Proteome of monocyte priming by lipopolysaccharide, including changes in interleukin-1beta and leukocyte elastase inhibitor

Factor XIII-A: An Indispensable "Factor" in Haemostasis and Wound Healing

Factor XIII (FXIII) is a transglutaminase enzyme that catalyses the formation of ε-(γ-glutamyl)lysyl isopeptide bonds into protein substrates. The plasma form, FXIIIA₂B₂, has an established function in haemostasis, with fibrin being its principal substrate. A deficiency in FXIII manifests as a severe bleeding diathesis emphasising its crucial role in this pathway. The FXIII-A gene (F13A1) is expressed in cells of bone marrow and mesenchymal lineage. The cellular form, a homodimer of the A subunits denoted FXIII-A, was perceived to remain intracellular, due to the lack of a classical signal peptide for its release. It is now apparent that FXIII-A can be externalised from cells, by an as yet unknown mechanism. Thus, three pools of FXIII-A exist within the circulation: plasma where it circulates in complex with the inhibitory FXIII-B subunits, and the cellular form encased within platelets and monocytes/macrophages. The abundance of this transglutaminase in different forms and locations in the vasculature reflect the complex and crucial roles of this enzyme in physiological processes. Herein, we examine the significance of these pools of FXIII-A in different settings and the evidence to date to support their function in haemostasis and wound healing.

Metformin partially reverses the inhibitory effect of co-culture with ER-/PR-/HER2+ breast cancer cells on biomarkers of monocyte antitumor activity

BACKGROUND

Immune activities of monocytes (MOs) can be altered within the microenvironment of solid malignancies, including breast cancer. Metformin (1,1-dimethylbiguanide hydrochloride, MET), has been shown to decrease tumor cell proliferation, but its effects have yet to be explored with respect to MOs (monocytes) activity during their crosstalk with breast cancer cells. Here, we investigated the effects of MET on overall phenotypic functional activities, including cellular immunometabolism and protective redox signaling based-biomarkers, intracellular free calcium ions (ifCa2+), phagocytosis and co-operative cytokines (IFN-γ and IL-10) of autologous MOs before and during their interplay with primary ER-/PR-/HER2+ breast cancer cells.

METHODS

Human primary breast cancer cells were either cultured alone or co-cultured with autologous MOs before treatment with MET.

RESULTS

MET downregulated breast cancer cell proliferation and phagocytosis, while having no significant effect on the ratio of phosphorylated Akt (p-Akt) to total Akt. Additionally, we observed that, in the absence of MET treatment, the levels of lactate dehydrogenase (LDH)-based cytotoxicity, catalase, ifCa2+, IL-10 and arginase activity were significantly reduced in co-cultures compared to levels in MOs cultured alone whereas levels of inducible nitric oxide synthase (iNOS) activity were significantly increased. In contrast, MET treatment reduced the effects measured in co-culture on the levels of LDH-based cytotoxicity, arginase activity, catalase, ifCa2+, and IFN-γ. MET also induced upregulation of both iNOS and arginase in MO cells, although the increase did not reach significant difference for iNOS activity. Moreover, MET induced a robust increase of superoxide dismutase (SOD) activity in MOs, but not in MOs co-cultured with breast cancer cells. Furthermore, MET markedly upregulated the levels of IFN-γ production and downregulated those of IL-10 in isolated MOs, while inducing a slight opposing up-regulation of IL-10 production in co-cultures.

CONCLUSIONS

Our results show that the biomarkers of phenotypic functional activities of MOs are modified after co-culturing with primary human breast cancer cells. Treatment of co-cultures with MET resulted in increased release of antitumor cytokine IFN-γ and ifCa2+, and increased cell necrosis during breast cancer cells-MOs crosstalk.

Anti-inflammatory activity of superoxide dismutase mimics functionalized with cell-penetrating peptides

A superoxide dismutase mimic was functionalized with three peptides: -R9, -RRWWRRWRR or -F_x-r-F_x-K (MPP). They were studied in intestinal epithelial cells in an inorganic cellular chemistry approach: quantification, distribution and bio-activity.

Characterization of a novel protein identified by proteomics analysis as a modulator of inflammatory networks in amphioxus

Inflammatory response is an innate host defense mechanism, and its regulation is essential for the host to get rid of harm by the excessive reactions. We first utilized proteomics approach to identify amphioxus humoral fluid proteins in response to LPS-induced inflammation. A total of 26 differentially expressed proteins, mainly involved in energy metabolism and cytoskeleton rearrangement processes, were identified between LPS-treated and control animals. Furthermore, we found a single uncharacterized protein (termed BjIM1) out of the most up-regulated ones, and examined its role in the regulation of immune and inflammatory responses. BjIM1 is predominantly expressed in the hepatic caecum, and its promoter sequence includes many binding sites for immune-relevant transcription factors. Importantly, recombinant BjIM1 (rBjIM1) is able to inhibit LPS-induced up-regulation of TLR pathway genes, such as MyD88, IKK, NF-κB1, Rel, p38, JNK and AP-1, indicating that BjIM1 may negatively regulate the TLR signaling pathway in amphioxus. Moreover, rBjIM1 also modulates the expression of genes involved in the interaction network of inflammation, energy metabolism and cytoskeleton rearrangement, including SIRT1, Rac1 and NOX2, in the LPS-induced inflammatory response in amphioxus. Collectively, our studies suggest that BjIM1 is an uncharacterized protein functioning as a modulator of inflammatory networks in amphioxus.

Let's cross-link: diverse functions of the promiscuous cellular transglutaminase factor XIII-A

Essentials Plasma Factor XIII, a heterodimer of A and B subunits FXIIIA2 B2 , is a transglutaminase enzyme with a well-established role in haemostasis. Cells of bone marrow and mesenchymal lineage express the FXIII-A gene (F13A1) that encodes the cellular form of the transglutaminase, a homodimer of the A subunits, FXIII-A. FXIII-A was presumed to function intracellularly, however, several lines of evidence now indicate that FXIII-A is externalised by an as yet unknown mechanism This review describes the mounting evidence that FXIII-A is a diverse transglutaminase with many intracellular and extracellular substrates that can participate in an array of biological processes SUMMARY: Factor XIII is a tranglutaminase enzyme that catalyzes the formation of ε-(γ-glutamyl)lysyl isopeptide bonds in protein substrates. The plasma form, FXIII-A2 B2 , has an established function in hemostasis, where its primary substrate is fibrin. A deficiency in FXIII manifests as a severe bleeding diathesis, underscoring its importance in this pathway. The cellular form of the enzyme, a homodimer of the A-subunits, denoted FXIII-A, has not been studied in as extensive detail. FXIII-A was generally perceived to remain intracellular, owing to the lack of a classical signal peptide for its release. In the last decade, emerging evidence has revealed that this diverse transglutaminase can be externalized from cells, by an as yet unknown mechanism, and can cross-link extracellular substrates and participate in a number of diverse pathways. The FXIII-A gene (F13A1) is expressed in cells of bone marrow and mesenchymal lineage, notably megakaryocytes, monocytes/macrophages, dendritic cells, chrondrocytes, osteoblasts, and preadipocytes. The biological processes that FXIII-A is coupled with, such as wound healing, phagocytosis, and bone and matrix remodeling, reflect its expression in these cell types. This review describes the mounting evidence that this cellular transglutaminase can be externalized, usually in response to stimuli, and participate in extracellular cross-linking reactions. A corollary of being involved in these biological pathways is the participation of FXIII-A in pathological processes. In conclusion, the functions of this transglutaminase extend far beyond its role in hemostasis, and our understanding of this enzyme in terms of its secretion, regulation and substrates is in its infancy.

Sepsis Through the Eyes of Proteomics: The Progress in the Last Decade

Sepsis is a systemic inflammatory response caused by infection whose molecular mechanisms are still not completely understood. The early detection of sepsis remains a great challenge for clinicians because no single biomarker capable of its reliable prediction, hence, delayed diagnosis frequently undermines treatment efforts, thereby contributing to high mortality. There are several experimental approaches used to reveal the molecular mechanism of sepsis progression. Proteomics coupled with mass spectrometry made possible to identify differentially expressed proteins in clinical samples. Recent advancement in liquid chromatography-based separation methods and mass spectrometers resolution and sensitivity with absolute quantitation methods, made possible to use proteomics as a powerful tool for study of clinical samples with higher coverage proteome profiles. In recent years, number of proteomic studies have been done under sepsis and/or in response to endotoxin and showed various signaling pathways, functions, and biomarkers. This review enlightened the proteomic progress in the last decade in sepsis.

In-Depth Proteomic Characterization of Classical and Non-Classical Monocyte Subsets

Monocytes are bone marrow-derived leukocytes that are part of the innate immune system. Monocytes are divided into three subsets: classical, intermediate and non-classical, which can be differentiated by their expression of some surface antigens, mainly CD14 and CD16. These cells are key players in the inflammation process underlying the mechanism of many diseases. Thus, the molecular characterization of these cells may provide very useful information for understanding their biology in health and disease. We performed a multicentric proteomic study with pure classical and non-classical populations derived from 12 healthy donors. The robust workflow used provided reproducible results among the five participating laboratories. Over 5000 proteins were identified, and about half of them were quantified using a spectral counting approach. The results represent the protein abundance catalogue of pure classical and enriched non-classical blood peripheral monocytes, and could serve as a reference dataset of the healthy population. The functional analysis of the differences between cell subsets supports the consensus roles assigned to human monocytes.

Phage on Tap: A Quick and Efficient Protocol for the Preparation of Bacteriophage Laboratory Stocks

A major limitation with traditional phage preparations is the variability in titer, salts, and bacterial contaminants between successive propagations. Here, we introduce the Phage On Tap (PoT) protocol for the quick and efficient preparation of homogenous bacteriophage (phage) stocks. This method produces homogenous, laboratory-scale, high titer (up to 10^10-12 PFU/mL), endotoxin reduced phage banks that can be used to eliminate the variability between phage propagations, improve the molecular characterizations of phage, and may be applicable for therapeutic applications. The method consists of five major parts, including phage propagation, phage cleanup by 0.22 μm filtering and chloroform treatment, phage concentration by ultrafiltration, endotoxin removal, and the preparation and storage of phage banks for continuous laboratory use. From a starting liquid lysate of >100 mL, the PoT protocol generated a cleaned, homogenous, laboratory phage bank with a phage recovery efficiency of 85% within just 2 days. In contrast, the traditional method took upward of 5 days to produce a high titer, but lower volume phage stock with a recovery efficiency of only 4%. Phage banks can be further purified for the removal of bacterial endotoxins, reducing endotoxin concentrations by over 3000-fold while maintaining phage titer. The PoT protocol focused on T-like phages, but is broadly applicable to a variety of phages that can be propagated to sufficient titer, producing homogenous, high titer phage banks that are applicable for molecular and cellular assays.

Molecular Regulation of Sprouting Angiogenesis

The term angiogenesis arose in the 18th century. Several studies over the next 100 years laid the groundwork for initial studies performed by the Folkman laboratory, which were at first met with some opposition. Once overcome, the angiogenesis field has flourished due to studies on tumor angiogenesis and various developmental models that can be genetically manipulated, including mice and zebrafish. In addition, new discoveries have been aided by the ability to isolate primary endothelial cells, which has allowed dissection of various steps within angiogenesis. This review will summarize the molecular events that control angiogenesis downstream of biochemical factors such as growth factors, cytokines, chemokines, hypoxia-inducible factors (HIFs), and lipids. These and other stimuli have been linked to regulation of junctional molecules and cell surface receptors. In addition, the contribution of cytoskeletal elements and regulatory proteins has revealed an intricate role for mobilization of actin, microtubules, and intermediate filaments in response to cues that activate the endothelium. Activating stimuli also affect various focal adhesion proteins, scaffold proteins, intracellular kinases, and second messengers. Finally, metalloproteinases, which facilitate matrix degradation and the formation of new blood vessels, are discussed, along with our knowledge of crosstalk between the various subclasses of these molecules throughout the text. Compr Physiol 8:153-235, 2018.

Unbiased Quantitative Proteomics Reveals a Crucial Role of the Allergen Context for the Activation of Human Dendritic Cells

Worldwide, more than 1 billion people suffer from allergic diseases. However, until now it is not fully understood how certain proteins can induce allergic immune responses, while others cannot. Studies suggest that allergenicity is a process not only determined by properties of the allergen itself but also by costimulatory factors, that are not classically associated with allergic reactions. To investigate the allergenicity of the major birch pollen allergen Bet v 1 and the impact of adjuvants associated with pollen, e.g. lipopolysaccharide (LPS), we performed quantitative proteome analysis to study the activation of monocyte-derived dendritic cells (moDCs). Thus, we treated cells with birch pollen extract (BPE), recombinant Bet v 1, and LPS followed by proteomic profiling via high-performance liquid chromatography and tandem mass spectrometry (HPLC-MS/MS) using isobaric labelling. Enrichment and pathway analysis revealed the influence of regulated proteins especially in cytokine signalling and dendritic cell activation. We found highly regulated, but differentially expressed proteins after treatment with BPE and LPS, whereas the cellular response to Bet v 1 was limited. Our findings lead to the conclusion that Bet v 1 needs a specific “allergen context” involving cofactors apart from LPS to induce an immune response in human moDCs.

Retinal pigment epithelium and microglia express the CD5 antigen-like protein, a novel autoantigen in age-related macular degeneration

We report on a novel autoantigen expressed in human macular tissues, identified following an initial Western blot (WB)-based screening of sera from subjects with age-related macular degeneration (AMD) for circulating auto-antibodies (AAbs) recognizing macular antigens. Immunoprecipitation, 2D-gel electrophoresis (2D-GE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), direct enzyme-linked immunosorbent assays (ELISA), WBs, immunohistochemistry (IHC), human primary and ARPE-19 immortalized cell cultures were used to characterize this novel antigen. An approximately 40-kDa autoantigen in AMD was identified as the scavenger receptor CD5 antigen-like protein (CD5L), also known as apoptosis inhibitor of macrophage (AIM). CD5L/AIM was localized to human RPE by IHC and WB methods and to retinal microglial cells by IHC. ELISAs with recombinant CD5L/AIM on a subset of AMD sera showed a nearly 2-fold higher anti-CD5L/AIM reactivity in AMD vs. Control sera (p = 0.000007). Reactivity ≥0.4 was associated with 18-fold higher odds of having AMD (χ² = 21.42, p = 0.00063). Circulating CD5L/AIM levels were also nearly 2-fold higher in AMD sera compared to controls (p = 0.0052). The discovery of CD5L/AIM expression in the RPE and in retinal microglial cells adds to the known immunomodulatory roles of these cells in the retina. The discovery of AAbs recognizing CD5L/AIM identifies a possible novel disease biomarker and suggest a potential role for CD5L/AIM in the pathogenesis of AMD in situ. The possible mechanisms via which anti-CD5L/AIM AAbs may contribute to AMD pathogenesis are discussed. In particular, since CD5L is known to stimulate autophagy and to participate in oxidized LDL uptake in macrophages, we propose that anti-CD5L/AIM auto-antibodies may play a role in drusen biogenesis and inflammatory RPE damage in AMD.

Phage on tap-a quick and efficient protocol for the preparation of bacteriophage laboratory stocks

A major limitation with traditional phage preparations is the variability in titer, salts, and bacterial contaminants between successive propagations. Here we introduce the Phage On Tap (PoT) protocol for the quick and efficient preparation of homogenous bacteriophage (phage) stocks. This method produces homogenous, laboratory-scale, high titer (up to 10^10–11 PFU·ml⁻¹), endotoxin reduced phage banks that can be used to eliminate the variability between phage propagations and improve the molecular characterizations of phage. The method consists of five major parts, including phage propagation, phage clean up by 0.22 μm filtering and chloroform treatment, phage concentration by ultrafiltration, endotoxin removal, and the preparation and storage of phage banks for continuous laboratory use. From a starting liquid lysate of > 100 mL, the PoT protocol generated a clean, homogenous, laboratory phage bank with a phage recovery efficiency of 85% within just two days. In contrast, the traditional method took upwards of five days to produce a high titer, but lower volume phage stock with a recovery efficiency of only 4%. Phage banks can be further purified for the removal of bacterial endotoxins, reducing endotoxin concentrations by over 3,000-fold while maintaining phage titer. The PoT protocol focused on T-like phages, but is broadly applicable to a variety of phages that can be propagated to sufficient titer, producing homogenous, high titer phage banks that are applicable for molecular and cellular assays.

Circulating Autoantibodies in Age-Related Macular Degeneration Recognize Human Macular Tissue Antigens Implicated in Autophagy, Immunomodulation, and Protection from Oxidative Stress and Apoptosis

BACKGROUND

We investigated sera from elderly subjects with and without age-related macular degeneration (AMD) for presence of autoantibodies (AAbs) against human macular antigens and characterized their identity.

METHODS

Sera were collected from participants in the Age-Related Maculopathy Ancillary (ARMA) Study, a cross-sectional investigation ancillary to the Health ABC Study, enriched with participants from the general population. The resulting sample (mean age: 79.2±3.9 years old) included subjects with early to advanced AMD (n = 131) and controls (n = 231). Sera were tested by Western blots for immunoreactive bands against human donor macular tissue homogenates. Immunoreactive bands were identified and graded, and odds ratios (OR) calculated. Based on these findings, sera were immunoprecipitated, and subjected to 2D gel electrophoresis (GE). Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to identify the targets recognized by circulating AAbs seen on 2D-GE, followed by ELISAs with recombinant proteins to confirm LC-MS/MS results, and quantify autoreactivities.

RESULTS

In AMD, 11 immunoreactive bands were significantly more frequent and 13 were significantly stronger than in controls. Nine of the more frequent bands also showed stronger reactivity. OR estimates ranged between 4.06 and 1.93, and all clearly excluded the null value. Following immunoprecipitation, 2D-GE and LC-MS/MS, five of the possible autoreactivity targets were conclusively identified: two members of the heat shock protein 70 (HSP70) family, HSPA8 and HSPA9; another member of the HSP family, HSPB4, also known as alpha-crystallin A chain (CRYAA); Annexin A5 (ANXA5); and Protein S100-A9, also known as calgranulin B that, when complexed with S100A8, forms calprotectin. ELISA testing with recombinant proteins confirmed, on average, significantly higher reactivities against all targets in AMD samples compared to controls.

CONCLUSIONS

Consistent with other evidence supporting the role of inflammation and the immune system in AMD pathogenesis, AAbs were identified in AMD sera, including early-stage disease. Identified targets may be mechanistically linked to AMD pathogenesis because the identified proteins are implicated in autophagy, immunomodulation, and protection from oxidative stress and apoptosis. In particular, a role in autophagy activation is shared by all five autoantigens, raising the possibility that the detected AAbs may play a role in AMD via autophagy compromise and downstream activation of the inflammasome. Thus, we propose that the detected AAbs provide further insight into AMD pathogenesis and have the potential to contribute to disease biogenesis and progression.

Proteomics Reveals a Role for Attachment in Monocyte Differentiation into Efficient Proinflammatory Macrophages

Monocytes are blood-borne cells of the innate immune system. They can be differentiated and activated into proinflammatory macrophages that might be employed in tumor immune therapy. Monocyte exposure to lipopolysaccharide (LPS) is a standard method to induce a proinflammatory macrophage state, with the resultant population comprising both adherent and nonadherent cells. In the current study, we aimed to identify the differences in proteomes of these monocyte subpopulations, which addresses a more general question about the role of attachment in monocyte differentiation. Label-free proteomics of a model of human monocytes (THP-1 cell line) revealed that the cells remaining in suspension upon LPS treatment were activated by cytokines and primed for rapid responsiveness to pathogens. In terms of proteome change, the adhesion process was orthogonal to activation. Adherent cells exhibited signs of differentiation and enhanced innate immune responsivity, being closer to macrophages. These findings indicate that adherent, LPS-treated cells would be more appropriate for use in tumor therapeutic applications.

The comparative proteomics analysis revealed the modulation of inducible nitric oxide on the immune response of scallop Chlamys farreri

Nitric oxide (NO) is an important gasotransmitter which plays a key role on the modulation of immune response in all vertebrates and invertebrates. In the present study, the modulation of inducible NO on immune response of scallop Chlamys farreri was investigated via proteomic analysis. Total proteins from hepatopancreas of scallops treated with lipopolysaccharide (LPS) and/or the inhibitor of vertebrate inducible NO synthase (S-methylisothiourea sulfate, SMT) for 12 h were analyzed via 2-D PAGE and ImageMaster 2D Platinum. There were 890, 1189 and 1046 protein spots detected in the groups treated by phosphate buffered saline (PBS), LPS and LPS+SMT, respectively, and 26 differentially expressed protein spots were identified among them. These proteins were annotated with binding or catalytic activity, and most of them were involved in metabolic or cellular processes. Some immune-related or antioxidant-related molecules such as single Ig IL-1-related receptor, guanine nucleotide-binding protein subunit beta-like protein and peroxiredoxin were identified, and the changes of their expression levels in LPS group were intensified significantly after adding SMT. The decreased expression level of tyrosinase and increased level of glutathione S-transferase 4 in LPS group were diametrically reversed by appending SMT. Moreover, interferon stimulated exonuclease gene 20-like protein and copper chaperone for superoxide dismutase were only induced by LPS+SMT stimulation but not by LPS stimulation. These data indicated that NO could modulate many immunity processes in scallop, such as NF-κB transactivation, cytoskeleton reorganization and other pivotal processes, and it was also involved in the energy metabolism, posttranslational modification, detoxification and redox balance during the immune response.

The role of proteomics in understanding biological mechanisms of sepsis

Sepsis is a systemic inflammatory state caused by infection. Complications of this infection with multiple organ failure lead to more lethal conditions, such as severe sepsis and septic shock. Sepsis is one of the leading causes of US deaths. Novel biomarkers with high sensitivity and specificity may be helpful for early diagnosis of sepsis and for improvement of patient outcomes through the development of new therapies. Mass spectrometry-based proteomics offers powerful tools to identify such biomarkers and furthermore to give insight to fundamental mechanisms of this clinical condition. In this review, we summarize findings from proteomics studies of sepsis and how their applications have provided more understanding into the pathogenesis of septic infection. Literatures related to "proteomics", "sepsis", "systemic inflammatory response syndrome", "severe sepsis", "septic infection", and "multiple organ dysfunction syndrome" were searched using PubMed. Findings about neonatal and adult sepsis are discussed separately. Within the adult sepsis studies, results are grouped based on the models (e.g., human or animal). Across investigations in clinical populations and in rodent and mammalian animal models, biological pathways, such as inflammatory and acute phase response, coagulation, complement, mitochondrial energy metabolism, chaperones, and oxidative stress, are altered at the protein level. These proteomics studies have discovered many novel biomarker candidates of septic infection. Validation the clinical use of these biomarker candidates may significantly impact the diagnosis and prognosis of sepsis. In addition, the molecular mechanisms revealed by these studies may also guide the development of more effective treatments.

Application of SILAC labeling to primary bone marrow-derived dendritic cells reveals extensive GM-CSF-dependent arginine metabolism

Although dendritic cells (DCs) control the priming of the adaptive immunity response, a comprehensive description of their behavior at the protein level is missing. The introduction of the quantitative proteomic technique of metabolic labeling (SILAC) into the field of DC research would therefore be highly beneficial. To achieve this, we applied SILAC labeling to primary bone marow-derived DCs (BMDCs). These cells combine both biological relevance and experimental feasibility, as their in vitro generation permits the use of (13)C/(15)N-labeled amino acids. Interestingly, BMDCs appear to exhibit a very active arginine metabolism. Using standard cultivation conditions, ∼20% of all protein-incorporated proline was a byproduct of heavy arginine degradation. In addition, the dissipation of (15)N from labeled arginine to the whole proteome was observed. The latter decreased the mass accuracy in MS and affected the natural isotopic distribution of peptides. SILAC-connected metabolic issues were shown to be enhanced by GM-CSF, which is used for the differentiation of DC progenitors. Modifications of the cultivation procedure suppressed the arginine-related effects, yielding cells with a proteome labeling efficiency of ≥90%. Importantly, BMDCs generated according to the new cultivation protocol preserved their resemblance to inflammatory DCs in vivo, as evidenced by their response to LPS treatment.

Proteomic and systems biology analysis of monocytes exposed to securinine, a GABA(A) receptor antagonist and immune adjuvant

Securinine, a GABA(A) receptor antagonist, has been reported to enhance monocyte cell killing of Coxiella burnetii without obvious adverse effects in vivo. We employed multiplex 2D gel electrophoresis using Zdyes, a new generation of covalently linked fluorescent differential protein detection dyes to analyze changes in the monocyte proteome in response to Securinine. Securinine antagonism of GABA(A) receptors triggers the activation of p38. We used the differential protein expression results to guide a search of the literature and network analysis software to construct a systems biology model of the effect of Securinine on monocytes. The model suggests that various metabolic modulators (fatty acid binding protein 5, inosine 5'-monophosphate dehydrogenase, and thioredoxin) are at least partially reshaping the metabolic landscape within the monocytes. The actin bundling protein L-plastin, and the Ca(2+) binding protein S100A4 also appear to have important roles in the immune response stimulated by Securinine. Fatty acid binding protein 5 (FABP5) may be involved in effecting lipid raft composition, inflammation, and hormonal regulation of monocytes, and the model suggests that FABP5 may be a central regulator of metabolism in activated monocytes. The model also suggests that the heat shock proteins have a significant impact on the monocyte immune response. The model provides a framework to guide future investigations into the mechanisms of Securinine action and with elaboration may help guide development of new types of immune adjuvants.

Factor XIII: a coagulation factor with multiple plasmatic and cellular functions

Factor XIII (FXIII) is unique among clotting factors for a number of reasons: 1) it is a protransglutaminase, which becomes activated in the last stage of coagulation; 2) it works on an insoluble substrate; 3) its potentially active subunit is also present in the cytoplasm of platelets, monocytes, monocyte-derived macrophages, dendritic cells, chondrocytes, osteoblasts, and osteocytes; and 4) in addition to its contribution to hemostasis, it has multiple extra- and intracellular functions. This review gives a general overview on the structure and activation of FXIII as well as on the biochemical function and downregulation of activated FXIII with emphasis on new developments in the last decade. New aspects of the traditional functions of FXIII, stabilization of fibrin clot, and protection of fibrin against fibrinolysis are summarized. The role of FXIII in maintaining pregnancy, its contribution to the wound healing process, and its proangiogenic function are reviewed in details. Special attention is given to new, less explored, but promising fields of FXIII research that include inhibition of vascular permeability, cardioprotection, and its role in cartilage and bone development. FXIII is also considered as an intracellular enzyme; a separate section is devoted to its intracellular activation, intracellular action, and involvement in platelet, monocyte/macrophage, and dendritic cell functions.

The augmented neutrophil respiratory burst in response to Escherichia coli is reduced in liver cirrhosis during infection

Several functional abnormalities in phagocytes from patients with liver cirrhosis contribute to an increased risk of infection. An increased resting respiratory burst has been observed in neutrophils from cirrhotic patients. We investigated whether an infection in cirrhosis affects the respiratory burst capacity of neutrophils and monocytes in response to Escherichia coli. This study included 45 hospitalized patients with liver cirrhosis and clinical signs of infection, 39 patients with liver cirrhosis in the absence of infection and 29 healthy subjects. Respiratory burst, lipopolysaccharide-binding protein (LBP), and immunoglobulin (Ig)G-autoantibodies against oxidized low-density lipoproteins (ab-oxLDL) were measured. The fraction of neutrophils spontaneously producing reactive oxygen species (ROS) was elevated in liver cirrhosis (P < 0·01). The neutrophil resting burst increased with Child-Pugh stage (P = 0·02) and correlated with augmented ROS release in response to opsonized E. coli (P < 0·05). Although LBP was increased in patients with cirrhosis (P < 0·01), higher LBP levels correlated with a lower resting burst in neutrophils (r(s)  = -0·395; P < 0·01). In the presence of infection, the resting burst was unaltered. However, neutrophil ROS release in response to E. coli was reduced markedly (P = 0·01), and it decreased as serum C-reactive protein (CRP) concentration rose (r(s)  = -0·437; P < 0·01), indicating the development of a sepsis-like immune paralysis. A positive correlation between ab-oxLDL and ROS release was observed (P < 0·01). In conclusion, the respiratory burst increases with severity of liver cirrhosis but is restrained by increasing LBP levels. Augmented ROS release in response to E. coli is accompanied by elevated markers of oxidative damage and becomes exhausted in the presence of infection.

Study of monocyte membrane proteome perturbation during lipopolysaccharide-induced tolerance using iTRAQ-based quantitative proteomic approach

Human monocytes' exposure to low-level lipopolysaccharide (LPS) induces temporary monocytic insensitivity to subsequent LPS challenge. The underlying mechanism of this phenomenon could have important clinical utilities in preventing and/or treating severe infections. In this study, we used an iTRAQ-based quantitative proteomic approach to comprehensively characterize the membrane proteomes of monocytes before and after LPS exposure. We identified a total of 1651 proteins, of which 53.6% were membrane proteins. Ninety-four percent of the proteins were quantified and 255 proteins were shown to be tightly regulated by LPS. Subcellular location analysis revealed organelle-specific response to LPS exposure: more than 90% of identified mitochondrial membrane proteins were significant downregulated, whereas the majority of proteins from other organelles such as ER, Golgi and ribosome were upregulated. Moreover, we found that the expression of most receptors potentially involved in LPS signal pathway (CD14, toll-like receptor 4, CD11/CD18 complex) were substantially decreased, while the expression of molecules involved in LPS neutralization were enhanced after LPS challenge. Together, these findings could be of significance in understanding the mechanism of LPS tolerance and provide values for designing new approaches for regulating monocytic responses in sepsis patients.

Exogenous mammalian extracellular HSP70 reduces endotoxin manifestations at the cellular and organism levels

In this study, we checked whether HSP70 preparations of different origins are able to protect model animals (rats) from endotoxic shock and modify the response of myeloid cells to lipopolysaccharide (LPS) challenge. It was shown that HSP70 preparations can effectively protect organisms from endotoxic shock by strongly decreasing mortality and restoring both homeostasis and various hemodynamic characteristics. At the cellular level, HSP70 preparations significantly inhibit LPS-induced reactive oxygen species production in various myeloid cells and decrease NO expression in macrophages, which is enhanced after LPS priming. In parallel, HSP70 preconditioning partially normalizes neutrophil apoptosis, which is disturbed as a result of LPS stimulation. These results suggest that the antiseptic actions of HSP70 preparations are probably realized at the level of receptor membrane complexes of myeloid cells, which represent the major target of LPS action. Taken together, our findings show that extracellular mammalian HSP70 may play an important role in innate immunity modulation and stimulation of endogenous protective mechanisms, both at the cellular and organism levels, which make this protein a promising base for the development of efficient antiseptic drugs.

Applications of proteomics in the study of inflammatory bowel diseases: Current status and future directions with available technologies

Inflammatory bowel diseases (IBD) are chronic, heterogeneous, and multifactorial intestinal inflammatory disorders. Major challenges in IBD research include identification of major pathogenic alterations of genes/proteins as well as effective biomarkers for early diagnosis, prognosis, and prediction of therapeutic response. Since proteins govern cellular structure and biological function, a wide selection of proteomic approaches enables effective characterization of IBD pathogenesis by investigating the dynamic nature of protein expression, cellular and subcellular distribution, posttranslational modifications, and interactions at both the cellular and subcellular levels. The aims of this review are to 1) highlight the current status of proteomic studies of IBD, and 2) introduce the available and emerging proteomic technologies that have potential applications in the study of IBD. These technologies include various mass spectrometry technologies, quantitative proteomics (2D-PAGE, ICAT, SILAC, iTRAQ), protein/antibody arrays, and multi-epitope-ligand cartography. This review also presents information and methodologies, from sample selection and enrichment to protein identification, that are not only essential but also particularly relevant to IBD research. The potential future application of these technologies is expected to have a significant impact on the discovery of novel biomarkers and key pathogenic factors for IBD.