Primary granule release from human neutrophils is potentiated by soluble fibrinogen through a mechanism depending on multiple intracellular signaling pathways

Anti-inflammatory Effect of Batroxobin Combined With Anticoagulation in Patients With Cerebral Venous Thrombosis

Inflammation is pivotal in the pathogenesis and development of cerebral venous thrombosis (CVT). Herein, we aimed to assess the anti-inflammatory effects of batroxobin combined with anticoagulation in CVT. Participants were categorized into the batroxobin group (batroxobin combined with anticoagulation) and the control group (anticoagulation only). Regression analysis was employed to explore the association between the number of episodes of batroxobin administration and the fluctuation of inflammatory indicators, as well as the proportion of patients with inflammatory indicators that were reduced after batroxobin use. Twenty-three cases (age: 39.9 ± 13.8 years, female: 39.1%) in the batroxobin group and 36 cases (40.3 ± 9.6 years, 52.8%) in the control group were analyzed. Compared to the control group, batroxobin combined with anticoagulation significantly decreased fibrinogen (P < .001), platelet-lymphocyte ratio (PLR) (P = .016) and systemic immune-inflammation index (SII) (P = .008), and increased the proportion of the patients with lower fibrinogen (P < .001), neutrophil-lymphocyte ratio (NLR) (P = .005), PLR (P = .026), and SII (P = .006). Linear analysis showed that as the number of episodes of batroxobin administration increased, the fibrinogen (P < .001), the PLR (P = .001), and the SII (P = .020) significantly decreased. Logistic regression analysis showed as the number of episodes of batroxobin administration increased, the ratio of the patients with decreased NLR (P = .008) and PLR (P = .015), as well as SII (P = .013), significantly increased. Batroxobin could decrease NLR, PLR, and SII in CVT. The effect was related to the number of episodes of batroxobin administration. Besides reducing fibrinogen and indirect thrombolysis effects, this may be another critical benefit of batroxobin for CVT.

Predictive Factors for Difficult Laparoscopic Cholecystectomies in Acute Cholecystitis

Laparoscopic cholecystectomy (LC) is the gold standard treatment in acute cholecystitis. However, one in six cases is expected to be difficult due to intense inflammation and suspected adherence to and involvement of adjacent important structures, which may predispose patients to higher risk of vascular and biliary injuries. In this study, we aimed to identify the preoperative parameters with predictive value for surgical difficulties. A retrospective study of 255 patients with acute cholecystitis admitted in emergency was performed between 2019 and 2023. Patients in the difficult laparoscopic cholecystectomy (DLC) group experienced more complications compared to the normal LC group (33.3% vs. 15.3%, p < 0.001). Age (p = 0.009), male sex (p = 0.03), diabetes (p = 0.02), delayed presentation (p = 0.03), fever (p = 0.004), and a positive Murphy sign (p = 0.007) were more frequently encountered in the DLC group. Total leukocytes, neutrophils, and the neutrophil-to-lymphocyte ratio (NLR) were significantly higher in the DLC group (p < 0.001, p = 0.001, p = 0.001 respectively). The Tongyoo score (AUC ROC of 0.856) and a multivariate model based on serum fibrinogen, thickness of the gallbladder wall, and transverse diameter of the gallbladder (AUC ROC of 0.802) showed a superior predictive power when compared to independent parameters. The predictive factors for DLC should be assessed preoperatively to optimize the therapeutic decision.

High Fibrinogen to Albumin Ratio: A Novel Marker for Risk of Stroke-Associated Pneumonia?

Background: Stroke-associated pneumonia (SAP) is associated with poor prognosis after acute ischemic stroke (AIS).

Purpose: This study aimed to describe the parameters of coagulation function and evaluate the association between the fibrinogen-to-albumin ratio (FAR) and SAP in patients with AIS.

Patients and methods: A total of 932 consecutive patients with AIS were included. Coagulation parameters were measured at admission. All patients were classified into two groups according to the optimal cutoff FAR point at which the sum of the specificity and sensitivity was highest. Propensity score matching (PSM) was performed to balance potential confounding factors. Univariate and multivariate logistic regression analyses were applied to identify predictors of SAP.

Results: A total of 100 (10.7%) patients were diagnosed with SAP. The data showed that fibrinogen, FAR, and D-dimer, prothrombin time (PT), activated partial thromboplastin time (aPTT) were higher in patients with SAP, while albumin was much lower. Patients with SAP showed a significantly increased FAR when compared with non-SAP (P < 0.001). Patients were assigned to groups of high FAR (≥0.0977) and low FAR (<0.0977) based on the optimal cut-off value. Propensity score matching analysis further confirmed the association between FAR and SAP. After adjusting for confounding and risk factors, multivariate regression analysis showed that the high FAR (≥0.0977) was an independent variable predicting the occurrence of SAP (odds ratio =2.830, 95% CI = 1.654–4.840, P < 0.001). In addition, the FAR was higher in the severe pneumonia group when it was assessed by pneumonia severity index (P = 0.008).

Conclusions: High FAR is an independent potential risk factor of SAP, which can help clinicians identify high-risk patients with SAP after AIS.

The Role of Fibrin(ogen) in Wound Healing and Infection Control

Fibrinogen, one of the most abundant plasma proteins playing a key role in hemostasis, is an important modulator of wound healing and host defense against microbes. In the current review, we address the role of fibrin(ogen) throughout the process of wound healing and subsequent tissue repair. Initially fibrin(ogen) acts as a provisional matrix supporting incoming leukocytes and acting as reservoir for growth factors. It later goes on to support re-epithelialization, angiogenesis, and fibroplasia. Importantly, removal of fibrin(ogen) from the wound is essential for wound healing to progress. We also discuss how fibrin(ogen) functions through several mechanisms to protect the host against bacterial infection by providing a physical barrier, entrapment of bacteria in fibrin(ogen) networks, and by directing immune cell function. The central role of fibrin(ogen) in defense against bacterial infection has made it a target of bacterial proteins, evolved to interact with fibrin(ogen) to manipulate clot formation and degradation for the purpose of promoting microbial virulence and survival. Further understanding of the dual roles of fibrin(ogen) in wound healing and infection could provide novel means of therapy to improve recovery from surgical or chronic wounds and help to prevent infection from highly virulent bacterial strains, including those resistant to antibiotics.

Thrombin-Fibrin(ogen) Interactions, Host Defense and Risk of Thrombosis

Fibrinogen is a well-known risk factor for arterial and venous thrombosis. Its function is not restricted to clot formation, however, as it partakes in a complex interplay between thrombin, soluble plasma fibrinogen, and deposited fibrin matrices. Fibrinogen, like thrombin, participates predominantly in hemostasis to maintain vascular integrity, but executes some important pleiotropic effects: firstly, as observed in thrombin generation experiments, fibrin removes thrombin from free solution by adsorption. The adsorbed thrombin is protected from antithrombins, notably α2-macroglobulin, and remains physiologically active as it can activate factors V, VIII, and platelets. Secondly, immobilized fibrinogen or fibrin matrices activate monocytes/macrophages and neutrophils via Mac-1 interactions. Immobilized fibrin(ogen) thereby elicits a pro-inflammatory response with a reciprocal stimulating effect of the immune system on coagulation. In contrast, soluble fibrinogen prohibits recruitment of these immune cells. Thus, while fibrin matrices elicit a procoagulant response, both directly by protecting thrombin and indirectly through the immune system, high soluble fibrinogen levels might protect patients due to its immune diminutive function. The in vivo influence of the 'protective' plasma fibrinogen versus the 'pro-thrombotic' fibrin matrices on thrombosis should be explored in future research.

Role of the coagulation system in the pathogenesis of sickle cell disease

Sickle cell disease (SCD) is an inherited monogenic red blood cell disorder affecting millions worldwide. SCD causes vascular occlusions, chronic hemolytic anemia, and cumulative organ damage such as nephropathy, pulmonary hypertension, pathologic heart remodeling, and liver necrosis. Coagulation system activation, a conspicuous feature of SCD that causes chronic inflammation, is an important component of SCD pathophysiology. The key coagulation factor, thrombin (factor IIa [FIIa]), is both a central protease in hemostasis and thrombosis and a key modifier of inflammation. Pharmacologic or genetic reduction of circulating prothrombin in Berkeley sickle mice significantly improves survival, ameliorates vascular inflammation, and results in markedly reduced end-organ damage. Accordingly, factors both upstream and downstream of thrombin, such as the tissue factor-FX complex, fibrinogen, platelets, von Willebrand factor, FXII, high-molecular-weight kininogen, etc, also play important roles in SCD pathogenesis. In this review, we discuss the various aspects of coagulation system activation and their roles in the pathophysiology of SCD.

The multifaceted role of fibrinogen in tissue injury and inflammation

The canonical role of the hemostatic and fibrinolytic systems is to maintain vascular integrity. Perturbations in either system can prompt primary pathological end points of hemorrhage or thrombosis with vessel occlusion. However, fibrin(ogen) and proteases controlling its deposition and clearance, including (pro)thrombin and plasmin(ogen), have powerful roles in driving acute and reparative inflammatory pathways that affect the spectrum of tissue injury, remodeling, and repair. Indeed, fibrin(ogen) deposits are a near-universal feature of tissue injury, regardless of the nature of the inciting event, including injuries driven by mechanical insult, infection, or immunological derangements. Fibrin can modify multiple aspects of inflammatory cell function by engaging leukocytes through a variety of cellular receptors and mechanisms. Studies on the role of coagulation system activation and fibrin(ogen) deposition in models of inflammatory disease and tissue injury have revealed points of commonality, as well as context-dependent contributions of coagulation and fibrinolytic factors. However, there remains a critical need to define the precise temporal and spatial mechanisms by which fibrinogen-directed inflammatory events may dictate the severity of tissue injury and coordinate the remodeling and repair events essential to restore normal organ function. Current research trends suggest that future studies will give way to the identification of novel hemostatic factor-targeted therapies for a range of tissue injuries and disease.

Fibrinogen Is at the Interface of Host Defense and Pathogen Virulence in Staphylococcus aureus Infection

Fibrinogen not only plays a pivotal role in hemostasis but also serves key roles in antimicrobial host defense. As a rapidly assembled provisional matrix protein, fibrin(ogen) can function as an early line of host protection by limiting bacterial growth, suppressing dissemination of microbes to distant sites, and mediating host bacterial killing. Fibrinogen-mediated host antimicrobial activity occurs predominantly through two general mechanisms, namely, fibrin matrices functioning as a protective barrier and fibrin(ogen) directly or indirectly driving host protective immune function. The potential of fibrin to limit bacterial infection and disease has been countered by numerous bacterial species evolving and maintaining virulence factors that engage hemostatic system components within vertebrate hosts. Bacterial factors have been isolated that simply bind fibrinogen or fibrin, promote fibrin polymer formation, or promote fibrin dissolution. Staphylococcus aureus is an opportunistic gram-positive bacterium, the causative agent of a wide range of human infectious diseases, and a prime example of a pathogen exquisitely sensitive to host fibrinogen. Indeed, current data suggest fibrinogen serves as a context-dependent determinant of host defense or pathogen virulence in Staphylococcus infection whose ultimate contribution is dictated by the expression of S. aureus virulence factors, the path of infection, and the tissue microenvironment.

TREM-like transcript 2 is stored in human neutrophil primary granules and is up-regulated in response to inflammatory mediators

The triggering receptor expressed on myeloid cell locus encodes a family of receptors that is emerging as an important class of molecules involved in modulating the innate immune response and inflammation. Of the 4 conserved members, including triggering receptor expressed on myeloid cells 1 and 2 and triggering receptor expressed on myeloid cell-like transcripts 1 and 2, relatively little is known about triggering receptor expressed on myeloid cell-like transcript 2 expression and function, particularly in humans. In this study, experiments were performed to determine if triggering receptor expressed on myeloid cell-like transcript 2 expression is conserved between mouse and human, demonstrating that human triggering receptor expressed on myeloid cell-like transcript 2 is expressed on cells of the lymphoid, as well as myeloid/granuloid lineages, similar to murine triggering receptor expressed on myeloid cell-like transcript 2. Consistent with studies in the mouse, triggering receptor expressed on myeloid cell-like transcript 2 expression is up-regulated in response to inflammatory mediators on human neutrophils. Importantly, it was shown that triggering receptor expressed on myeloid cell-like transcript 2, in resting human neutrophils, is predominantly localized to intracellular vesicles, including secretory vesicles and primary granules; with the majority of triggering receptor expressed on myeloid cell-like transcript 2 stored in primary granules. In contrast to other primary granule proteins, triggering receptor expressed on myeloid cell-like transcript 2 is not expelled on neutrophil extracellular traps but is retained in the plasma membrane following primary granule exocytosis. In summary, these findings establish that triggering receptor expressed on myeloid cell-like transcript 2 expression is conserved between species and is likely to be important in regulating neutrophil antimicrobial function following primary granule exocytosis.

Poly(ethylene glycol)-containing hydrogels promote the release of primary granules from human blood-derived polymorphonuclear leukocytes

Polymorphonuclear leukocytes (PMNs) are recruited to sites of injury and biomaterial implants. Once activated, PMNs can exocytose their granule subsets to recruit monocytes (MCs) and mediate MC/macrophage activation. We investigated the release of myeloperoxidase (MPO), a primary granule marker, and matrix metalloproteinase-9 (MMP-9), a tertiary granule marker, from human blood-derived PMNs cultured on poly(ethylene glycol) (PEG) hydrogels, polydimethylsiloxane (PDMS), tissue culture polystyrene (TCPS) and gelatin-PEG (GP) hydrogels, with and without the presence of the bacterial peptide formyl-Met-Leu-Phe. Supernatants from PMN cultures on PEG-containing hydrogels (i.e., PEG and GP hydrogels) had higher concentrations of MPO than those from PMN cultures on PDMS or TCPS at 2 h. PMNs on all biomaterials released comparable levels of MMP-9 at 2 h, indicating that PMNs cultured on PEG-containing hydrogels have different mechanisms of release for primary and tertiary granules. Src family kinases were involved in the release of MPO from PMNs cultured on PEG hydrogels, TCPS and GP hydrogels and in the release of MMP-9 from PMNs cultured on all four biomaterials. The increased release of primary granules from PMNs on PEG-containing hydrogels did not significantly increase MC chemotaxis, indicating that additional co-effectors in the dynamic inflammatory milieu in vivo modulate PMN-mediated MC recruitment.

Reactive carbonyl compounds (RCCs) cause aggregation and dysfunction of fibrinogen

Fibrinogen is a key protein involved in coagulation and its deposition on blood vessel walls plays an important role in the pathology of atherosclerosis. Although the causes of fibrinogen (fibrin) deposition have been studied in depth, little is known about the relationship between fibrinogen deposition and reactive carbonyl compounds (RCCs), compounds which are produced and released into the blood and react with plasma protein especially under conditions of oxidative stress and inflammation. Here, we investigated the effect of glycolaldehyde on the activity and deposition of fibrinogen compared with the common RCCs acrolein, methylglyoxal, glyoxal and malondialdehyde. At the same concentration (1 mmol/L), glycolaldehyde and acrolein had a stronger suppressive effect on fibrinogen activation than the other three RCCs. Fibrinogen aggregated when it was respectively incubated with glycolaldehyde and the other RCCs, as demonstrated by SDS-PAGE, electron microscopy and intrinsic fluorescence intensity measurements. Staining with Congo Red showed that glycolaldehyde- and acrolein-fibrinogen distinctly formed amyloid-like aggregations. Furthermore, the five RCCs, particularly glycolaldehyde and acrolein, delayed human plasma coagulation. Only glycolaldehyde showed a markedly suppressive effect on fibrinogenesis, none did the other four RCCs when their physiological blood concentrations were employyed, respectively. Taken together, it is glycolaldehyde that suppresses fibrinogenesis and induces protein aggregation most effectively, suggesting a putative pathological process for fibrinogen (fibrin) deposition in the blood.

Binding of Efb from Staphylococcus aureus to fibrinogen blocks neutrophil adherence

In addition to its pivotal role in hemostasis, fibrinogen (Fg) and provisional fibrin matrices play important roles in inflammation and regulate innate immune responses by interacting with leukocytes. Efb (the extracellular fibrinogen-binding protein) is a secreted Staphylococcus aureus protein that engages host Fg and complement C3. However, the molecular details underlying the Efb-Fg interaction and the biological relevance of this interaction have not been determined. In the present study, we characterize the interaction of Efb with Fg. We demonstrate that the Fg binding activity is located within the intrinsically disordered N-terminal half of Efb (Efb-N) and that the D fragment of Fg is the region that mediates Efb-N binding. More detailed studies of the Efb-N-Fg interactions using ELISA and surface plasmon resonance analyses revealed that Efb-N exhibits a much higher affinity for Fg than typically observed with Fg-binding MSCRAMMs (microbial surface components recognizing adhesive matrix molecules), and data obtained from ELISA analyses using truncated Efb-N constructs demonstrate that Efb-N contains two binding sites located within residues 30-67 and 68-98, respectively. Efb-N inhibits neutrophil adhesion to immobilized Fg by binding to Fg and blocking the interaction of the protein with the leukocyte integrin receptor, α(M)β(2). A motif in the Fg γ chain previously shown to be central to the α(M)β(2) interaction was shown to be functionally distinguishable from the Efb-N binding site, suggesting that the Fg-Efb interaction indirectly impedes Fg engagement by α(M)β(2). Taken together, these studies provide insights into how Efb interacts with Fg and suggest that Efb may support bacterial virulence at least in part by impeding Fg-driven leukocyte adhesion events.

On some aspects of the thermodynamic of membrane recycling mediated by fluid phase endocytosis: evaluation of published data and perspectives

The theoretical and experimental description of fluid phase endocytosis (FPE) requires an asymmetry in phospholipid number between the two leaflets of the cell membrane, which provides the biomechanical torque needed to generate membrane budding. Although the motor force behind FPE is defined, its kinetic has yet to be determined. Based on a body of evidences suggesting that the mean surface tension is unlikely to be involved in endocytosis we decided to determine whether the cytosolic hydrostatic pressure could be involved, by considering a constant energy exchanged between the cytosol and the cell membrane. The theory is compared to existing experimental data obtained from FPE kinetic studies in living cells where altered phospholipid asymmetry or changes in the extracellular osmotic pressure have been investigated. The model demonstrates that FPE is dependent on the influx and efflux of vesicular volumes (i.e. vesicular volumes recycling) rather than the membrane tension of cells. We conclude that: (i) a relationship exists between membrane lipid number asymmetry and resting cytosolic pressure and (ii) the validity of Laplace's law is limited to cells incubated in a definite hypotonic regime. Finally, we discuss how the model could help clarifying elusive observations obtained from different fields and including: (a) the non-canonical shuttling of aquaporin in cells, (b) the relationship between high blood pressure and inflammation and (c) the mechanosensitivity of the sodium/proton exchanger.

Interference of alpha-alkyl-substituted pirinixic acid derivatives with neutrophil functions and signalling pathways

Pirinixic acid (Wy-14,643) is an agonist of the peroxisome proliferator-activated receptor (PPAR) subtype alpha exhibiting beneficial effects in various inflammation-related processes in a slow, long-termed fashion. We recently showed that alpha-substituted pirinixic acid derivatives are agonists of PPAR alpha and act as dual inhibitors of 5-lipoxygenase (5-LO, EC 1.13.11.34) and the microsomal prostaglandin E(2) synthase-1 (EC 5.3.99.3). Here, we explored short-term effects of alpha-substituted pirinixic acid derivatives on typical neutrophil functions evoked by the agonist N-formyl-methionyl-leucyl-phenylalanine (fMLP) including leukotriene formation, generation of reactive oxygen species, and release of human leukocyte elastase (EC 3.4.21.37), and we investigated the modulation of related signalling pathways. Pirinixic acid derivatives that are substituted with alkyl residues in alpha-position of the carboxylic group and with a 6-aminoquinoline residue at the pyrimidine moiety cause inhibition of leukotriene formation, reactive oxygen species formation, and leukocyte elastase release in response to fMLP. In parallel, Ca(2+) mobilisation and the phosphorylation (activation) of p38 mitogen-activated protein kinase was significantly reduced, whereas phosphorylation of the extracellular signal-regulated kinase-2 was unaffected. Pirinixic acid itself was not or only marginally active in all these assays. Conclusively, targeted structural modification of pirinixic acid leads to bioactive compounds that display immediate anti-inflammatory properties in human neutrophils with potential therapeutic value.

Neutrophils phagocytose activated platelets in vivo: a phosphatidylserine, P-selectin, and β2 integrin–dependent cell clearance program

Activated platelets express ligands, which are recognized by counterreceptors on neutrophils. Here, we show that the ensuing cell-to-cell interaction programs neutrophil phagocytic function, resulting in activated platelet clearance. Neutrophils that have internalized platelets circulate in the blood of patients with acute myocardial infarction, and the extent of platelet clearance correlates with expression of platelet activation, including P-selectin. Activated platelets injected intravenously in experimental animals are detectable in circulating neutrophils 60 minutes after, and within 3 hours, more than 70% circulating neutrophils have internalized platelets. Platelet clearance comprises 2 events: adhesion to neutrophils, which requires divalent cations and depends on P-selectin, on the P-selectin glycoprotein ligand-1 (PSGL-1), and on the CD11b/CD18 β2 integrin; and internalization, which is abrogated by the phosphatidylserine-binding protein annexin A5. Adhesion to platelets causes neutrophil degranulation and is blocked by antibodies specific for P-selectin and PSGL-1, either in a synthetic medium in vitro or in the whole blood, therefore in the presence of a physiologic array of plasma cofactors and opsonins. The data suggest that the interaction between circulating platelets and neutrophils influences innate immune functions, possibly contributing to regulate vascular inflammation.

Acute Lung Injury:Apoptosis and Signaling Mechanisms

Acute lung injury (ALI) has been documented clinically following several pathological states such as trauma, septic shock and pneumonia. The histopathological characteristics, paired with the production of a number of cellular pro-inflammatory mediators, play a crucial role in the progression of ALI. During ALI, polymorphonuclear neutrophil (PMN)-mediated apoptosis is delayed by macrophages, possibly via effects on the Fas/FasL mediated pathway, leading to the accumulation of these cells at the site of injury and inflammation. The transcriptional regulation of NFκB, CREB, and AP-1 also regulates the pathogenesis of ALI. During sepsis and septic shock, we found evidence of infiltrating leukocytes in the alveolar spaces along with an increased number of TUNEL-positive cells in the lung sections. We also observed an increased expression of TRADD and Bax/Bcl2 ratio at 7 days post-sepsis. In contrast, the NFκB/IκB ratio increased at 1 day post-sepsis. Together, these data provide evidence illustrating the induction of apoptosis in lung tissues subsequent to the onset of polymicrobial sepsis. The results support the concept that the upregulation of apoptosis following lung inflammation plays a crucial role in the development of acute lung injury and related disorders such as ARDS.

The ITGB2 immunomodulatory gene (CD18), enterocolitis, and Hirschsprung's disease

Hirschsprung's disease (HSCR)-associated enterocolitis (HAEC) remains a major contributor to morbidity and mortality associated with HSCR, being sometimes difficult to diagnose in its subclinical form. Its pathogenesis appears to include impaired local defense mechanisms as well as dysfunctional immune response and leukocyte function. In this context, the ITGB2 (CD18) immunomodulation-related gene is a possible candidate in HAEC pathogenesis as it codes for the beta-subunit of leukocyte adhesion molecule lymphocyte function-associated antigen 1, which has an established role in T-cell development and function. ITGB2/CD18 has also been linked to chronic colitis in both human and animal models involving defense mechanisms within colonic mucosa. There is therefore a fairly compelling case for the potential involvement of the ITGB2 (CD18) in HAEC pathogenesis.

AIM

The aim of this study was to investigate the ITGB2 immunomodulatory gene (CD18) in a cohort of patients with HSCR and explore its correlation with enterocolitis.

PATIENTS AND METHODS

Screening for mutations of the ITGB2 (CD18) gene was performed on DNA extracted from colonic tissue samples and whole blood of 33 HSCR patients controlled by analysis of 60 unaffected individuals from the diverse South African population. Polymerase chain reaction amplification was performed, followed by heteroduplex single-strand conformation polymorphism analysis and bidirectional semiautomated DNA sequencing analysis.

RESULTS

Heteroduplex single-strand conformation polymorphism banding patterns of the ITGB2 gene showed variations in 22 HSCR patients (66%), 13 of whom had severe episodes of HAEC, and 6 others had milder symptoms. Of the 13, 6 (46%) had Down's syndrome-associated HSCR. Genetic variations included 1 mutation (D77N), 2 known (V367, V441), and 4 novel polymorphisms (-111T/C, 24G/T, 295G/A, 892A/G). Significant associations were identified in the exon 5' untranslated promotor region (P < .0001), exon 10 (P < .0007), and the 3' untranslated promotor region at 122G/A (P < .0001) and 370 G/T positions (P = .04). Those regions of the gene most frequently associated with HAEC and severe symptoms were those with more than 1 variant identified in the gene.

CONCLUSIONS

This study shows that impaired CD18 leukocyte and T regulatory cell regulation can probably be linked to a genetic (ITGB2) predisposition to HAEC. It furthermore provides a possible genetic link to HAEC patient selection, identifying a potential molecular target.

CXCR1/2 ligands induce p38 MAPK-dependent translocation and release of opioid peptides from primary granules in vitro and in vivo

Polymorphonuclear leukocytes (PMN) can release opioid peptides which bind to opioid receptors on sensory neurons and inhibit inflammatory pain. This release can be triggered by chemokine receptor 1/2 (CXCR1/2) ligands. Our aim was to identify the granule subpopulation containing opioid peptides and to assess whether MAPK mediate the CXCR1/2 ligand-induced release of these peptides. Using double immunofluorescence confocal microscopy, we showed that beta-endorphin (END) and Met-enkephalin (ENK) were colocalized with the primary (azurophil) granule markers CD63 and myeloperoxidase (MPO) within PMN. END and ENK release triggered by a CXCR1/2 ligand in vitro was dependent on the presence of cytochalasin B (CyB) and on p38 MAPK, but not on p42/44 MAPK. In addition, translocation of END and ENK containing primary granules to submembranous regions of the cell was abolished by the p38 MAPK inhibitor SB203580. In vivo CXCL2/3 reduced pain in rats with complete Freund's adjuvant (CFA)-induced hindpaw inflammation. This effect was attenuated by intraplantar (i.pl.) antibodies against END and ENK and by i.pl. p38 MAPK inhibitor treatment. Taken together, these findings indicate that END and ENK are contained in primary granules of PMN, and that CXCR1/2 ligands induce p38-dependent translocation and release of these opioid peptides to inhibit inflammatory pain.

Fibrin and fibrinolysis in infection and host defense

Bacterial pathogens have frequently evolved and maintained the capacity to engage and/or activate hemostatic system components of their vertebrate hosts. Recent studies of mice with selected alterations in host plasminogen and other hemostatic factors have begun to reveal a seminal role of bacterial plasminogen activators and fibrin clearance in microbial pathogenesis. Bacterial pathogens appear to exploit host plasmin-mediated proteolysis to both support microbial dissemination and evade innate immune surveillance systems. The contribution of bacterial plasminogen activation to the evasion of the inflammatory response is particularly conspicuous with the plague agent, Yersinia pestis. Infection of control mice with wild-type Y. pestis leads to the formation of widespread foci containing massive numbers of free bacteria with little inflammatory cell infiltrate, whereas the loss of either the bacterial plasminogen activator, Pla, or the elimination of host plasminogen results in the accumulation of robust inflammatory cell infiltrates at sites of infection and greatly improved survival. Interestingly, fibrin(ogen) deficiency undermines the local inflammatory response observed with Pla-deficient Y. pestis and effectively eliminates the survival benefits posed by the elimination of either host plasminogen or bacterial Pla. These studies, and complementary studies with other human pathogens, illustrate that plasminogen and fibrinogen are extremely effective modifiers of the inflammatory response in vivo and critical determinants of bacterial virulence and host defense. Detailed studies of the inflammatory response in mice with genetically-imposed modifications in coagulation and fibrinolytic factors underscore the regulatory crosstalk between the hemostatic and immune systems.

Interaction of fibrinogen with nanosilica

Interaction of human plasma fibrinogen (HPF) with fumed nanosilica A-300 in a phosphate buffer solution (PBS) was studied using 1H NMR spectroscopy with layer-by-layer freezing-out of bulk and interfacial water in the temperature range of 210–273 K, TSDC (90 T FTIR, and UV spectroscopy methods. An increase in concentration of HPF in the PBS leads to a decrease in amounts of structured water (frozen at T FTIR and UV spectra show that the HPF adsorption on silica leads to structural changes of the protein molecules. These changes and formation of hybrid HPF/A-300 aggregates can increase the rate of clotting that is of importance on nanosilica application as a component of tourniquet preparations.

TNF-alpha potentiates protein-tyrosine nitration through activation of NADPH oxidase and eNOS localized in membrane rafts and caveolae of bovine aortic endothelial cells

A major source of reactive oxygen species (ROS) in endothelial cells is the NADPH oxidase enzyme complex. The selective distributions of any enzyme within cells have important implications in regulating enzyme effectiveness through facilitation of access to local substrates and/or product targets. Because membrane rafts provide a spatially preferable environment for a variety of enzyme systems, we sought to determine whether NADPH oxidase is present and functional in this plasma membrane compartment in endothelial cells. We found that, in resting endothelial cells, NADPH oxidase subunits were preassembled and the enzyme functional in membrane rafts, specifically in caveolae. Stimulation with TNF-alpha induced additional recruitment of the p47(phox) regulatory subunit to raft-localized NADPH oxidase and enhanced ROS production within raft domains. TNF-alpha also induced nitric oxide production through activation of endothelial nitric oxide synthase (eNOS) present in the same membrane compartment. The dual activation of superoxide and nitric oxide-generating systems provided a spatially favorable environment for nitration of tyrosine-containing proteins localized to rafts. Perturbation of membrane raft structural integrity with cholesterol-sequestering compounds caused the delocalization of NADPH oxidase subunits and eNOS from the rafts and inhibited TNF-alpha-induced ROS production and protein tyrosine nitration. Together, these data provide evidence that membrane rafts and caveolae play a role in the spatial regulation of NADPH oxidase and subsequent ROS/reactive nitrogen species in endothelial cells.

The contribution of associated congenital anomalies in understanding Hirschsprung's disease

Hirschsprung's disease (HSCR) is a complex congenital disorder which, from a molecular perspective, appears to result due to disruption of normal signalling during development of enteric nerve cells, resulting in aganglionosis of the distal bowel. Associated congenital anomalies occur in at least 5-32% (mean 21%) of patients and certain syndromic phenotypes have been linked to distinct genetic sites, indicating underlying genetic associations of the disease and probable gene-gene interaction in its pathogenesis. Clear-cut associations with HSCR include Down's syndrome, dominant sensorineural deafness, Waardenburg syndrome, neurofibromatosis, neuroblastoma, phaeochromocytoma, the MEN type IIB syndrome and other abnormalities. Individual anomalies vary from 2.97% to 8%, the most frequent being the gastrointestinal tract (GIT) (8.05%), the central nervous system (CNS) and sensorineural anomalies (6.79%) and the genito-urinary tract (6.05%). Other associated systems include the musculoskeletal (5.12%), cardiovascular systems (4.99%), craniofacial and eye abnormalities (3%) and less frequently the skin and integumentary system (ectodermal dysplasia) and syndromes related to cholesterol and fat metabolism. In addition to associations with neuroblastoma and tumours related to MEN2B, HSCR may also be associated with tumours of neural origin such as ganglioneuroma, ganglioneuroblastoma, retinoblastoma and tumours associated with neurofibromatosis and other autonomic nervous system disturbances. The contribution of the major susceptibility genes on chromosome 10 (RET) and chromosome 13 (EDNRB) is well established in the phenotypic expression of HSCR. Whereas major RET mutations may result in HSCR by haploinsufficiency in 20-25% of cases, the etiology of the majority of sporadic HSCR is not as clear, appearing to arise from the combined cumulative effects of susceptibility loci at critical genes controlling the mechanisms of cell proliferation, differentiation and maturation. In addition, potential "modifying" associations exist with chromosome 2, 9, 20, 21 and 22, and we explore the importance of certain flanking genes of critical areas in the final phenotypic expression of HSCR.

Activation of Neutrophil Granulocytes in an In Vitro Model of a Cardiopulmonary Bypass

Activated neutrophils play a central role in the pathogenesis of postoperative organ dysfunction after surgery with cardiopulmonary bypass. The researchers used an in vitro roller pump model to investigate the relative importance of the biomaterial, platelets, plasma proteins including activated complement, and flow mode on neutrophil activation as shown by the adhesion, degranulation, and increased the surface expression of CD11b. Neutrophil adhesion to the biomaterial increased with platelet addition, but not with plasma. Biomaterial contact activated neutrophils in a serum-free buffer, but was significantly increased by activated complement. Platelets increased neutrophil degranulation in a serum-free buffer but tended to reduce it in plasma. CD11b expression increased in both media. Complement activation was higher with neutrophils alone than with neutrophils and platelets combined. The roller pump reduced neutrophil adhesion and increased degranulation compared to passive rotation. Neutrophil interaction with platelets and complement were more important for activation than biomaterial contact and use of the roller pump. Improvement of biocompatibility is dependent on modifying complement activation and platelet interaction with neutrophils.

Hypertonic saline enhances neutrophil elastase release through activation of P2 and A3 receptors

Hypertonic saline (HS) holds promise as a novel resuscitation fluid for the treatment of trauma patients because HS inhibits polymorphonuclear neutrophil (PMN) activation and thereby prevents host tissue damage and associated posttraumatic complications. However, depending on conditions of cell activation, HS can increase PMN degranulation, which could exacerbate tissue damage in trauma victims. The cellular mechanism by which HS increases degranulation is unknown. In the present study, we tested whether HS-induced ATP release from PMN and feedback via P1 and/or P2 receptors may be involved in the enhancement of degranulation by HS. We found that HS enhances elastase release and ERK and p38 MAPK activation when HS is added after activation of PMN with formyl peptide (fMLP) or phorbol ester (PMA). Agonists of P2 nucleotide and A3 adenosine receptors mimicked these enhancing effects of HS, whereas antagonists of A3 receptors or removal of extracellular ATP with apyrase diminished the response to HS. A1 adenosine receptor antagonists increased the enhancing effect of HS, whereas A1 receptor agonists inhibited elastase release. These data suggest that HS upregulates degranulation via ATP release and positive feedback through P2 and A3 receptors. We propose that these feedback mechanisms can serve as potential pharmacological targets to fine-tune the clinical effectiveness of HS resuscitation.

Chemical blockage of the proteasome inhibitory function of bortezomib: impact on tumor cell death

The proteasome inhibitor bortezomib is emerging as a potent anti-cancer agent. Still, recent clinical trials have revealed a significant secondary toxicity of bortezomib. Consequently, there is much interest in dissecting the mechanism of action of this compound to rationally improve its therapeutic index. The cytotoxic effect of bortezomib is frequently characterized by interfering with downstream events derived from the accumulation of proteasomal targets. Here we identify the first chemical agent able to act upstream of the proteasome to prevent cell killing by bortezomib. Specifically, we show that the polyhydroxyl compound Tiron can function as a competitive inhibitor of bortezomib. This effect of Tiron was surprising, since it is a classical radical spin trap and was expected to scavenge reactive oxygen species produced as a consequence of bortezomib action. The inhibitory effect of Tiron against bortezomib was selective, since it was not shared by other antioxidants, such as vitamin E, MnTBAP, L-N-acetyl-cysteine, and FK-506. Comparative analyses with nonboronated proteasome inhibitors (i.e. MG132) revealed a specificity of Tiron for bortezomib. We exploited this novel feature of Tiron to define the "point of no return" of proteasome inhibition in melanoma cells and to block cell death in a three-dimensional model of human skin. Cells from T-cell lymphoma, breast carcinoma, and non-small cell lung cancer were also responsive to Tiron, suggesting a broad impact of this agent as a bortezomib blocker. These results may have important implications for the analysis of bortezomib in vivo and for the design of drug mixtures containing proteasome inhibitors.

Involvement of SHIP in TLR2-induced neutrophil activation and acute lung injury

The SHIP converts phosphatidylinositol 3,4,5 triphosphate to phosphatidyl 3,4 biphosphate. SHIP has negative regulatory functions on PI3K-dependent signaling pathways, which occupy important roles in modulating neutrophil functions. We used neutrophils from transgenic SHIP(-/-) and SHIP(+/+) mice that were stimulated with peptidoglycan (PGN) to examine the role of SHIP in TLR2-induced neutrophil activation. SHIP(-/-) neutrophils demonstrated significantly increased activation of the PI3K-dependent kinase Akt after exposure to PGN. Release of cytokines and chemokines, including TNF-alpha, IL-1beta, IL-6, IL-10, and MIP-2, was also increased in SHIP(-/-) compared with SHIP(+/+) neutrophils. There was no difference in the nuclear translocation of the transcriptional factor NF-kappaB between PGN-stimulated SHIP(-/-) and SHIP(+/+) neutrophils. However, phosphorylation of the p65 subunit of NF-kappaB, an event essential for optimal transcriptional activity of NF-kappaB, was increased in TLR2-activated SHIP(-/-) neutrophils. SHIP(-/-) neutrophils demonstrated greater activation of ERK1/2 and p38 MAPKs than did SHIP(+/+) neutrophils after exposure to PGN. The severity of acute lung injury induced by PGN was greater in SHIP(-/-) as compared with SHIP(+/+) mice. These results demonstrate that SHIP has a negative regulatory role in TLR2-induced neutrophil activation and in the development of related in vivo neutrophil-dependent inflammatory processes, such as acute lung injury.

The role of the MAPK pathway alterations in GM-CSF modulated human neutrophil apoptosis with aging

Background

Neutrophils represent the first line of defence against aggressions. The programmed death of neutrophils is delayed by pro-inflammatory stimuli to ensure a proper resolution of the inflammation in time and place. The pro-inflammatory stimuli include granulocyte-macrophage colony-stimulating factor (GM-CSF). Recently, we have demonstrated that although neutrophils have an identical spontaneous apoptosis in elderly subjects compared to that in young subjects, the GM-CSF-induced delayed apoptosis is markedly diminished. The present study investigates whether an alteration of the GM-CSF stimulation of MAPKs play a role in the diminished rescue from apoptosis of PMN of elderly subjects.

Methods

Neutrophils were separated from healthy young and elderly donors satisfying the SENIEUR protocol. Neutrophils were stimulated with GM-CSF and inhibitors of the MAPKinase pathway. Apoptosis commitment, phosphorylation of signaling molecules, caspase-3 activities as well as expression of pro- and anti-apoptotic molecules were performed in this study. Data were analyzed using Student's two-tailed t-test for independent means. Significance was set for p ≤ 0.05 unless stated otherwise.

Results

In this paper we present evidence that an alteration in the p42/p44 MAPK activation occurs in PMN of elderly subjects under GM-CSF stimulation and this plays a role in the decreased delay of apoptosis of PMN in elderly. We also show that p38 MAPK does not play a role in GM-CSF delayed apoptosis in PMN of any age-groups, while it participates to the spontaneous apoptosis. Our results also show that the alteration of the p42/p44 MAPK activation contributes to the inability of GM-CSF to decrease the caspase-3 activation in PMN of elderly subjects. Moreover, GM-CSF converts the pro-apoptotic phenotype to an anti-apoptotic phenotype by modulating the bcl-2 family members Bax and Bcl-xL in PMN of young subjects, while this does not occur in PMN of elderly. However, this modulation seems MAPK independent.

Conclusion

Our results show that the alteration of p42/p44 MAPK activation contributes to the GM-CSF induced decreased PMN rescue from apoptosis in elderly subjects. The modulation of MAPK activation in PMN of elderly subjects might help to restore the functionality of PMN with aging.