Model Of Septic Shock Research Articles

Predicting septic shock upon arrival to the emergency department

Sepsis continues to kill children around the world. The death of a child with sepsis in New York State resulted in a state-wide mandate for sepsis care in 2013 (JAMA 2018;320:358-67). This mandate was later found to be associated with lower risk of mortality from pediatric sepsis. Since then, other states have promulgated similar mandates. Survival from sepsis depends on early diagnosis and timely intervention, preferably before septic shock occurs. Yet, clinicians often fail to recognize sepsis in time to prevent deterioration to septic shock. In this volume of The Journal, Scott et al derived and validated the first prediction model for pediatric septic shock. They used variables that are easily available from the electronic health records and are known upon arrival to the emergency department, including the initial vital signs. The model, which was developed using a modern predictive algorithm, strongly discriminated the risk of septic shock and added predictive value to initial clinician suspicion of sepsis. The model can be incorporated in the electronic health records to automate the stratification of the risk of pediatric shock. Stratification of the risk of pediatric shock will allow for timely intervention before deterioration occurs. It is a critical step toward the prevention of death from pediatric sepsis. The prediction model by Scott et al is a positive step toward this direction. Article page 145 ▸ Development and Validation of a Predictive Model of the Risk of Pediatric Septic Shock Using Data Known at the Time of Hospital ArrivalThe Journal of PediatricsVol. 217PreviewTo derive and validate a model of risk of septic shock among children with suspected sepsis, using data known in the electronic health record at hospital arrival. Full-Text PDF

ICH3, a selective alpha7 nicotinic acetylcholine receptor agonist, modulates adipocyte inflammation associated with obesity.

The alpha7 nicotinic acetylcholine receptor (α7nAChR), involved in the modulation of inflammation and insulin sensitivity, is downregulated in white adipose tissue (WAT) of obese patients. This study aims to test the ability of a selective synthetic α7nAChR agonist, the spirocyclic Δ2-isoxazoline derivative (R)-(-)-ICH3 (ICH3), to counteract acute inflammation and obesity-associated modifications in WAT. We employed the LPS-septic shock murine model, human primary adipocytes and diet-induced obese (DIO) mice. Inflammatory factor expression was assessed by ELISA and quantitative real-time PCR. Flow cytometry was employed to define WAT inflammatory infiltrate. Insulin signaling was monitored by quantification of AKT phosphorylation. In the septic shock model, ICH3 revealed antipyretic action and reduced the surge of circulating cytokines. In vitro, ICH3 stimulation (10µM) preserved viability of human adipocytes, decreased IL-6 mRNA (P < 0.05) and blunted LPS-induced peak of TNFα (P < 0.05) and IL-6 (P < 0.01). Chronic administration of ICH3 to DIO mice was associated with lower numbers of CD8+ T cells (P < 0.05) and to changed WAT expression of inflammatory factors (Hp, P < 0.05; CD301/MGL1, P < 0.01; Arg-1, P < 0.05). As compared to untreated, ICH3 DIO mice exhibited improved insulin signaling in the skeletal muscle (P < 0.01) mirrored by an improved response to glucose load (ipGTT: P < 0.05 at 120min). We proved that ICH3 is an anti-inflammatory drug, able to reduce inflammatory cytokines in human adipocytes and to blunt the effects of obesity on WAT inflammatory profile, on glucose tolerance and on tissue insulin sensitivity.

Ginsenoside metabolite 20(S)-protopanaxatriol from Panax ginseng attenuates inflammation-mediated NLRP3 inflammasome activation.

Panax ginseng C.A. Meyer (Araliaceae), has been used in traditional medicine for preventive and therapeutic purposes in Asian countries. One of the active ginsenoside metabolites, 20(S)-Protopanaxatriol (PPT), has been associated with diverse pharmacological effects, including anti-inflammatory properties. Although the capacity of PPT as an anti-inflammatory agent has been studied, this study aimed to explore the intrinsic mechanism of PPT in regulating inflammasome activation-mediated inflammatory responses in experimental models. Lipopolysaccharide (LPS)-primed peritoneal macrophages in vitro was used to study the role of PPT on inflammasome activation. LPS-induced septic shock and monosodium urate (MSU)-induced murine peritonitis models were employed for in vivo evaluations. PPT attenuated NLRP3 inflammasome activation and also reduced ASC oligomerization, leading to attenuation of interleukin (IL)-1β secretion. Further, PPT inhibited IL-1β secretion in both LPS-induced septic shock and MSU-induced mouse peritonitis models. This study revealed that ginsenoside metabolite PPT, inhibits inflammation-mediated inflammasome activation and supported the traditional use of ginseng in treating various inflammatory disorders.

Mechanical Circulatory Support in Refractory Vasodilatory Septic Shock: a Randomized Controlled Porcine Study.

As controversy persists regarding the benefits of mechanical circulatory support in septic shock with a predominantly vasoplegic phenotype, preclinical studies may provide a useful alternative to fill the actual knowledge gap. Here, we investigated the physiologic responses to venoarterial extracorporeal membrane oxygenation therapy (VA-ECMO) in a clinically relevant porcine peritonitis-induced model of refractory vasodilatory septic shock. In 12 anesthetized, mechanically ventilated, and instrumented domestic pigs, septic shock was induced by intraperitoneally inoculating autologous feces. After reaching the threshold for refractory vasodilatory shock (norepinephrine dose ≥1 μg/kg/min), the pigs were randomized into the conservative treatment group (control) or the VA-ECMO group (target flow 100 mL/kg/min). The time to develop refractory vasodilatory shock was similar in both groups (18.8 h in the ECMO group, 18.1 h in the control group). There was no difference between the groups in terms of time to death measured from the point of reaching the predefined vasopressor threshold (7.1 h for the ECMO group, 7.9 h for the control group). The initiation of ECMO resulted in a markedly increased fluid and vasopressor support. Although treatment with ECMO compromised neither renal nor carotid blood flow initially, both progressively decreased later during the experiment. The pattern of sepsis-induced multiorgan injury, alterations in energy metabolism, and the systemic inflammatory response were remarkably similar between both groups. In conclusion, the application of VA-ECMO in this model of peritonitis-induced refractory vasodilatory septic shock aggravated hemodynamic deterioration. Our findings contribute to increasing equipoise with respect to the clinical utility of VA-ECMO in refractory vasodilatory shock.

Thiazolidine-2,4-dione-based irreversible allosteric IKK-β kinase inhibitors: Optimization into in vivo active anti-inflammatory agents

Selective kinase inhibitors development is a cumbersome task because of ATP binding sites similarities across kinases. On contrast, irreversible allosteric covalent inhibition offers opportunity to develop novel selective kinase inhibitors. Previously, we reported thiazolidine-2,4-dione lead compounds eliciting in vitro irreversible allosteric inhibition of IKK-β. Herein, we address optimization into in vivo active anti-inflammatory agents. We successfully developed potent IKK-β inhibitors with the most potent compound eliciting IC50 = 0.20 μM. Cellular assay of a set of active compounds using bacterial endotoxin lipopolysaccharide (LPS)-stimulated macrophages elucidated significant in vitro anti-inflammatory activity. In vitro evaluation of microsomal and plasma stabilities showed that the promising compound 7a is more stable than compound 7p. Finally, in vivo evaluation of 7a, which has been conducted in a model of LPS-induced septic shock in mice, showed its ability to protect mice against septic shock induced mortality. Accordingly, this study presents compound 7a as a novel potential irreversible allosteric covalent inhibitor of IKK-β with verified in vitro and in vivo anti-inflammatory activity.

Antiseptic Effect of Ps-K18: Mechanism of Its Antibacterial and Anti-Inflammatory Activities.

Recently, bioactive peptides have attracted attention for their therapeutic applications in the pharmaceutical industry. Among them, antimicrobial peptides are candidates for new antibiotic drugs. Since pseudin-2 (Ps), isolated from the skin of the paradoxical frog Pseudis paradoxa, shows broad-spectrum antibacterial activity with high cytotoxicity, we previously designed Ps-K18 with a Lys substitution for Leu18 in Ps, which showed high antibacterial activity and low toxicity. Here, we examined the potency of Ps-K18, aiming to develop antibiotics derived from bioactive peptides for the treatment of Gram-negative sepsis. We first investigated the antibacterial mechanism of Ps-K18 based on confocal micrographs and field emission scanning electron microscopy, confirming that Ps-K18 targets the bacterial membrane. Anti-inflammatory mechanism of Ps-K18 was investigated by secreted alkaline phosphatase reporter gene assays and RT-PCR, which revealed that Ps-K18 activates innate defense via Toll-like receptor 4-mediated nuclear factor-kappa B signaling pathways. Moreover, we investigated the antiseptic effect of Ps-K18 using a lipopolysaccharide or Escherichia coli K1-induced septic shock mouse model. Ps-K18 significantly reduced bacterial growth and inflammatory responses in the septic shock model. Ps-K18 showed low renal and liver toxicity and attenuated lung damage effectively. This study suggests that Ps-K18 is a potent peptide antibiotic that could be applied therapeutically to Gram-negative sepsis.

IMPACT OF EXOGENOUS APELINERGICS ON METABOLIC DYSFUNCTION IN EXPERIMENTAL SEPTIC HEARTS

ELABELA (ELA) and Apelin-13 (APL-13) bind to the apelin receptor (APJ), a GPCR highly expressed in the cardiovascular system. Those are the strongest known endogenous inotropic and dominant apelinergic ligands in human heart which improve heart performance during sepsis. Apelins (APL) have been also clearly committed in improving insulin sensitivity and glucose handling, including in the heart. The purpose of this study was to establish the metabolic profile and the impact of APL infusion in an experimental model of rat septic shock.

The effects of scopolamine on the survival time and microcirculation of septic shock rats

Introduction: Shock has been established as a disorder of the microcirculation. Despite various treatments, the mortality rate of infectious shocks remains 30–50%. The study was designed to explore the effects of scopolamine on the survival time, microcirculation and inflammatory cytokine secretion in rats with septic shock.Methods: SD rats were randomly divided into seven groups: a sham group, a control group, a saline group and four scopolamine group. The rat septic shock model was induced by cecal ligation, perforation and drainage, while the operation in the sham group involved opening and closing the abdominal cavity. The survival time was recorded to determine a suitable dose for the subsequent experiments. The microcirculation of the terminal ileum was observed. The concentrations of IL-10, IL-6 and TNF-α in the plasma and lungs were detected by ELISA, and the wet-dry ratio of the lung was calculated.Results: Compared to the control and saline group, the septic shock rats treated in the scopolamine group had a longer survival time, a lower reduction in arteriolar blood flow, and a decreased change in the average diameter of arterioles and venules. The rat wet–dry lung ratio was less in the sham, control and scopolamine groups compared to the saline group. The plasma and lung cytokine concentrations of the rats belonging to the scopolamine group were less than those of the control and saline groups; however, all of the cytokine concentrations were higher than those of the sham group.Conclusions: Scopolamine reduced the plasma and lung concentrations of specific cytokines, improved the function of the microcirculation and prolonged the survival time of rats with septic shock.

Mouse Models of Sepsis and Septic Shock

Mouse Models of Sepsis and Septic Shock

High mobility group box protein 1 neutralization therapy in ovine bacteremia: Lessons learned from an ovine septic shock model incorporating intensive care support.

Sepsis is a highly complex and often fatal syndrome which varies widely in its clinical manifestations, and therapies that target the underlying uncontrolled immune status in sepsis are needed. The failure of preclinical approaches to provide significant sepsis survival benefit in the clinic is often attributed to inappropriate animal disease models. It has been demonstrated that high mobility group box protein 1 (HMGB1) blockade can reduce inflammation, mortality and morbidity in experimental sepsis without promoting immunosuppression. Within this study, we explored the use of ovine anti-HMGB1 antibodies in a model of ovine septic shock incorporating intensive care supports (OSSICS). Results: Septic sheep exhibited elevated levels of HMGB1 within 12 h after the induction of sepsis. In this study, sepsis was induced in six anaesthetized adult Border Leicester × Merino ewes via intravenous instillation of E. coli and sheep monitored according to intensive care unit standard protocols for 26 h, with the requirement for noradrenaline as the primary endpoint. Septic sheep exhibited a hyperdynamic circulation, renal dysfunction, deranged coagulation profile and severe metabolic acidosis. Sheep were assigned a severity of illness score, which increased over time. While a therapeutic effect of intravenous anti-HMGB1 antibody could not be observed in this model due to limited animal numbers, a reduced bacterial dose induced a septic syndrome of much lower severity. With modifications including a reduced bacterial dose, a longer timeframe and broad spectrum antibiotics, the OSSICS model may become a robust tool for preclinical assessment of sepsis therapeutics.

Toll-like receptor mediated inflammation requires FASN-dependent MYD88 palmitoylation.

Toll-like receptor (TLR)/myeloid differentiation primary response protein (MYD88) signaling aggravates sepsis by impairing neutrophil migration to infection sites. However, the role of intracellular fatty acids in TLR/MYD88 signaling is unclear. Here, inhibition of fatty acid synthase by C75 improved neutrophil chemotaxis and increased the survival of mice with sepsis in cecal ligation puncture and lipopolysaccharide-induced septic shock models. C75 specifically blocked TLR/MYD88 signaling in neutrophils. Treatment with GSK2194069 that targets a different domain of fatty acid synthase, did not block TLR signaling or MYD88 palmitoylation. De novo fatty acid synthesis and CD36-mediated exogenous fatty acid incorporation contributed to MYD88 palmitoylation. The binding of IRAK4 to the MYD88 intermediate domain and downstream signal activation required MYD88 palmitoylation at cysteine 113. MYD88 was palmitoylated by ZDHHC6, and ZDHHC6 knockdown decreased MYD88 palmitoylation and TLR/MYD88 activation upon lipopolysaccharide stimulus. Thus, intracellular saturated fatty acid-dependent palmitoylation of MYD88 by ZDHHC6 is a therapeutic target of sepsis.

Protective effects of glucocorticoid on liver injury in a rat sepsis model.

Sepsis is one of the leading causes of death with unsatisfactory current treatments. The present study assessed the liver protective effect of glucocorticoids on different levels of inflammation in septic shock rats. A rat septic shock model was established by lipopolysaccharide (LPS) injection. Rats were divided into control (Control), high-inflammation treated with hydrocortisone (HT), high-inflammation non-treatment (HNT), low-inflammation treated with hydrocortisone (LT) and low-inflammation non-treatment (LNT) groups according to the levels of serum C-reactive protein (CRP), interleukin (IL)-6 and interferon (IFN)-γ. The mean arterial pressure and heart rate changes were continuously monitored and aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were measured by an automatic biochemical analyzer. Hematoxylin and eosin (H&E) staining was performed to observe the pathological changes of liver tissue. Western blot analysis was used to detect the expression of p38 mitogen-activated protein kinase (MAPK) and NF-κB protein. The results demonstrated that following 7 days of treatment, there were no obvious differences in the serum CRP, IL-6 and IFN-γ levels between the HT group and the control group, whilst the HNT group, LT group and LNT group were significantly different compared with the HT and control groups. H&E staining demonstrated that the liver cells in the HT group were homogeneous following 7 days of treatment. Western blot analysis determined that the phosphorylation levels of p38MAPK and NF-κB in HT group were reduced significantly compared with the LT group, while there was no obvious difference with the control group after 7 days treatment. The present results indicated that glucocorticoids have better therapeutic effect on septic shock rats with high-inflammation compared with low-inflammation rats. The present study provides a novel approach for glucocorticoid treatment of septic shock.

Characterization of Long Noncoding RNA and mRNA Profiles in Sepsis-Induced Myocardial Depression

Septic shock with heart dysfunction is very common in intensive care units. However, whether long noncoding RNA (lncRNA) and mRNA profiles differ between patients with and without myocardial depression is unknown. We generated rat models of hypodynamic septic shock induced by lipopolysaccharide. A total of 12 rat models was constructed and heart tissue from each was collected. Whole genomic RNA sequencing was performed on left ventricular tissue; 6,508 novel lncRNAs and 432 annotated lncRNAs were identified in heart samples, and 74 lncRNAs were expressed differently in the sepsis and control groups. Gene ontology term enrichment indicated apoptosis and its related pathways showed obvious enrichment, which suggested cell apoptosis could play a critical role in the process of myocardial depression. Furthermore, we focused on one lncRNA from the Pvt1 gene. By silencing this lncRNA, we demonstrated knockdown of Pvt1 expression could induce cell apoptosis in lipopolysaccharide-induced heart cells, through increasing the expression of c-Myc, Bid, Bax, and caspase-3 and decreasing the expression of Myd88 and Bcl-2, thereby proving its functional role in myocardial depression. These results demonstrate that lncRNAs both participate in and mediate the pathological process of myocardial depression. Our study improves the understanding of the basic molecular mechanisms underlying myocardial depression.

IRF1 and IRF2 regulate the non-canonical inflammasome.

The non-canonical inflammasome mediates pyroptotic cell death in response to bacterial lipopolysaccharide (LPS) found in the cytosol. Understanding the mechanism and regulation of this system is of great interest, given its central role in mouse models of bacterial septic shock. In this issue of EMBO Reports, Benaoudia and colleagues sought to discover extra players in the human non-canonical inflammasome using a CRISPR library screen; the only strongly positive hit apart from the known components caspase-4 and gasdermin D was interferon regulatory factor-2 (IRF2) [1 ]. IRF2 was found to be a transcriptional activator of caspase-4, and in its absence, induction of IRF1 could substitute to maintain caspase-4 expression.

Characterization of Circular RNA and microRNA Profiles in Septic Myocardial Depression: a Lipopolysaccharide-Induced Rat Septic Shock Model.

Septic shock with heart dysfunction is common in intensive care units. However, the mechanism underlying myocardial depression is still unclear. Whether circular RNA (circRNA) or microRNA (miRNA) profiles differ between patients with and without myocardial depression is unknown. We generated a hypodynamic septic shock model induced by lipopolysaccharide (LPS) in adolescent rats. A total of 12 rats were utilized and heart tissue from each was collected. RNA sequencing was performed on left ventricular tissue. We focused on features of circRNAs and miRNAs, predicting their function by bioinformatic analysis and constructing circRNA-associated and miRNA-associated regulatory networks in heart tissue. We detected 851 circRNAs in heart samples, and 11 showed differential expression. A total of 639 annotated miRNAs and 91 novel miRNAs were explored including 78 showing differential expression between the two groups. We then constructed the most comprehensive circRNA-associated and miRNA-associated networks to explore their regulatory relationship in septic heart tissue, and demonstrated that different networks could potentially participate in and regulate the pathological process of sepsis. Furthermore, gene ontology term enrichment indicated miRNAs, and miRNA-mRNA networks could be associated with regulation and metabolic process, or influence cellular functions. The construction of regulator networks could improve the understanding of the basic molecular mechanisms underlying myocardial depression. It will be important for future investigations to ascertain the biological mechanisms present during the development of sepsis-induced myocardial depression to influence approaches to treatment.

MicroTools enables automated quantification of capillary density and red blood cell velocity in handheld vital microscopy

Direct assessment of capillary perfusion has been prioritized in hemodynamic management of critically ill patients in addition to optimizing blood flow on the global scale. Sublingual handheld vital microscopy has enabled online acquisition of moving image sequences of the microcirculation, including the flow of individual red blood cells in the capillary network. However, due to inherent content complexity, manual image sequence analysis remained gold standard, introducing inter-observer variability and precluding real-time image analysis for clinical therapy guidance. Here we introduce an advanced computer vision algorithm for instantaneous analysis and quantification of morphometric and kinetic information related to capillary blood flow in the sublingual microcirculation. We evaluated this technique in a porcine model of septic shock and resuscitation and cardiac surgery patients. This development is of high clinical relevance because it enables implementation of point-of-care goal-directed resuscitation procedures based on correction of microcirculatory perfusion in critically ill and perioperative patients.

The cAMP Pathway Amplifies Early MyD88-Dependent and Type I Interferon-Independent LPS-Induced Interleukin-10 Expression in Mouse Macrophages

Interleukin-10 (IL-10) is a key anti-inflammatory cytokine, secreted by macrophages and other immune cells to attenuate inflammation. Autocrine type I interferons (IFNs) largely mediate the delayed expression of IL-10 by LPS-stimulated macrophages. We have previously shown that IL-10 is synergistically expressed in macrophages following a costimulus of a TLR agonist and cAMP. We now show that the cAMP pathway directly upregulates IL-10 transcription and plays an important permissive and synergistic role in early, but not late, LPS-stimulated IL-10 mRNA and protein expression in mouse macrophages and in a mouse septic shock model. Our results suggest that the loss of synergism is not due to desensitization of the cAMP inducing signal, and it is not mediated by a positive crosstalk between the cAMP and type I IFN pathways. First, cAMP elevation in LPS-treated cells decreased the secretion of type I IFN. Second, autocrine/paracrine type I IFNs induce IL-10 promoter reporter activity only additively, but not synergistically, with the cAMP pathway. IL-10 promoter reporter activity was synergistically induced by cAMP elevation in macrophages stimulated by an agonist of either TLR4, TLR2/6, or TLR7, receptors which signal via MyD88, but not by an agonist of TLR3 which signals independently of MyD88. Moreover, MyD88 knockout largely reduced the synergistic IL-10 expression, indicating that MyD88 is required for the synergism displayed by LPS with cAMP. This report delineates the temporal regulation of early cAMP-accelerated vs. late type I IFN-dependent IL-10 transcription in LPS-stimulated murine macrophages that can limit inflammation at its onset.

A Mathematical Model of dP/dt Max for the Evaluation of the Dynamic Control of Heart Contractility in Septic Shock

Septic shock (SS) patients often show elevated heart rate (HR) despite resuscitation, and this condition is considered an early manifestation of myocardial dysfunction due to an impairment of autonomic nervous system (ANS). We aimed at proposing a mathematical model to assess the autonomic control of ventricular contractility (VC) and HR to track changes in heart functionality during an experimental animal model of SS and resuscitation. SS was induced in six adult swine by polymicrobial peritonitis. We analyzed the beat-to-beat variability of the maximum positive time derivative of left ventricular pressure (dP/dt max), heart period (HP), and aortic blood pressure (ABP). We identified the transfer functions relating fluctuations in ABP and HP to dP/dt max to characterize the static and dynamic properties of the arterial baroreflex and the force-frequency relation mechanisms, respectively. Standard indices of autonomic dysfunction have also been considered as HR variability (HRV) and baroreflex sensitivity (BRS). During baseline, the baroreflex is predominant in controlling VC with a gain value of -5.8 (-7.5,-3) s-1, compared to -1.2 (-1.9,-0.5) mmHg/s ms-1 of the force-frequency autoregulation. During shock, both mechanisms increase their extent in VC control (higher gains and slightly faster dynamics for the baroreflex). After resuscitation, the physiological control of VC is not restored and all the animals still exhibit high HR and reduced HRV and BRS. A condition of cardiovascular inefficiency is persistent after resuscitation and this could be due to autonomic dysfunction. The ANS in SS is crucial to restore homeostasis. Our model could be used to evaluate the efficacy of treatments on VC and related control mechanisms.

Mathematical modeling of septic shock based on clinical data

BackgroundMathematical models of diseases may provide a unified approach for establishing effective treatment strategies based on fundamental pathophysiology. However, models that are useful for clinical practice must overcome the massive complexity of human physiology and the diversity of patients’ environmental conditions. With the aim of modeling a complex disease, we choose sepsis, which is highly complex, life-threatening systemic disease with high mortality. In particular, we focused on septic shock, a subset of sepsis in which underlying circulatory and cellular/metabolic abnormalities are profound enough to substantially increase mortality. Our model includes cardiovascular, immune, nervous system models and a pharmacological model as submodels and integrates them to create a sepsis model based on pathological facts.ResultsModel validation was done in two steps. First, we established a model for a standard patient in order to confirm the validity of our approach in general aspects. For this, we checked the correspondence between the severity of infection defined in terms of pathogen growth rate and the ease of recovery defined in terms of the intensity of treatment required for recovery. The simulations for a standard patient showed good correspondence. We then applied the same simulations to a patient with heart failure as an underlying disease. The model showed that spontaneous recovery would not occur without treatment, even for a very mild infection. This is consistent with clinical experience.We next validated the model using clinical data of three sepsis patients. The model parameters were tuned for these patients based on the model for the standard patient used in the first part of the validation. In these cases, the simulations agreed well with clinical data. In fact, only a handful parameters need to be tuned for the simulations to match with the data.ConclusionsWe have constructed a model of septic shock and have shown that it can reproduce well the time courses of treatment and disease progression. Tuning of model parameters for each patient could be easily done. This study demonstrates the feasibility of disease models, suggesting the possibility of clinical use in the prediction of disease progression, decisions on the timing of drug dosages, and the estimation of time of infection.

3389 Coagulation Factor Xll-mediated contact system and its role in adaptive and innate immune cell movement

OBJECTIVES/SPECIFIC AIMS: The objectives of this study are to 1) expand upon the paradigm of HK-D5 accelerated immune cell chemotaxis; 2) characterize the role of FXII in murine models of immune-mediated disease using FXII KO mice and a small molecule inhibitor of FXIIa. METHODS/STUDY POPULATION: To test whether the addition of HK-D5 peptide would accelerate C-C chemokine receptor type 2 (CCR2)-mediated chemotaxis in vitro, a real-time transwell chemotaxis assay was developed utilizing human THP-1 monocyte cell line (Fig 1). For in vivo studies, both pharmacologic FXIIa antagonism and FXll KO mice were used. Genotyping, histopathological review, FXll protein expression, and active partial thromboplastin time (aPTT) measurements were used to phenotypically characterize FXII KO mice compared to C57BL/6 wild type mice (Fig 2). Subsequently, the FXll KO mice were studied in varied models of immune-mediated disease, including LPS-induced sepsis and experimental autoimmune encephalitis (EAE), to see if and how the absence of FXll can mitigate disease severity. The EAE model involved active immunization with myelin oligodendrocyte glycoprotein (MOG) and measurement of established clinical disease severity scores. The LPS sepsis model involved an intraperitoneal injection of LPS followed by 48-hour monitoring of core body temperature using subdermal temperature transponders as a proxy for inflammatory events related to septic shock (Fig 3). RESULTS/ANTICIPATED RESULTS: HK-D5 significantly accelerates CCR2-mediated chemotaxis compared to chemokine alone (p = 0.001) similar to HK-D5’s ability to accelerate CCR7-mediated chemotaxis as previously established. The FXll KO mice were backcrossed to the C57BL/6J background and confirmed by genotyping and complete absence of FXII protein in plasma. Compared to the control, FXII KO mice have a significantly prolonged aPTT without evidence of bleeding abnormalities, which confirms the expected phenotype previously described and recapitulates what is observed in Factor XII deficiency in humans. KO mice showed no significant gross or histopathological differences in secondary lymphoid structures compared to the control. Immunohistochemistry confirmed well-organized lymphoid structures with intact B- and T-cell populations. FXll KO mice are protected in LPS-induced septic shock and EAE models. Regarding the EAE model, FXIIa inhibition significantly reduced disease severity compared to control. In the LPS model, FXll KO mice recover within 24 hours after LPS-challenge measured subjectively and objectively by core body temperature measurement. DISCUSSION/SIGNIFICANCE OF IMPACT: The current study and previous findings suggest a novel immune signaling mechanism by which a peptide fragment of high molecular-weight kininogen (HK-D5) acts as an accelerant of both innate and adaptive immune cell chemotaxis in multiple immune contexts. This has broad implications regarding a mechanism of immune-mediated inflammation in a variety of disease states, which might be amenable to the targeting this pathway for therapeutic intent.