Bactericidal/permeability-increasing Protein Research Articles

Low-grade systemic inflammation in patients with long COVID: The role of imbalance of endotoxin-releasing systems and vasoconstrictor markers

Background. Currently, the pathophysiological mechanisms of acute damage to organs and systems caused by coronavirus infection have been studied quite fully, but the mechanisms underlying the clinical manifestations of long COVID have not yet been accurately described. The mechanisms of persistence of a number of symptoms in patients who have had COVID-19 and the role of systemic inflammation and endotoxemia markers in it remain a understudied aspect and a promising direction for further studying.The aim of the study. To assess the markers of systemic inflammation, endotoxin-releasing systems, intestinal permeability and endothelial dysfunction in patients with long COVID at the stage of health resort treatment.Methods. The study included 32 patients who had recovered from coronavirus infection and were undergoing health resort treatment in the pulmonology department of the I.M. Sechenov Academic Research Institute for Physical Therapy, Medical Climatology and Rehabilitation. We also selected a control group (n = 20). All patients underwent peripheral blood analysis to detect the levels of markers of systemic inflammation, endotoxin-releasing systems, intestinal permeability, endothelial dysfunction and vasoconstrictor agents: C-reactive protein (CRP), lipopolysaccharide-binding protein (LPB), tissue-type plasminogen activator (tPA), zonulin, bactericidal/ permeability-increasing protein (BPI), vasopressors of angiotensin 2 and endothelin (EDN1).Results. Patients who had recovered from coronavirus infection had a statistically significant increase in the levels of CRP (3.4 [2.56; 4.0] mg/l), LBP (18.46 [14.0; 25.5] ng/ml), tPA (0.07 [0.02; 0.32] ng/ml), angiotensin 2 (133.3 [63.0; 503.7] pg/ml) and a decrease in the level of BPI (1576 [276; 3588] pg/ml) (p < 0.05).Conclusion. A statistically significant increase in markers of systemic inflammation, endotoxinemia, and vasoconstrictor agents in patients with long COVID indicates an imbalance in endotoxin-binding and endotoxin-releasing systems in patients who have had coronavirus infection. Further study of the described markers is necessary to improve approaches to long-term personalized therapy for this category of patients.

Plasma levels of bactericidal/permeability-increasing protein correlate with systemic inflammation in acute coronary syndrome

BackgroundNeutrophils play important roles in atherosclerosis and atherothrombosis. Bactericidal/permeability-increasing protein (BPI) is mainly expressed in the granules of human neutrophils in response to inflammatory stress. This observational, cross-sectional study investigated the plasma level of BPI in patients with acute coronary syndrome (ACS) and its correlation with blood neutrophil counts and circulating inflammatory biomarkers. MethodsA total of 367 patients who had acute chest pain and who were admitted to our hospital for coronary angiography (CAG) and/or percutaneous coronary intervention (PCI) from May 1, 2020 to August 31, 2020 were recruited. Among them, 256 had a cardiac troponin value above the 99th percentile upper reference limit and were diagnosed with ACS. The remaining patients (n = 111) were classified as non-ACS. The TIMI and GRACE scores were calculated at admission. The Gensini score based on CAG was used to determine atherosclerotic burden. Plasma levels of interleukin (IL)-1β, myeloperoxidase-DNA (MPO-DNA), high sensitivity C-reactive protein (hs-CRP), S100A8/A9, and BPI were measured using enzyme-linked immunosorbent assays. Correlations of plasma BPI levels with examination scores and levels of circulating inflammatory biomarkers were explored. Receiver operating characteristic (ROC) curve analysis was used to determine the diagnostic efficacy of BPI for ACS and myocardial infarction. ResultsPatients in the ACS group showed significantly higher plasma BPI levels compared to the non-ACS group (46.42 ± 16.61 vs. 16.23 ± 6.19 ng/mL, p < 0.05). Plasma levels of IL-1β, MPO-DNA, hs-CRP, and S100A8/A9 in the ACS group were also significantly higher than those in the non-ACS group (all p < 0.05). In addition, plasma BPI levels were positively correlated with the TIMI, GRACE, and Gensini scores (r = 0.176, p = 0.003; r = 0.320, p < 0.001; r = 0.263, p < 0.001, respectively) in patients with ACS. Plasma BPI levels were also positively correlated with blood neutrophil counts (r = 0.266, p < 0.001) and levels of circulating inflammatory biomarkers (IL-1β, r = 0.512; MPO-DNA, r = 0.452; hs-CRP, r = 0.554; S100A8/A9, r = 0.434; all p < 0.001) in patients with ACS. ROC curve analysis revealed that the diagnostic efficacy of BPI for ACS was not inferior to that of IL-1β, MPO-DNA, hs-CRP, S100A8/A9, or blood neutrophil counts. ROC analysis also showed that the diagnostic efficacy of BPI for myocardial infarction was not inferior to that of creatine kinase (CK)-MB or cardiac troponin I. ConclusionBPI is associated with systemic inflammation in ACS and may be involved in the process of atherosclerosis and atherothrombosis. The potential of BPI as a prognostic and diagnostic biomarker for ACS should be investigated in clinical settings.

Bactericidal Permeability-Increasing Protein (BPI) Inhibits Mycobacterium tuberculosis Growth.

Bactericidal permeability-increasing protein (BPI) is a multifunctional cationic protein produced by neutrophils, eosinophils, fibroblasts, and macrophages with antibacterial anti-inflammatory properties. In the context of Gram-negative infection, BPI kills bacteria, neutralizes the endotoxic activity of lipopolysaccharides (LPSs), and, thus, avoids immune hyperactivation. Interestingly, BPI increases in patients with Gram-positive meningitis, interacts with lipopeptides and lipoteichoic acids of Gram-positive bacteria, and significantly enhances the immune response in peripheral blood mononuclear cells. We evaluated the antimycobacterial and immunoregulatory properties of BPI in human macrophages infected with Mycobacterium tuberculosis. Our results showed that recombinant BPI entered macrophages, significantly reduced the intracellular growth of M. tuberculosis, and inhibited the production of the proinflammatory cytokine tumor necrosis factor-alpha (TNF-α). Furthermore, BPI decreased bacterial growth directly in vitro. These data suggest that BPI has direct and indirect bactericidal effects inhibiting bacterial growth and potentiating the immune response in human macrophages and support that this new protein's broad-spectrum antibacterial activity has the potential for fighting tuberculosis.

Serum proteomic profiling of patients with compensated advanced chronic liver disease with and without clinically significant portal hypertension.

Portal hypertension (PH) drives the progression of liver cirrhosis to decompensation and death. Hepatic venous pressure gradient (HVPG) measurement is the standard of PH quantification, and HVPG≥10 mmHg defines clinically significant PH (CSPH). We performed proteomics-based serum profiling to search for a proteomic signature of CSPH in patients with compensated advanced chronic liver disease (cACLD). Consecutive patients with histologically confirmed cACLD and results of HVPG measurements were prospectively included. Serum samples were pooled according to the presence/absence of CSPH and analysed by liquid chromatography-mass spectrometry. Gene set enrichment analysis was performed, followed by comprehensive literature review for proteins identified with the most striking difference between the groups. We included 48 patients (30 with, and 18 without CSPH). Protein CD44, involved in the inflammatory response, vascular endothelial growth factor C (VEGF-C) and lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1), both involved in lymphangiogenesis were found solely in the CSPH group. Although identified in both groups, proteins involved in neutrophil extracellular traps (NET) formation, as well as tenascin C, autotaxin and nephronectin which mediate vascular contractility and lymphangiogenesis were more abundant in CSPH. We propose that altered inflammatory response, including NET formation, vascular contractility and formation of new lymph vessels are key steps in PH development. Proteins such as CD44, VEGF-C, LYVE-1, tenascin C, Plasminogen activator inhibitor 1, Nephronectin, Bactericidal permeability-increasing protein, Autotaxin, Myeloperoxidase and a disintegrin and metalloproteinase with thrombospondin motifs-like protein 4 might be considered for further validation as potential therapeutic targets and candidate biomarkers of CSPH in cACLD.

Subversion of a family of antimicrobial proteins by Salmonella enterica.

Salmonella enterica is a food-borne pathogen able to cause a wide spectrum of diseases ranging from mild gastroenteritis to systemic infections. During almost all stages of the infection process Salmonella is likely to be exposed to a wide variety of host-derived antimicrobial peptides (AMPs). AMPs are important components of the innate immune response which integrate within the bacterial membrane, thus forming pores which lead ultimately to bacterial killing. In contrast to other AMPs Bactericidal/Permeability-increasing Protein (BPI) displayed only weak bacteriostatic or bactericidal effects towards Salmonella enterica sv. Typhimurium (STM) cultures. Surprisingly, we found that sub-antimicrobial concentrations of BPI fold-containing (BPIF) superfamily members mediated adhesion of STM depending on pre-formed type 1 fimbriae. BPIF proteins directly bind to type 1 fimbriae through mannose-containing oligosaccharide modifications. Fimbriae decorated with BPIF proteins exhibit extended binding specificity, allowing for bacterial adhesion on a greater variety of abiotic and biotic surfaces likely promoting host colonization. Further, fimbriae significantly contributed to the resistance against BPI, probably through sequestration of the AMP before membrane interaction. In conclusion, functional subversion of innate immune proteins of the BPIF family through binding to fimbriae promotes Salmonella virulence by survival of host defense and promotion of host colonization.

Genes and Pathways Underpinning Klinefelter Syndrome at Bulk and Single-Cell Levels.

Klinefelter syndrome (KS) is the most frequent genetic anomaly in infertile men. Given its unclear mechanism, we aim to investigate critical genes and pathways in the pathogenesis of KS based on three bulk and one single-cell transcriptome data sets from Gene Expression Omnibus. We merged two data sets (GSE42331 and GSE47584) with human KS whole blood samples. When comparing the control and KS samples, five hub genes, including defensin alpha 4 (DEFA4), bactericidal permeability increasing protein (BPI), myeloperoxidase (MPO), intelectin 1 (ITLN1), and Xg Glycoprotein (XG), were identified. Besides, infiltrated degree of certain immune cells such as CD56bright NK cell were positively associated with the expression of ITLN1 and XG. Kyoto Encyclopedia of Genes and Genomes analysis identified upregulated phosphatidylinositol 3-kinase (PI3K)/AKT pathway in KS. Gene set enrichment analysis followed by gene set variation analysis confirmed the upregulation of G2M checkpoint and heme metabolism in KS. Thereafter, the GSE200680 data set was used for external validation of the expression variation of hub genes from healthy to KS testicular samples, and each hub gene yielded excellent discriminatory capability for KS without exception. At the single-cell level, the GSE136353 data set was utilized to evaluate intercellular communication between different cell types in KS patient, and strong correlations were detected between macrophages/ dendritic cells/ NK cells and the other cell types. Collectively, we provided hub genes, pathways, immune cell infiltration degree, and cell-cell communication in KS, warranting novel insights into the pathogenesis of this disease.

Acute and chronic rhinosinusitis age characteristics

Children's and adults' rhinosinusitis are two diseases that have both similarities and differences in anatomy, epidemiology, causes, pathogenesis, diagnosis and treatment. At the same rhinosinusitis is one of the most common in otorhinolaryngology's practice, both in children and adults. The of adults paranasal sinuses (PNS) anatomy differs from children's PNS anatomy. Although ostiomeatal complex occlusion is recognized as a major cause of poor ventilation and drainage of the adult paranasal sinuses, it does not have a strong effect on pediatric rhinosinusitis, but adenoids play a key role. Adenoids are bacteria and biofilms reservoirs that cause chronic refractory rhinosinusitis regardless of pharyngeal tonsil size. The prevalence of chronic rhinosinusitis (CRS) is lower in children than in adults. Diagnosis of children's rhinosinusitis is more difficult because nasal cavity endoscopic examination is performed rarely due to the occasional need of general anesthesia during the procedure. Moreover, it's necessary to take into account prevailing etiological role of viruses in ARS at children's age and chronic adenoiditis often accompanies pediatric CRS, which requires attention prescribing medical therapy as the basis of rhinosinusitis treatment. The DysheLORz based on Pelargonium sidoides roots is highly effective and safe for children's and adults ARS and CRS treatment, both as monotherapy and in combination with topical steroids and antibiotics. This herbal medicine immunomodulatory effect is mediated mainly by stimulating the production of TNF-α, IL-1, IL-12 and IFN-γ. It activates macrophages and improves their phagocytic activity. IL-12, together with TNF-α, enhances NK and cytotoxic CD8+ lymphocytes' activity against infected cells. IL-12 effect on Th1 lymphocytes maturation provides a link between innate and adaptive immunity. This is also increasing MCP-1, IP-10 and MIP-1β chemokines synthesis and decreasing MIP-1α, ENA-78, GROα and IL-8 production in PNS and nasal mucosa. This leads to decrease of neutrophils chemotaxis to the inflammation site, and decline of serine proteases concentration (neutrophils main enzymes), that increases mucous membrane epithelial barrier permeability, reducing bacterial infections risk. Additionally, Pelargonium sidoides increases epithelial cells beating cilia frequency and inhibits hemagglutinin and neuraminidase present on influenza virus surface. The drug increases antimicrobial peptides production as defensins, human neutrophil peptides (HNP) and bactericidal permeability-increasing protein (BPI), which is also important for rapid inflammation regression in rhinosinusitis. It causes bacterial adhesion to epithelial cells inhibition, phagocytosis stimulation, nitric oxide (NO) release and oxidative burst. The medicine had a direct effect on Streptococcus pneumoniae, Staphylococcus aureus, Neisseria, Moraxella catarrhalis and Haemophilus influenza. Based on these data, it is possible to explain the high effectiveness and safety of the drugs based on Pelargonium sidoides in ENT organs inflammation treatment, for both adults and children over 1 year old.

BPI23-Fcγ alleviates lethal multi-drug-resistant Acinetobacter baumannii infection by enhancing bactericidal activity and orchestrating neutrophil function

Antibiotic resistance has become a major threat, contributing significantly to morbidity and mortality globally. Administering non-antibiotic therapy, such as antimicrobial peptides, is one potential strategy for effective treatment of multi-drug-resistant Gram-negative bacterial infections. Bactericidal/permeability-increasing protein (BPI) derived from neutrophils has bactericidal and endotoxin-neutralizing activity. However, the protective roles and mechanisms of BPI in multi-drug-resistant bacterial infections have not been fully elucidated. In this study, a chimeric BPI23-Fcγ recombined protein comprising the functional N terminus of BPI and Fcγ was constructed and expressed by adenovirus vector 5 (Ad5). Ad5-BPI23-Fcγ or recombinant BPI23-Fcγ protein significantly improved the survival of mice with pneumonia induced by a minimal lethal dose of multi-drug-resistant Acinetobacter baumannii or Klebsiella pneumoniae by ameliorating lung pathology and reducing pro-inflammatory cytokines. Transfection with Ad5-BPI23-Fcγ significantly decreased the bacterial load and endotoxaemia,which was associated with enhanced bactericidal ability and elevated the phagocytic activity of neutrophils in vitro and in vivo. In addition, Ad5-BPI23-Fcγ transfection significantly increased the recruitment of neutrophils to lung, increased the proportion and number of neutrophils in peripheral blood, and promoted the maturation of bone marrow (BM) neutrophils after drug-resistant A. baumannii infection. BPI23-Fcγ and neutrophils synergistically enhanced bactericidal activity and decreased pro-inflammatory cytokines. These results demonstrated that the chimeric BPI23-Fcγ protein protected mice from pneumonia induced by multi-drug-resistant A. baumannii infection by direct bactericidal effects and promotion of neutrophil recruitment, phagocytosis and maturation. Chimeric BPI23-Fcγ may be a promising candidate as a non-antibiotic biological agent for multi-drug-resistant A. baumannii infection.

Scorpionfish BPI is highly active against multiple drug-resistant Pseudomonas aeruginosa isolates from people with cystic fibrosis.

Chronic pulmonary infection is a hallmark of cystic fibrosis (CF) and requires continuous antibiotic treatment. In this context, Pseudomonas aeruginosa (Pa) is of special concern since colonizing strains frequently acquire multiple drug resistance (MDR). Bactericidal/permeability-increasing protein (BPI) is a neutrophil-derived, endogenous protein with high bactericidal potency against Gram-negative bacteria. However, a significant range of people with CF (PwCF) produce anti-neutrophil cytoplasmic antibodies against BPI (BPI-ANCA), thereby neutralizing its bactericidal function. In accordance with literature, we describe that 51.0% of a total of 39 PwCF expressed BPI-ANCA. Importantly, an orthologous protein to human BPI (huBPI) derived from the scorpionfish Sebastes schlegelii (scoBPI) completely escaped recognition by these autoantibodies. Moreover, scoBPI exhibited high anti-inflammatory potency towards Pa LPS and was bactericidal against MDR Pa derived from PwCF at nanomolar concentrations. In conclusion, our results highlight the potential of highly active orthologous proteins of huBPI in treatment of MDR Pa infections, especially in the presence of BPI-ANCA.

Comparative transcriptome analysis reveals immunoregulation mechanism in the spleen of large yellow croaker (Larimichthys crocea) in response to Vibrio harveyi infection

Large yellow croaker (Larimichthys crocea) is a commercially important fish species worldwide, but high-density cultivation has led to serious diseases especially by Vibrio harveyi. Understanding the molecular response of large yellow croaker to V. harveyi infection is vital for the development of effective measures to combat the disease. In this study, RNA-Seq was performed on the spleen of uninfected and V. harveyi-infected large yellow croaker. A total of 7527 differentially expressed genes (DEGs) were identified, with 4413 up-regulated and 3114 down-regulated genes. Functional enrichment analysis revealed that several immune-related pathways were highlighted, including Toll-like receptors (TLRs) signaling pathway, apoptosis, p53 signaling pathway, and lysosome. In the TLRs signaling pathway, up-regulated genes included IL1b, bactericidal permeability-increasing protein, and IL12b, while down-expressed genes included tlr3 and irf3. The apoptosis pathway showed up-regulated genes such as casp6, bcl-2-like protein, and cytochrome c, and down-expressed genes such as granzyme B, sptan1, and FADD-Fas (tnfrsf6)-associated via death domain. These results suggest that V. harveyi infection induced inflammatory response and apoptotic cell death in the spleen of large yellow croaker. This study provides valuable insights into the molecular mechanisms underlying the immune response of large yellow croaker to V. harveyi infection

Identification and Functional Analysis of ToBPI1/LBP and ToBPI2/LBP in Anti-Bacterial Infection of Trachinotus ovatus.

Bactericidal/permeability-increasing protein (BPI) and lipopolysaccharide-binding protein (LBP) are a group of antibacterial proteins that play an important role in the host's innate immune defense against pathogen infection. In this study, two BPI/LBPs, named ToBPI1/LBP (1434 bp in length, 478 amino acids) and ToBPI2/LBP (1422 bp in length, 474 amino acids), were identified from the golden pompano. ToBPI1/LBP and ToBPI2/LBP were significantly expressed in immune-related tissues after being challenged with Streptococcus agalactiae and Vibrio alginolyticus. The two BPI/LBPs showed significant antibacterial activity against Gram-negative Escherichia coli and Gram-positive S. agalactiae and Streptococcus iniae. In contrast, the antibacterial activity against Staphylococcus aureus, Corynebacterium glutamicum, Vibrio parahaemolyticus, V. alginolyticus and Vibrio harveyi was low and decreased with time. The membrane permeability of bacteria treated with recombinant ToBPI1/LBP and ToBPI2/LBP was significantly enhanced. These results suggest that ToBPI1/LBP and ToBPI2/LBP may play important immunological roles in the immune response of the golden pompano to bacteria. This study will provide basic information and new insights into the immune response mechanism of the golden pompano to bacteria and the function of BPI/LBP.

Lipocalin-2 and neutrophil activation in pancreatic cancer cachexia.

Cancer cachexia is a multifactorial syndrome characterized by body weight loss and systemic inflammation. The characterization of the inflammatory response in patients with cachexia is still limited. Lipocalin-2, a protein abundant in neutrophils, has recently been implicated in appetite suppression in preclinical models of pancreatic cancer cachexia. We hypothesized that lipocalin-2 levels could be associated with neutrophil activation and nutritional status of pancreatic ductal adenocarcinoma (PDAC) patients. Plasma levels of neutrophil activation markers calprotectin, myeloperoxidase, elastase, and bactericidal/permeability-increasing protein (BPI) were compared between non-cachectic PDAC patients (n=13) and cachectic PDAC patients with high (≥26.9 ng/mL, n=34) or low (<26.9 ng/mL, n=34) circulating lipocalin-2 levels. Patients' nutritional status was assessed by the patient-generated subjective global assessment (PG-SGA) and through body composition analysis using CT-scan slices at the L3 level. Circulating lipocalin-2 levels did not differ between cachectic and non-cachectic PDAC patients (median 26.7 (IQR 19.7-34.8) vs. 24.8 (16.6-29.4) ng/mL, p=0.141). Cachectic patients with high systemic lipocalin-2 levels had higher concentrations of calprotectin, myeloperoxidase, and elastase than non-cachectic patients or cachectic patients with low lipocalin-2 levels (calprotectin: 542.3 (355.8-724.9) vs. 457.5 (213.3-606.9), p=0.448 vs. 366.5 (294.5-478.5) ng/mL, p=0.009; myeloperoxidase: 30.3 (22.1-37.9) vs. 16.3 (12.0-27.5), p=0.021 vs. 20.2 (15.0-29.2) ng/mL, p=0.011; elastase: 137.1 (90.8-253.2) vs. 97.2 (28.8-215.7), p=0.410 vs. 95.0 (72.2-113.6) ng/mL, p=0.006; respectively). The CRP/albumin ratio was also higher in cachectic patients with high lipocalin-2 levels (2.3 (1.3-6.0) as compared to non-cachectic patients (1.0 (0.7-4.2), p=0.041). Lipocalin-2 concentrations correlated with those of calprotectin (rs =0.36, p<0.001), myeloperoxidase (rs =0.48, p<0.001), elastase (rs =0.50, p<0.001), and BPI (rs =0.22, p=0.048). Whereas no significant correlations with weight loss, BMI, or L3 skeletal muscle index were observed, lipocalin-2 concentrations were associated with subcutaneous adipose tissue index (rs =-0.25, p=0.034). Moreover, lipocalin-2 tended to be elevated in severely malnourished patients compared with well-nourished patients (27.2 (20.3-37.2) vs. 19.9 (13.4-26.4) ng/mL, p=0.058). These data suggest that lipocalin-2 levels are associated with neutrophil activation in patients with pancreatic cancer cachexia and that it may contribute to their poor nutritional status.

Salmonella Typhimurium PgtE is an essential arsenal to defend against the host resident antimicrobial peptides

Salmonella enterica serovar Typhimurium is a common cause of gastroenteritis in humans and occasionally causes systemic infection. Salmonella's ability to survive and replicate within macrophages is an important characteristic during systemic infection. The outer membrane protease PgtE of S. enterica is a member of the Omptin family of outer membrane aspartate proteases which has well-characterized proteolytic activities in-vitro against a wide range of physiologically relevant substrates. However, no study has been done so far that draws a direct correlation between these in-vitro observations and the biology of the pathogen in-vivo. The main goals of this study were to characterize the pathogenesis-associated functions of pgtE and study its role in the intracellular survival and in-vivo virulence of Salmonella Typhimurium. Our study elucidated a possible role of Salmonella Typhimurium pgtE in combating host antimicrobial peptide- bactericidal/ permeability increasing protein (BPI) to survive in human macrophages. The pgtE-deficient strain of Salmonella showed attenuated proliferation and enhanced colocalization with BPI in U937 and Thp1 cells. In the presence of polymixin B, the attenuated in-vitro survival of STM ΔpgtE suggested a role of PgtE against the antimicrobial peptides. In addition, our study revealed that compared to the wild type Salmonella, the pgtE mutant is replication-deficient in C57BL/6 mice. Further, we showed that PgtE interacts directly with several antimicrobial peptides (AMPs) in the host gut. This gives the pathogen a survival advantage and helps to mount a successful infection in the host

Resistance of Argopecten purpuratus scallop larvae to vibriosis is associated with the front-loading of immune genes and enhanced antimicrobial response.

Mass mortality events caused by vibriosis have emerged in hatchery-reared scallop larvae from Chile, threatening scallop aquaculture. In an attempt to mitigate this emerging infectious disease and provide candidates for marker-assisted selective breeding, we tested here the existence of a genetic component of Argopecten purpuratus scallop resistance to the pathogen Vibrio bivalvicida. Through a dual RNA-seq approach we analyzed the basal transcriptome and the transcriptional response to infection in two resistant and two susceptible families as well as the pathogen transcriptomic response to host colonization. The results highlighted a genetic basis in the resistance of scallop larvae to the pathogen. The Vibrio response was characterized by a general metabolic adaptation to the host environment, along with several predicted virulence factors overexpressed in infected scallop larvae with no difference between resistant and susceptible host phenotypes. On the host side, several biological processes were enriched in uninfected resistant larvae. Within these enriched categories, immune-related processes were overexpressed, while morphogenesis, biomineral tissue development, and angiogenesis were under expressed. Particularly, genes involved in immune recognition and antimicrobial response, such as lipopolysaccharide-binding proteins (LBPs), lysozyme, and bactericidal permeability-increasing protein (BPI) were overexpressed in uninfected resistant larvae. As expected, immune-related biological processes were enriched in Vibrio-infected larvae, but they were more numerous in resistant larvae. Overexpressed immune genes in response to infection included several Toll-like receptors, TNF and NF-κB immune signaling genes, and the antimicrobial peptide Big defensin ApBD1. Results strongly suggest that both a front-loading of immune genes and an enhanced antimicrobial response to infection contribute to the resistance, while pathogen infective strategy does not discriminate between host phenotypes. Overall, early expression of host immune genes appears as a strong determinant of the disease outcome that could be used in marker-assisted selective breeding.

LL-37 Triggers Antimicrobial Activity in Human Platelets.

Platelets play a crucial role in hemostasis and the immune response, mainly by recognizing signals associated with vascular damage. However, it has recently been discovered that the antimicrobial peptide LL-37 activates platelets in functions related to thrombus formation and inflammation. Therefore, this work aims to evaluate the effect of LL-37 on the activation of antimicrobial functions of human platelets. Our results show that platelets treated with LL-37 increase the surface expression of receptors (Toll-like receptors (TLRs) 2 and -4, CD32, CD206, Dectin-1, CD35, LOX-1, CD41, CD62P, and αIIbβ3 integrins) for the recognition of microorganisms, and molecules related to antigen presentation to T lymphocytes (CD80, CD86, and HLA-ABC) secrete the antimicrobial molecules: bactericidal/permeability-increasing protein (BPI), azurocidin, human neutrophil peptide (HNP) -1, and myeloperoxidase. They also translate azurocidin, and have enhanced binding to Escherichia coli, Staphylococcus aureus, and Candida albicans. Furthermore, the supernatant of LL-37-treated platelets can inhibit E. coli growth, or platelets can employ their LL-37 to inhibit microbial growth. In conclusion, these findings demonstrate that LL-37 participates in the antimicrobial function of human platelets.

Characterising the autoantibody repertoire in systemic sclerosis following myeloablative haematopoietic stem cell transplantation

ObjectivesResults from the SCOT (Scleroderma: Cyclophosphamide Or Transplantation) clinical trial demonstrated significant benefits of haematopoietic stem cell transplant (HSCT) versus cyclophosphamide (CTX) in patients with systemic sclerosis. The objective of...

Bactericidal permeability-increasing protein/LPS-binding protein (BPI/LBP) enhances resistance of golden pompano Trachinotus ovatus against bacterial infection

Antimicrobial peptides are crucial components of innate immunity against microbial invasions. As a kind of antimicrobial peptides, bactericidal permeability-increasing protein (BPI)/lipopolysaccharide-binding protein (LBP) play vital roles in defending the host against gram-negative bacteria. In the current study, a novel BPI/LBP from Trachinotus ovatus (TroBPI/LBP) was characterized. The full length of TroBPI/LBP cDNA sequence is 1434 bp, which contained 477 amino acids. Multiple amino acid alignments of TroBPI/LBP shows 34.07%–84.49% identity with other fish BPI/LBP. Similar to other BPI/LBP, TroBPI/LBP also possesses an N-terminal signal peptide, a BPI/LBP/CETP N-terminal domain, and a BPI/LBP/CETP C-terminal domain. In vitro, the recombinant protein of TroBPI/LBP showed effective bacterial depression activity and binding activity to gram-negative bacteria. In vivo, TroBPI/LBP was constitutively expressed in tested tissues, and the highest expression level was in liver. Following Vibrio alginolyticus stimulation, the mRNA expression of TroBPI/LBP was significantly upregulated in immune-related tissues, and peaked at 12 h post-infection, which confirmed that TroBPI/LBP was highly sensitive to V. alginolyticus stimuli. Furthermore, functional analyses showed that the overexpression of TroBPI/LBP could enhance the ability of fish to against V. alginolyticus infection, and the knockdown of TroBPI/LBP significantly diminished bacterial clearance capacity post-infection. Therefore, these results suggest that TroBPI/LBP may play an important role in host defense against bacterial infection.

Bactericidal/Permeability-Increasing Protein Downregulates the Inflammatory Response in In Vivo Models of Arthritis.

We investigated the effects of bactericidal/permeability-increasing protein (BPI) alone or in combination with hyaluronic acid (HA) in two animal models: collagen-induced arthritis (CIA) and crystal-induced inflammation. In CIA, mice were intraperitoneally injected with PBS, HA, or BPI plus or minus HA, twice a week for 2 months, and then euthanized to collect paw and blood. Arthritis was assessed in ankle joints by clinical and histological evaluation. Pathogenic crystals were intraperitoneally injected in mice plus or minus BPI, or with a composition of BPI and HA. After sacrifice, total and differential leukocyte counts were determined. Cytokine levels were measured in serum and peritoneal fluids. In CIA mice, BPI improved clinical and histological outcomes (histological scores ≥2-fold), and downregulated inflammatory mediators (47-93%). In crystal-induced inflammation, BPI reduced leukocyte infiltration (total count: ≥60%; polymorphonuclear cells: ≥36%) and inhibited cytokine production (35-74%). In both models, when mice were co-treated with BPI and HA, the improvement of all parameters was greater than that observed after administration of the two substances alone. Results show that BPI attenuates CIA and inflammation in mice, and this effect is enhanced by HA co-administration. Combined use of BPI and HA represents an interesting perspective for new potential treatments in arthritis.

Identification and functional characterization of bactericidal permeability/increasing protein (BPI) from frog Nanorana yunnanensis (Paa yunnanensis)

Bactericidal permeability/increasing protein (BPI) and lipopolysaccharide-binding protein (LBP) have been most extensively studied in mammals, but little information is available regarding BPI and LBP in Amphibia. In this study we showed that the cDNA of BPI in the frog N. yunnanensis (P. yunnanensis) encoded a 490-amino-acid-long protein, the predicted tertiary structure appears closely similar to mammalian BPIs in terms of sequence and structure. Like mammalian BPI gene, the frog gene nybpi was widely expressed in various tissues and was inducible by challenge with LPS or Gram-negative bacterium. We also showed that recombinant NyBPI, resembling mammalian BPIs, specifically binds with LPS. In addition, the recombinant NyBPI displayed antibacterial activity against Gram-negative bacteria Vibrio anguillarum in a dose-dependent manner. These results indicate that NyBPI may play an important role in an immune response against bacteria in amphibians.

Distinct Uptake Routes Participate in Silver Nanoparticle Engulfment by Earthworm and Human Immune Cells.

The consequences of engineered silver nanoparticle (AgNP) exposure and cellular interaction with the immune system are poorly understood. The immunocytes of the Eisenia andrei earthworm are frequently applied in ecotoxicological studies and possess functional similarity to vertebrate macrophages. Hence, we characterized and compared the endocytosis mechanisms for the uptake of 75 nm AgNPs by earthworm coelomocytes, human THP-1 monocytes, and differentiated THP-1 (macrophage-like) cells. Our results indicate that microtubule-dependent, scavenger–receptor, and PI3K signaling-mediated macropinocytosis are utilized during AgNP engulfment by human THP-1 and differentiated THP-1 cells. However, earthworm coelomocytes employ actin-dependent phagocytosis during AgNPs uptake. In both human and earthworm immunocytes, AgNPs were located in the cytoplasm, within the endo-/lysosomes. We detected that the internalization of AgNPs is TLR/MyD88-dependent, also involving the bactericidal/permeability-increasing protein (BPI) in the case of human immunocytes. The exposure led to decreased mitochondrial respiration in human immunocytes; however, in coelomocytes, it enhanced respiratory parameters. Our findings provide more data about NP trafficking as nano-carriers in the nanomedicine field, as well as contribute to an understanding of the ecotoxicological consequences of nanoparticle exposure.