Following Myocardial Infarction

Myocardial infarction and the subsequent development of chronic ischemic cardiomyopathy is the most common cause of congestive heart failure. Infarction is associated with an intense sterile inflammatory response which can lead to adverse remodeling over the long term. Dendritic cells (DCs) are antigen presenting cells that function as a bridge between innate and adaptive immunity. Precursor DCs give rise to several distinct classical DC (cDC) subsets that mediate a variety of functions. The cDC1 subset is essential for cross-presentation of antigens to CD8 + T cells, while the cDC2 lineage is a potent inducer of CD4 + T cell proliferation. The aim of the study was to characterize the profile of the cDC populations present during the various stages of the development of chronic ischemic cardiomyopathy. We hypothesized that cDCs are essential mediators of chronic LV remodeling in the period following ischemic myocardial injury. We sought to determine which specific cDC subtype (cDC1 vs cDC2) forms the predominant population in the heart and secondary lymphoid tissues following ischemic injury. Adult male C57BL/6 (WT) mice underwent non-perfused myocardial infarction by ligating the left anterior descending artery (LAD) to induce sterile injury, with sham operated mice used as controls. Left ventricular (LV) remodeling was assessed by echocardiography at 1 w and 8 w following surgery. Alterations in cDC1 (CD45+CD11c+CD103-XCR1-) and cDC2 (CD45+CD11c+CD103+XCR1+) profile were examined by flow cytometry. When compared with the sham operated mice, mice with ischemic cardiomyopathy following LAD ligation exhibited the following features. There is an initial influx of cDC2 into the myocardium 1 w after MI (mean of 3.0% vs 0.26% of CD45 + leukocytes, p=0.02). This is followed by a subsequent influx of cDC1 into the myocardium 4 weeks after MI (mean of 1.98% vs 0.16% of CD45 + leukocytes, p=0.001). This influx of cDC into the heart is accompanied by an egress of cDC from the spleen (mean of 0.37% vs 0.76% of CD45 + leukocytes, P=0.001) at 4 weeks following MI. In conclusion, the findings of our study suggest that there is an initial influx of cDC2 followed by a more sustained influx of cDC1 into the myocardium in the weeks following an infarct. Antigen presentation by cDC likely plays a critical role in driving the inflammatory response and inducing chronic LV remodeling in the period following MI.

Comprehensive assessment of blood–brain barrier opening and sterile inflammatory response: unraveling the therapeutic window

Microbubbles (MBs) combined with focused ultrasound (FUS) has emerged as a promising noninvasive technique to permeabilize the blood–brain barrier (BBB) for drug delivery into the brain. However, the safety and biological consequences of BBB opening (BBBO) remain incompletely understood. This study aims to investigate the effects of two parameters mediating BBBO: microbubble volume dose (MVD) and mechanical index (MI). High-resolution MRI-guided FUS was employed in mouse brains to assess BBBO by manipulating these two parameters. Afterward, the sterile inflammatory response (SIR) was studied 6 h post-FUS treatment. Results demonstrated that both MVD and MI significantly influenced the extent of BBBO, with higher MVD and MI leading to increased permeability. Moreover, RNA sequencing revealed upregulation of major inflammatory pathways and immune cell infiltration after BBBO, indicating the presence and extent of SIR. Gene set enrichment analysis identified 12 gene sets associated with inflammatory responses that were significantly upregulated at higher MVD or MI. A therapeutic window was established between therapeutically relevant BBBO and the onset of SIR, providing operating regimes to avoid damage from stimulation of the NFκB pathway via TNFɑ signaling to apoptosis. These results contribute to the optimization and standardization of BBB opening parameters for safe and effective drug delivery to the brain and further elucidate the underlying molecular mechanisms driving sterile inflammation.

Review on Long Non-Coding RNAs as Biomarkers and Potentially Therapeutic Targets for Bacterial Infections.

The confrontation between humans and bacteria is ongoing, with strategies for combating bacterial infections continually evolving. With the advancement of RNA sequencing technology, non-coding RNAs (ncRNAs) associated with bacterial infections have garnered significant attention. Recently, long ncRNAs (lncRNAs) have been identified as regulators of sterile inflammatory responses and cellular defense against live bacterial pathogens. They are involved in regulating host antimicrobial immunity in both the nucleus and cytoplasm. Increasing evidence indicates that lncRNAs are critical for the intricate interactions between host and pathogen during bacterial infections. This paper emphatically elaborates on the potential applications of lncRNAs in clinical hallmarks, cellular damage, immunity, virulence, and drug resistance in bacterial infections in greater detail. Additionally, we discuss the challenges and limitations of studying lncRNAs in the context of bacterial infections and highlight clear directions for this promising field.

Mitochondrial Quality Control Processes at the Crossroads of Cell Death and Survival: Mechanisms and Signaling Pathways.

Biological aging results from an accumulation of damage in the face of reduced resilience. One major driver of aging is cell senescence, a state in which cells remain viable but lose their proliferative capacity, undergo metabolic alterations, and become resistant to apoptosis. This is accompanied by complex cellular changes that enable the development of a senescence-associated secretory phenotype (SASP). Mitochondria, organelles involved in energy provision and activities essential for regulating cell survival and death, are negatively impacted by aging. The age-associated decline in mitochondrial function is also accompanied by the development of chronic low-grade sterile inflammation. The latter shares some features and mediators with the SASP. Indeed, the unloading of damage-associated molecular patterns (DAMPs) at the extracellular level can trigger sterile inflammatory responses and mitochondria can contribute to the generation of DAMPs with pro-inflammatory properties. The extrusion of mitochondrial DNA (mtDNA) via mitochondrial outer membrane permeabilization under an apoptotic stress triggers senescence programs. Additional pathways can contribute to sterile inflammation. For instance, pyroptosis is a caspase-dependent inducer of systemic inflammation, which is also elicited by mtDNA release and contributes to aging. Herein, we overview the molecular mechanisms that may link mitochondrial dyshomeostasis, pyroptosis, sterile inflammation, and senescence and discuss how these contribute to aging and could be exploited as molecular targets for alleviating the cell damage burden and achieving healthy longevity.

Molecular evidence of sterile tissue damage during pathogenesis of the pododermatitis aseptica hemorrhagica circumscripta is associated with disturbed epidermal-dermal homeostasis

Podermatitis aseptica hemorrhagica circumscripta is associated with metalloproteinase 2 weakening of distal phalangeal suspensory structures and sinkage of the distal phalanx in the claw capsule. Pressure from the tuberculum flexorium on the sole epidermis and dermis produces hemorrhagic tissue injury and defective horn production appearing as yellow-red, softened claw horn in region 4 of the sole. A model of the MAPK/ERK signal cascade orchestrating epidermal-dermal homeostasis was employed to determine if sterile inflammatory responses are linked to disturbed signal transduction for epidermal homeostasis in sole epidermis and dermis. The objective was to assess shifts in target genes of inflammation, up- and downstream MAPK/ERK signal elements, and targeted genes supporting epidermal proliferation and differentiation. Sole epidermis and dermis was removed from lateral claws bearing lesions of podermatitis aseptica hemorrhagica circumscripta, medial claws from the same limb and lateral claws from completely normal limbs of multiparous, lactating Holstein cows. The abundance levels of targeted transcripts were evaluated by real-time QPCR. Lesion effects were assessed by ANOVA, and mean comparisons were performed with t-tests to assess variations between mean expression in ulcer-bearing or medial claw dermis and epidermis and completely normal lateral claw dermis and epidermis or between ulcer-bearing dermis and epidermis and medial claw dermis and epidermis. The lesions were sterile and showed losses across multiple growth factors, their receptors, several downstream AP1 transcription components, CMYC, multiple cell cycle and terminal differentiation elements conducted by MAPK/ERK signals and β 4, α 6 and collagen 17A hemidesmosome components. These losses coincided with increased cytokeratin 6, β 1 integrin, proinflammatory metalloproteinases 2 and 9, IL1B and physiologic inhibitors of IL1B, the decoy receptor and receptor antagonist. Medial claw epidermis and dermis from limbs with lateral claws bearing podermatitis aseptica hemorrhagica circumscripta showed reductions in upstream MAPK/ERK signal elements and downstream targets that paralleled those in hemorrhagic lesions. Inhibitors of IL1B increased in the absence of real increases in inflammatory targets in the medial claw dermis and epidermis. Losses across multiple signal path elements and downstream targets were associated with negative effects on targeted transcripts supporting claw horn production and wound repair across lesion-bearing lateral claws and lesion-free medial claw dermis and epidermis. It was unclear if the sterile inflammation was causative or a consequence of these perturbations.

β-Caryophyllene promotes the survival of random skin flaps by upregulating the PI3K/AKT signaling pathway

BackgroundFlap transplantation is a widely used plastic repair technique in surgical procedures, aimed at addressing skin defects resulting from diverse wounds and diseases. However, due to the insufficient blood supply after flap surgery, the occurrence of ischemia-reperfusion injury, and an excessive sterile inflammatory response, flaps frequently develop complications (e.g., partial or complete ischemic necrosis). These complications have adverse effects on wound healing and repair. β-Caryophyllene (BCP) is a bicyclic sesquiterpene that is widely present in plants. It mitigates oxidative stress and inflammatory responses, demonstrates neuroprotective and analgesic properties, and serves a protective function in organs or tissues subjected to ischemia-reperfusion injury. However, no study has confirmed whether BCP can be used in the field of flap transplantation to improve the flap survival rate. MethodsTo assess the impact of BCP on random flap survival, we constructed a modified McFarlane random flap model on the rat. After 7 consecutive days of gavage with different doses of BCP, we measured the survival area ratio, angiogenesis, blood perfusion, tissue inflammation level, apoptosis-related protein levels, and the PI3K/AKT signaling pathway expression of the random flap. ResultsBCP treatment increased the survival area of the flap in a dose-dependent manner after random flap transplantation in rats. BCP mainly promoted the formation of tissue blood vessels, improved flap blood perfusion, limited the local inflammatory response, and reduced apoptosis. In addition, we demonstrated that BCP works primarily by promoting the PI3K/AKT signaling expression while enhancing the phosphorylation of AKT. Administration of wortmannin, a selective inhibitor of PI3K, eliminated the effects of BCP. ConclusionBCP can promote the survival of random flaps by upregulating the PI3K/AKT signaling pathway, increasing tissue blood perfusion, and limiting the inflammatory response and apoptosis.

ProBDNF-p75NTR signaling in sterile inflammation

Trauma, injury, and surgical procedures cause tissue damage, sterile inflammatory responses, and significant immune system stress leading to immune dysregulation and increased susceptibility to secondary infections. The spleen is a reservoir of myeloid immune cells that are involved in inflammation following various tissue injuries. One potential signaling pathway that may be involved in this process is proBDNF-p75NTR signaling in myeloid cells. Brain derived neurotrophic factor (BDNF) is a previously reported myokine, however there is little known about its role in skeletal muscle injury. We recently found that p75NTR, the receptor for proBDNF, was significantly upregulated (p=0.004) in myeloid cells isolated from the spleen of animals with hindlimb IR injury compared to sham controls, potentially in a sexually dimorphic manner. Our previous studies have shown that proBDNF, the precursor protein to BDNF, is the predominant form of BDNF expressed in skeletal muscle tissue and is significantly upregulated following tourniquet induced hind limb IR injury in mice (p=0.013). We hypothesize that proBDNF released from injured skeletal muscle could act through p75NTR in myeloid cells to regulate inflammatory responses following IR injury. The hind limb IR injury was induced using a tourniquet model in which an orthodontic rubber band placed on the hind limb at the level of the hip and left in place for 1.5 hours followed by tourniquet removal and reperfusion. A series of in vitro experiments were conducted on myeloid cells isolated from the spleen of sham mice, or mice with skeletal muscle IR injury. As a model of secondary infection, myeloid cells were stimulated with lipopolysaccharide (LPS) and cytokine release into culture media was measured using ELISA assays. We found that in myeloid cells isolated from IR injured animals, LPS stimulated cytokine release was increased. Further, treating isolated myeloid cells from IR injured animals with recombinant cleavage resistant proBDNF increased cytokine release compared to controls. To confirm that p75NTR on myeloid cells was at least partially responsible for the induction of cytokine expression following LPS or proBDNF stimulation, myeloid cells were treated with LM11A-31, a modulator of p75NTR in combination with LPS or proBDNF. Treatment with C31 (100ng) blunted cytokine release following LPS and proBDNF stimulation. These results suggest that the p75NTR pathway is involved in the innate immune function of splenic myeloid cells in injury induced inflammation and therefore is potentially a novel therapeutic target. This work was funded by NIH grant R01HL147105, NIH Training Grant T32-GM136503, and NIH F31 Fellowship F31HL167480. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Endometrial stromal cells define the fate of decidual Dendritic Cells through endoplasmic reticulum stress transmission

Abstract Endometrial stromal cells acquire a secretory profile associated with a physiological endoplasmic reticulum stress (ERS) and the onset of a sterile inflammatory response to sustain embryo implantation. Here we evaluated the impact of endometrial stromal cells on Dendritic Cells (DC) differentiation through ERS-transmission. We used an in vitro model based on differentiated-monocytes from healthy women (with rhGM-CSF+rhIL-4) cultured in the absence/presence of Conditioned Media (CM) from stressed Human Endometrial Stromal Cells (HESC stimulated with Thapsigargin). Those DC cultures differentiated with stressed-HESC showed a lower frequency of CD1a+CD14- accompanied by an increased CD86high cell-population and higher COX2 expression. We also detected an increase in IL-1β secretion and in AnnexinV+/PI+ cell-population, indicating a lytic programmed cell death. The ERS-transmission was confirmed by increased IRE1α expression on DC. In fact, IRE1α inhibitor prevented the conditioning to a pro-inflammatory DC profile. Finally, to investigate the impact of the DC-inflammatory profile on blastocyst implantation ability, we tested trophoblastic spheroids migration. Blastocyst-like spheroids displayed an altered trophoblast migration when were cultured with supernatant from stressed-DC. These results suggest that ERS might be transmitted from stromal cells to DC and its fine balance is required to maintain tolerance for successful embryo implantation and trophoblast migration.

DAMP sensing and sterile inflammation: intracellular, intercellular and inter-organ pathways.

Damage-associated molecular patterns (DAMPs) are endogenous molecules that are released from host cells as a result of cell death or damage. The release of DAMPs in tissues is associated with loss of tissue homeostasis. Sensing of DAMPs by innate immune receptors triggers inflammation, which can be beneficial in initiating the processes that restore tissue homeostasis but can also drive inflammatory diseases. In recent years, the sensing of intracellular DAMPs has received extensive attention in the field of sterile inflammation. However, emerging studies have shown that DAMPs that originate from neighbouring cells, and even from distal tissues or organs, also mediate sterile inflammatory responses. This multi-level sensing of DAMPs is crucial for intercellular, trans-tissue and trans-organ communication. Here, we summarize how DAMP-sensing receptors detect DAMPs from intracellular, intercellular or distal tissue and organ sources to mediate sterile inflammation. We also discuss the possibility of targeting DAMPs or their corresponding receptors to treat inflammatory diseases.

Sterile Inflammatory Response and Surgery-Related Trauma in Elderly Patients with Subtrochanteric Fractures.

Sterile inflammation is a natural response of the organism in the absence of microorganisms, which is triggered in correspondence with the degree of tissue damage sustained after a surgical procedure. The objective of this study was to explore the values of postoperative hematological-derived biomarkers in assessing the sterile inflammatory response magnitude related to the invasiveness of the surgical reduction technique used for subtrochanteric fractures (STFs) treatment. A retrospective, observational cohort research was conducted between January 2021 and October 2023 that included a total of 143 patients diagnosed with acute subtrochanteric fractures who underwent long Gamma Nail (LGN) fixation. According to the surgical reduction technique used, they were divided into two groups: group 1, which consisted of those with a closed reduction and internal fixation (CRIF); and group 2, which consisted of those with an open reduction internal fixation (ORIF). Between groups, statistically significant differences (p < 0.05) were found in relation to days to surgery, length of hospital stay (LOHS), duration of surgery, postoperative hemoglobin (HGB) levels, neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), monocyte-lymphocyte ratio (MLR), systemic inflammation index (SII), systemic inflammation response index (SIRI), and aggregate inflammation systemic index (AISI). The receiver operating characteristics (ROC) curve analysis revealed that all ratios presented a high diagnostic ability (p < 0.0001) with NLR > 6.95 being the most reliable (sensitivity 94.8% and specificity 70.6%). Moreover, the multivariate regression model confirmed that sterile immune response after orthopedic interventions can be assessed in an almost equal and non-dependent manner using these biomarkers. Postoperative NLR, PLR, MLR, SII, SIRI, and AISI ratios are closely correlated to the sterile inflammatory response magnitude, due to the extent of surgical dissection performed during internal fixation procedures of subtrochanteric femur fractures.

Targeting Cx43 to Reduce the Severity of Pressure Ulcer Progression.

In the skin, repeated incidents of ischemia followed by reperfusion can result in the breakdown of the skin and the formation of a pressure ulcer. Here we gently applied paired magnets to the backs of mice to cause ischemia for 1.5 h and then removed them to allow reperfusion. The sterile inflammatory response generated within 4 h causes a stage 1 pressure ulcer with an elevation of the gap junction protein Cx43 in the epidermis. If this process is repeated the insult will result in a more severe stage 2 pressure ulcer with a breakdown of the epidermis 2-3 days later. After a single pinch, the elevation of Cx43 in the epidermis is associated with the inflammatory response with an increased number of neutrophils, HMGB1 (marker of necrosis) and RIP3 (responsible for necroptosis). Delivering Cx43 specific antisense oligonucleotides sub-dermally after a single insult, was able to significantly reduce the elevation of epidermal Cx43 protein expression and reduce the number of neutrophils and prevent the elevation of HMGB1 and RIP3. In a double pinch model, the Cx43 antisense treatment was able to reduce the level of inflammation, necroptosis, and the extent of tissue damage and progression to an open wound. This approach may be useful in reducing the progression of stage 1 pressure ulcers to stage 2.

Acute generalized exanthematous pustulosis: Analysis of cases managed in a Tunisian tertiary hospital

Acute generalized exanthematous pustulosis (AGEP) is a severe and life-threatening cutaneous adverse reaction. Drug-induced AGEP is mainly related to antibiotics. More recently, AGEP following spider bites has been increasingly described. Treatment includes withdrawal of the offending drug and supportive care. In Tunisia, data concerning severe cutaneous adverse reactions (SCARs) in general and especially AGEP is lacking. Herein, we conducted a retrospective study to investigate the epidemiological, clinical characteristics and etiologies of AGEP referred to the Dermatology department. Our study included 32 cases of AGEP. AGEP cases occurred in overall 8.9% of all SCARs referred to the department during the same period study. The majority were females (24 women and 7 men). The median age of the patients was 33 years. A history of psoriasis was reported in 16.1% of patients. All patients presented with an extensive erythematous rash with pinhead pustules. Neutrophil hyperleukocytosis (greater than 7000/mm3) was noted in 17 patients (63% of cases). It was associated with hypereosinophilia exceeding 500 elements/mm3 in 8 cases (29.6%). Drug-induced AGEP was reported in 53% of cases. Antibiotics were implicated in the majority of cases. Delay in onset ranged from 15hours to 7 days, with an average of 2.8 days. A non-drug-induced etiology was considered if the pharmacological investigation was negative, or if a clear non-drug trigger was found. It was retained in ten cases (48.4% of all observations). Spider bites were revealed in 8 cases. AGEP represents a severe, usually drug-related skin reaction. It is classified as a type IVd reaction mediating T cell-related sterile neutrophilic inflammatory response. It typically occurs within 24-48h of ingestion of the offending drug. Antibiotics are the most common drug family to cause AGEP. Spider bites were involved in 25.8% of cases in our study, as important as antibiotic-induced AGEP. Analysis of the particularities of AGEP according to etiology, whether drug-induced or not, revealed the presence of an initial escarotic lesion (P=0.01) and the finding of blood hypereosinophilia (P=0.014) in the non-drug AGEP group were the distinguishing features. Blood hyperesoniophilia, more frequent in the non-drug AGEP group, suggests a pathophysiology probably different from that of the drug AGEP group. Clinicians should be aware of both etiologies. Our study focuses on the importance of AGEP associated with spider bite as a potential triggering factor in Tunisia.

The roles of liver sinusoidal endothelial cells in liver ischemia/reperfusion injury.

Liver ischemia/reperfusion injury (IRI) is a major complication after partial hepatectomy and liver transplantation and during hypovolemic shock and hypoxia-related diseases. Liver IRI is a current research hotspot. The early stage of liver IRI is characterized by injury and dysfunction of liver sinusoidal endothelial cells (LSECs), which, along with hepatocytes, are the major cells involved in liver injury. In this review, we elaborate on the roles played by LSECs in liver IRI, including the pathological features of LSECs, LSECs exacerbation of the sterile inflammatory response, LSECs interactions with platelets and the promotion of liver regeneration, and the activation of LSECs autophagy. In addition, we discuss the study of LSECs as therapeutic targets for the treatment of liver IRI and the existing problems when applying LSECs in liver IRI research.

Knockout of the C3a receptor protects against renal ischemia reperfusion injury by reduction of NETs formation.

Renal ischemia/reperfusion (I/R) injury is a local sterile inflammatory response driven by innate immunity. Emerging data have revealed that complement and neutrophils contribute to hyperinflammation and oxidative stress in I/R induced acute kidney injury (AKI). However, the interplay between the C3a/C3aR axis and neutrophil extracellular traps (NETs) is imcompletelyunderstood. Here, we utilize genetically engineered mouse models and pharmacological inhibitors to investigate this association. The C3a/C3aR axis is found to promote neutrophil recruitment and NETs formation, thereby accelerating renal damage and dysfunction. Knockout of C3aR restores NETs release and improves renal function after I/R injury. Antibody-mediated blockade of NETs can also significantly ameliorate renal tubular injury and inflammation. Consistently, under stimulation by C3a, neutrophils are activated to promoteNETs formation and subsequent renal tubular epithelial cell damage,andblocking C3aRrescued the injury.Interfering with reactive oxygen species (ROS) accumulation in neutrophils by antioxidant treatment significantly attenuates NETs formation. Our findings demonstrate that the C3a/C3aR-ROS-NETs axis constitutes a promising target for prevention or treatment of renal I/R injury.

Liver ischemia-reperfusion injury: From trigger loading to shot firing.

An ischemia-reperfusion injury (IRI) results from a prolonged ischemic insult followed by the restoration of blood perfusion, being a common cause of morbidity and mortality, especially in liver transplantation. At the maximum of the potential damage, IRI is characterized by 2 main phases. The first is the ischemic phase, where the hypoxia and vascular stasis induces cell damage and the accumulation of damage-associated molecular patterns and cytokines. The second is the reperfusion phase, where the local sterile inflammatory response driven by innate immunity leads to a massive cell death and impaired liver functionality. The ischemic time becomes crucial in patients with underlying pathophysiological conditions. It is possible to compare this process to a shooting gun, where the loading trigger is the ischemia period and the firing shot is the reperfusion phase. In this optic, this article aims at reviewing the main ischemic events following the phases of the surgical timeline, considering the consequent reperfusion damage.

Sterile inflammation in liver transplantation.

Sterile inflammation is the immune response to damage-associated molecular patterns (DAMPs) released during cell death in the absence of foreign pathogens. In the setting of solid organ transplantation, ischemia-reperfusion injury results in mitochondria-mediated production of reactive oxygen and nitrogen species that are a major cause of uncontrolled cell death and release of various DAMPs from the graft tissue. When properly regulated, the immune response initiated by DAMP-sensing serves as means of damage control and is necessary for initiation of recovery pathways and re-establishment of homeostasis. In contrast, a dysregulated or overt sterile inflammatory response can inadvertently lead to further injury through recruitment of immune cells, innate immune cell activation, and sensitization of the adaptive immune system. In liver transplantation, sterile inflammation may manifest as early graft dysfunction, acute graft failure, or increased risk of immunosuppression-resistant rejection. Understanding the mechanisms of the development of sterile inflammation in the setting of liver transplantation is crucial for finding reliable biomarkers that predict graft function, and for development of therapeutic approaches to improve long-term transplant outcomes. Here, we discuss the recent advances that have been made to elucidate the early signs of sterile inflammation and extent of damage from it. We also discuss new therapeutics that may be effective in quelling the detrimental effects of sterile inflammation.

Mitigation of acetaminophen-induced liver toxicity by the novel phosphatidylinositol 3-kinase inhibitor alpelisib.

The sterile inflammatory response mediated by Toll-like receptors (TLRs) 4 and 9 is implicated in the massive hepatic damage caused by acetaminophen (APAP)-overdose. There is a crosstalk between TLR-dependent signaling with other intracellular kinases like phosphatidylinositol 3-kinases (PI3Ks). Nevertheless, the detailed role of PI3Kα is still unknown in hepatic sterile inflammation. Accordingly, the effect of the novel PI3Kα inhibitor alpelisib was investigated in the setting of APAP-driven sterile inflammation in the liver. This was examined by pretreating mice with alpelisib (5 and 10mg/kg, oral) 2h before APAP (500mg/kg, i.p.)-intoxication. The results indicated that alpelisib dose-dependently lowered APAP-induced escalation in serum liver function biomarkers and hepatic necroinflammation score. Alpelisib also attenuated APAP-induced rise in cleaved caspase 3 and proliferating cell nuclear antigen (PCNA) in the liver hepatocytes, as indices for apoptosis and proliferation. Mechanistically, inhibition of PI3Kα by alpelisib limited APAP-induced overproduction of the pro-inflammatory tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 in the blood circulation via switching off the activation of several signal transduction proteins, including extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), signal transducer and activator of transcription-3 (Stat-3), glycogen Synthase Kinase (GSK)-3β and nuclear factor (NF)-κB. Alpelisib also impaired APAP-instigated immune cell infiltration in the liver via reducing systemic granulocyte/macrophage-colony stimulating factor (GM-CSF) release and reversed APAP-induced abnormalities in the systemic and hepatic levels of the anti-inflammatory IL-10 and IL-22. In conclusion, selective modulation of the PI3Kα activity by alpelisib can hinder the inflammatory response and infiltration of immune cells occurring by APAP-hepatotoxicity.