Cellular responses to FMLP challenging: a mini-review

Programmable stopped-flow injection analysis: A comparative study on the effects of adenosine and its aptamer on respiratory burst of salivary and circulatory neutrophils

Neutrophils play a pivotal role in innate immunity by releasing ROS through respiratory bursts to neutralize various pathogenic factors. However, excessive ROS release can cause tissue damage. Adenosine is an endogenous anti-inflammatory molecule inhibiting respiratory burst to protect the host. Adenosine aptamers with antibody-like properties and good stability are expected to act as adenosine antagonists with functional modulation capability. This study compares the effects of adenosine and its aptamer on the respiratory bursts of salivary polymorphonuclear leukocytes and circulating polymorphonuclear leukocytes using a programmable stopped-flow injection approach, ensuring rapid and efficient analysis while maintaining the neutrophils' viability. The results show that primed salivary polymorphonuclear leukocytes exhibit specificities that differ from circulating polymorphonuclear leukocytes. Adenosine aptamer can function as an inhibitory antagonist that distinguishes between physiologically controlled and excessive priming of neutrophils, showing potential application prospects in immunotherapy.

The Effect of Local Anesthetics on Neutrophils in the Context of Different Isolation Techniques

Various functions of polymorphonuclear neutrophils (PMNs) are related to diseases and postoperative plasma changes. The influence of some local anesthetics (LAs) on PMNs obtained by conventional isolation methods and their functions has already been demonstrated. This study investigates the effect of selected LAs on PMNs, comparing a new isolation method with conventional ones. To obtain the PMNs, we performed either gelafundin sedimentation, hypotonic lysis or density gradient centrifugation. Subsequently, PMNs were mixed with different concentrations of bupivacaine, levobupivacaine, lidocaine or ropivacaine. Live cell imaging and flow cytometry were performed to quantify the migration, ROS production, NETosis and antigen expression of PMNs. We found the inhibition of chemotaxis and ROS production by LAs. PMNs showed a strong reduction in time to half maximal NETosis in response to bupivacaine and lidocaine, but not to levobupivacaine and ropivacaine. We also found distinct differences in survival time and migration duration between the isolation methods. This suggests that the careful selection of LAs has a short-term impact on in vitro PMNs.

From Bench to Bedside: What Do We Know about Imidazothiazole Derivatives So Far?

Imidazothiazole derivatives are becoming increasingly important in therapeutic use due to their outstanding physiological activities. Recently, applying imidazothiazole as the core, researchers have synthesized a series of derivatives with biological effects such as antitumor, anti-infection, anti-inflammatory and antioxidant effects. In this review, we summarize the main pharmacological effects and pharmacological mechanisms of imidazothiazole derivates; the contents summarized herein are intended to advance the research and rational development of imidazothiazole-based drugs in the future.

Sweetener System Intervention Shifted Neutrophils from Homeostasis to Priming

BACKGROUND

Non-nutritive sweeteners (NNS) are part of personalized nutrition strategies supporting healthy glycemic control. In contrast, the consumption of non-nutritive sweeteners has been related to person-specific and microbiome-dependent glycemic impairments. Reports on the effects of NNS on our highly individual cellular immune system are sparse. The recent identification of taste receptor expression in a variety of immune cells, however, suggested their immune-modulatory relevance.

METHODS

We studied the influence of a beverage-typical NNS system on the transcriptional profiling of sweetener-cognate taste receptors, selected cytokines and their receptors, and on Ca²⁺ signaling in isolated blood neutrophils. We determined plasma concentrations of saccharin, acesulfame-K, and cyclamate by HPLC-MS/MS, upon ingestion of a soft drink-typical sweetener surrogate. In an open-labeled, randomized intervention study, we determined pre- versus post-intervention transcript levels by RT-qPCR of sweetener-cognate taste receptors and immune factors.

RESULTS

Here we show that the consumption of a food-typical sweetener system modulated the gene expression of cognate taste receptors and induced the transcriptional regulation signatures of early homeostasis- and late receptor/signaling- and inflammation-related genes in blood neutrophils, shifting their transcriptional profile from homeostasis to priming. Notably, sweeteners at postprandial plasma concentrations facilitated fMLF (N-formyl-Met-Leu-Phe)-induced Ca²⁺ signaling.

CONCLUSIONS

Our results support the notion of sweeteners priming neutrophils to higher alertness towards their adequate stimuli.

Gene expression changes implicate specific peripheral immune responses to Deep and Lobar Intracerebral Hemorrhages in humans

The peripheral immune system response to Intracerebral Hemorrhage (ICH) may differ with ICH in different brain locations. Thus, we investigated peripheral blood mRNA expression of Deep ICH, Lobar ICH, and vascular risk factor-matched control subjects (n = 59). Deep ICH subjects usually had hypertension. Some Lobar ICH subjects had cerebral amyloid angiopathy (CAA). Genes and gene networks in Deep ICH and Lobar ICH were compared to controls. We found 774 differentially expressed genes (DEGs) and 2 co-expressed gene modules associated with Deep ICH, and 441 DEGs and 5 modules associated with Lobar ICH. Pathway enrichment showed some common immune/inflammatory responses between locations including Autophagy, T Cell Receptor, Inflammasome, and Neuroinflammation Signaling. Th2, Interferon, GP6, and BEX2 Signaling were unique to Deep ICH. Necroptosis Signaling, Protein Ubiquitination, Amyloid Processing, and various RNA Processing terms were unique to Lobar ICH. Finding amyloid processing pathways in blood of Lobar ICH patients suggests peripheral immune cells may participate in processes leading to perivascular/vascular amyloid in CAA vessels and/or are involved in its removal. This study identifies distinct peripheral blood transcriptome architectures in Deep and Lobar ICH, emphasizes the need for considering location in ICH studies/clinical trials, and presents potential location-specific treatment targets.

Molecular recognition of formylpeptides and diverse agonists by the formylpeptide receptors FPR1 and FPR2

The formylpeptide receptors (FPRs) mediate pattern recognition of formylated peptides derived from invading pathogens or mitochondria from dead host cells. They can also sense other structurally distinct native peptides and even lipid mediators to either promote or resolve inflammation. Pharmacological targeting of FPRs represents a novel therapeutic approach in treating inflammatory diseases. However, the molecular mechanisms underlying FPR ligand recognition are elusive. We report cryo-EM structures of G_i-coupled FPR1 and FPR2 bound to a formylpeptide and G_i-coupled FPR2 bound to two synthetic peptide and small-molecule agonists. Together with mutagenesis data, our structures reveal the molecular mechanism of formylpeptide recognition by FPRs and structural variations of FPR1 and FPR2 leading to their different ligand preferences. Structural analysis also suggests that diverse FPR agonists sample a conserved activation chamber at the bottom of ligand-binding pockets to activate FPRs. Our results provide a basis for rational drug design on FPRs.

Therapeutic evaluation of immunomodulators in reducing surgical wound infection

Despite many advances in infection control practices, including prophylactic antibiotics, surgical site infections (SSIs) remain a significant cause of morbidity, prolonged hospitalization, and death worldwide. Our innate immune system possesses a multitude of powerful antimicrobial strategies which make it highly effective in combating bacterial, fungal, and viral infections. However, pathogens use various stealth mechanisms to avoid the innate immune system, which in turn buy them time to colonize wounds and damage tissues at surgical sites. We hypothesized that immunomodulators that can jumpstart and activate innate immune responses at surgical sites, would likely reduce infection at surgical sites. We used three immunomodulators; fMLP (formyl-Methionine-Lysine-Proline), CCL3 (MIP-1α), and LPS (Lipopolysaccharide), based on their documented ability to elicit strong inflammatory responses; in a surgical wound infection model with Pseudomonas aeruginosa to evaluate our hypothesis. Our data indicate that one-time topical treatment with these immunomodulators at low doses significantly increased proinflammatory responses in infected and uninfected surgical wounds and were as effective, (or even better), than a potent prophylactic antibiotic (Tobramycin) in reducing P. aeruginosa infection in wounds. Our data further show that immunomodulators did not have adverse effects on tissue repair and wound healing processes. Rather, they enhanced healing in both infected and uninfected wounds. Collectively, our data demonstrate that harnessing the power of the innate immune system by immunomodulators can significantly boost infection control and potentially stimulate healing. We propose that topical treatment with these immunomodulators at the time of surgery may have therapeutic potential in combating SSI, alone or in combination with prophylactic antibiotics.

Rapid pathogen-specific recruitment of immune effector cells in the skin by secreted toxins

Swift recruitment of phagocytic leucocytes is critical in preventing infection when bacteria breach through the protective layers of the skin. According to canonical models, this occurs via an indirect process that is initiated by contact of bacteria with resident skin cells and which is independent of the pathogenic potential of the invader. Here we describe a more rapid mechanism of leucocyte recruitment to the site of intrusion of the important skin pathogen Staphylococcus aureus that is based on direct recognition of specific bacterial toxins, the phenol-soluble modulins (PSMs), by circulating leucocytes. We used a combination of intravital imaging, ear infection and skin abscess models, and in vitro gene expression studies to demonstrate that this early recruitment was dependent on the transcription factor EGR1 and contributed to the prevention of infection. Our findings refine the classical notion of the non-specific and resident cell-dependent character of the innate immune response to bacterial infection by demonstrating a pathogen-specific high-alert mechanism involving direct recruitment of immune effector cells by secreted bacterial products.

Age Associated Microbiome and Microbial Metabolites Modulation and Its Association With Systemic Inflammation in a Rhesus Macaque Model

Aging is associated with declining immunity and inflammation as well as alterations in the gut microbiome with a decrease of beneficial microbes and increase in pathogenic ones. The aim of this study was to investigate the age associated gut microbiome in relation to immunologic and metabolic profile in a non-human primate (NHP) model. 12 geriatric (age 19-24 years) and 4 young adult (age 3-4 years) Rhesus macaques were included in this study. Immune cell subsets were characterized in peripheral blood mononuclear cells (PBMC) by flow cytometry and plasma cytokines levels were determined by bead based multiplex cytokine analysis. Stool samples were collected by ileal loop and investigated for microbiome analysis by shotgun metagenomics. Serum, gut microbial lysate, and microbe-free fecal extract were subjected to metabolomic analysis by mass-spectrometry. Our results showed that the gut microbiome in geriatric animals had higher abundance of Archaeal and Proteobacterial species and lower Firmicutes than the young adults. Highly abundant microbes in the geriatric animals showed a direct association with plasma biomarkers of inflammation and immune activation such as neopterin, CRP, TNF, IL-2, IL-6, IL-8 and IFN-γ. Significant enrichment of metabolites that contribute to inflammatory and cytotoxic pathways was observed in serum and feces of geriatric animals compared to the young adults. We conclude that aging NHP undergo immunosenescence and age associated alterations in the gut microbiome that has a distinct metabolic profile. Aging NHP can serve as a model for investigating the relationship of the gut microbiome to particular age-associated comorbidities and for strategies aimed at modulating the microbiome.

Therapeutic assessment of N-formyl-methionyl-leucyl-phenylalanine (fMLP) in reducing periprosthetic joint infection

Despite many preventive measures, including prophylactic antibiotics, periprosthetic joint infection (PJI) remains a devastating complication following arthroplasty, leading to pain, suffering, morbidity and substantial economic burden. Humans have a powerful innate immune system that can effectively control infections, if alerted quickly. Unfortunately, pathogens use many mechanisms to dampen innate immune responses. The study hypothesis was that immunomodulators that can jumpstart and direct innate immune responses (particularly neutrophils) at the surgical site of implant placement would boost immune responses and reduce PJI, even in the absence of antibiotics. To test this hypothesis, N-formyl-methionyl-leucyl-phenylalanine (fMLP) (a potent chemoattractant for phagocytic leukocytes including neutrophils) was used in a mouse model of PJI with Staphylococcus aureus (S. aureus). Mice receiving intramedullary femoral implants were divided into three groups: i) implant alone; ii) implant + S. aureus; iii) implant + fMLP + S. aureus. fMLP treatment reduced S. aureus infection levels by ~ 2-Log orders at day 3. Moreover, fMLP therapy reduced infection-induced peri-implant periosteal reaction, focal cortical loss and areas of inflammatory infiltrate in mice distal femora at day 10. Finally, fMLP treatment reduced pain behaviour and increased weight-bearing at the implant leg in infected mice at day 10. Data indicated that fMLP therapy is a promising novel approach for reducing PJI, if administered locally at surgical sites. Future work will be toward further enhancement and optimisation of an fMLP-based therapeutic approach through combination with antibiotics and/or implant coating with fMLP.

Features of Neutrophils From Atopic and Non-Atopic Elite Endurance Runners

We collected peripheral blood from thirty-nine elite male endurance runners at rest (24 hours after the last exercise session) and used the Allergy Questionnaire for Athletes score and plasma specific IgE level to separate them into atopic and non-atopic athletes. Neutrophils obtained from atopic and non-atopic athletes were subsequently stimulated in vitro with fMLP (N-formyl-methionyl-leucyl-phenylalanine), LPS (lipopolysaccharide), or PMA (phorbol 12-myristate 13-acetate). Neutrophils from non-atopic runners responded appropriately to LPS, as evidenced by the production of pro (IL-8, TNF-α, and IL-6) and anti-inflammatory (IL-10) cytokines. Neutrophils from atopic elite runners exhibited lower responses to LPS stimulus as indicated by no increase in IL-1β, TNF-α, and IL-6 production. Neutrophils from non-atopic and atopic runners responded similarly to fMLP stimulation, indicating that migration function remained unaltered. Both groups were unresponsive to PMA induced reactive oxygen species (ROS) production. Training hours and training volume were not associated with neutrophil IgE receptor gene expression or any evaluated neutrophil function. Since non-atopic runners normally responded to LPS stimulation, the reduced neutrophil response to the stimuli was most likely due to the atopic state and not exercise training. The findings reported are of clinical relevance because atopic runners exhibit a constant decline in competition performance and are more susceptible to invading microorganisms.

Immune-Based Anti-Staphylococcal Therapeutic Approaches

Widespread methicillin-resistant Staphylococcus aureus (S. aureus) infections within community and healthcare settings are responsible for accelerated development of antibiotic resistance. As the antibiotic pipeline began drying up, alternative strategies were sought for future treatment of S. aureus infections. Here, we review immune-based anti-staphylococcal strategies that, unlike conventional antibiotics, target non-essential gene products elaborated by the pathogen. These strategies stimulate narrow or broad host immune mechanisms that are critical for anti-staphylococcal defenses. Alternative approaches aim to disrupt bacterial virulence mechanisms that enhance pathogen survival or induce immunopathology. Although immune-based therapeutics are unlikely to replace antibiotics in patient treatment in the near term, they have the potential to significantly improve upon the performance of antibiotics for treatment of invasive staphylococcal diseases.

O-GlcNAcylation and its role in the immune system

O-linked-N-acetylglucosaminylation (O-GlcNAcylation) is a type of glycosylation that occurs when a monosaccharide, O-GlcNAc, is added onto serine or threonine residues of nuclear or cytoplasmic proteins by O-GlcNAc transferase (OGT) and which can be reversibly removed by O-GlcNAcase (OGA). O-GlcNAcylation couples the processes of nutrient sensing, metabolism, signal transduction and transcription, and plays important roles in development, normal physiology and physiopathology. Cumulative studies have indicated that O-GlcNAcylation affects the functions of protein substrates in a number of ways, including protein cellular localization, protein stability and protein/protein interaction. Particularly, O-GlcNAcylation has been shown to have intricate crosstalk with phosphorylation as they both modify serine or threonine residues. Aberrant O-GlcNAcylation on various protein substrates has been implicated in many diseases, including neurodegenerative diseases, diabetes and cancers. However, the role of protein O-GlcNAcylation in immune cell lineages has been less explored. This review summarizes the current understanding of the fundamental biochemistry of O-GlcNAcylation, and discusses the molecular mechanisms by which O-GlcNAcylation regulates the development, maturation and functions of immune cells. In brief, O-GlcNAcylation promotes the development, proliferation, and activation of T and B cells. O-GlcNAcylation regulates inflammatory and antiviral responses of macrophages. O-GlcNAcylation promotes the function of activated neutrophils, but inhibits the activity of nature killer cells.

Xanthones, A Promising Anti-Inflammatory Scaffold: Structure, Activity, and Drug Likeness Analysis

Inflammation is the body's self-protective response to multiple stimulus, from external harmful substances to internal danger signals released after trauma or cell dysfunction. Many diseases are considered to be related to inflammation, such as cancer, metabolic disorders, aging, and neurodegenerative diseases. Current therapeutic approaches include mainly non-steroidal anti-inflammatory drugs and glucocorticoids, which are generally of limited effectiveness and severe side-effects. Thus, it is urgent to develop novel effective anti-inflammatory therapeutic agents. Xanthones, a unique scaffold with a 9H-Xanthen-9-one core structure, widely exist in natural sources. Till now, over 250 xanthones were isolated and identified in plants from the families Gentianaceae and Hypericaceae. Many xanthones have been disclosed with anti-inflammatory properties on different models, either in vitro or in vivo. Herein, we provide a comprehensive and up-to-date review of xanthones with anti-inflammatory properties, and analyzed their drug likeness, which might be potential therapeutic agents to fight against inflammation-related diseases.

Adjunctive Immunotherapeutic Efficacy of N-Formylated Internal Peptide of Mycobacterial Glutamine Synthetase in Mouse Model of Tuberculosis

BACKGROUND

Host-directed therapies are a comparatively new and promising method for the treatment of tuberculosis. A variety of host pathways, vaccines and drugs have the potential to provide novel adjunctive therapies for the treatment of tuberculosis. In this connection, we have earlier reported the immunotherapeutic potential of N-formylated N-terminal peptide of glutamine synthetase of Mycobacterim tuberculosis H37Rv (Mir SA and Sharma S, 2014). Now in the present study, we investigated the immunotherapeutic effect of N-terminally formylated internal-peptide 'f- MLLLPD' of mycobacterial glutamine synthetase (Rv2220) in mouse model of tuberculosis.

METHODS

The N-terminally formylated peptide, f-MLLLPD was tested for its potential to generate Reactive Oxygen Species (ROS) in murine neutrophils. Further, its therapeutic effect alone or in combination with anti-tubercular drugs was evaluated in mouse model of tuberculosis.

RESULTS

The f-MLLLPD peptide treatment alone and in combination with ATDs reduced the bacterial load (indicated as colony forming units) in lungs of infected mice by 0.58 (p<0.01) and 2.92 (p<0.001) log10 units respectively and in their spleens by 0.46 (p<0.05) and 2.46 (p<0.001) log10 units respectively. In addition, the observed histopathological results correlated well with the CFU data.

CONCLUSION

The results of the current study show that f-MLLLPD peptide confers an additional therapeutic efficacy to the anti-tuberculosis drugs.

Galectin-1 modulation of neutrophil reactive oxygen species production depends on the cell activation state

Here we report the effects of exogenous and endogenous galectin-1 (Gal-1) in modulating the functional responses of human and murine neutrophils at different stages of activation, i.e. naive, primed, and activated. Exposure to Gal-1 did not induce ROS production in either naive or N-formyl-methionyl-leucyl-phenylalanine-primed (fMLP; 10^-9 M) neutrophils. However, Gal-1 elicited a concentration-dependent ROS production in neutrophils activated with fMLP at concentrations ranging from 10^-8 M to 10^-6 M. Additional fMLP (10^-7 M) stimulation of fMLP-activated neutrophils increased ROS production, whose intensity was inversely related to the fMLP concentration used in the first activation step (10^-8 M to 10^-6 M), and was not influenced by the presence of Gal-1. Naive neutrophils treated with Gal-1 and then exposed to fMLP (10^-6 M) or phorbol-12-myristate-13-acetate (10^-7 M) produced less ROS, as compared to naive neutrophils not treated with Gal-1. Interestingly, these in vitro Gal-1 effects were associated with Gal-1 carbohydrate-binding activity and the ability to decrease FPR-1 (formyl peptide receptor 1) expression in naive human neutrophils. Conversely, positive ROS modulation by Gal-1 in activated neutrophils was not associated with FPR-1 expression but it was related to its carbohydrate recognition. In vitro, fMLP stimulation of Gal-1^-/- mouse neutrophils produced more ROS than fMLP stimulation of Gal-1^+/+ neutrophils and this effect may be associated with increased FPR-1 expression. Exogenous Gal-1 induced ROS production in Gal-1^-/- mouse neutrophils more effectively than in Gal-1^+/+ mouse neutrophils. Compared to Gal-1^+/+ mice, Gal-1^-/- mice exhibited lower bacterial load in the peritoneal fluid and peripheral blood, thus indicating a greater bactericidal activity in vivo. These findings demonstrate that endogenous Gal-1 restricts ROS generation that correlates with bacterial killing capacity in inflammatory neutrophils. Thus, endogenous and exogenous Gal-1 may either positively or negatively modulate the effector functions of neutrophils according to the cell activation stage.

Immunotherapeutic potential of an N-formylated peptide of Listeria monocytogenes in experimental tuberculosis

Objective: The current therapeutic regimens for tuberculosis (TB) are complex and involve the prolonged use of multiple antibiotics with diverse side effects that lead to therapeutic failure and bacterial resistance. The standard appliance of immunotherapy may aid as a powerful tool to combat the ensuing threat of TB. We have earlier reported the immunotherapeutic potential of N-formylated peptides of two secretory proteins of Mycobacterium tuberculosis H₃₇Rv. Here, we investigated the immunotherapeutic effect of an N-formylated peptide from Listeria monocytogenes in experimental TB. Methods: The N-terminally formylated listerial peptide with amino acid sequence 'f-MIGWII' was tested for its adjunctive therapeutic efficacy in combination with anti-tuberculosis drugs (ATDs) in the mouse model of TB. In addition, its potential to generate reactive oxygen species (ROS) in murine neutrophils was also evaluated. Results: The LemA peptide (f-MIGWII) induced a significant increase in the intracellular ROS levels of mouse neutrophils (p ≤ .05). The ATD treatment reduced the colony forming units (CFU) in lungs and spleen of infected mice by 2.39 and 1.67 log₁₀ units, respectively (p < .001). Treatment of the infected mice with combination of ATDs and LemA peptide elicited higher therapeutic efficacy over ATDs alone. The histopathological changes in the lungs of infected mice also correlated well with the CFU data. Conclusions: Our results clearly indicate that LemA peptide conferred an additional therapeutic effect when given in combination with the ATDss (p < .01) and hence can be used as adjunct to the conventional chemotherapy against TB.

A review of the fate of inhaled α-quartz in the lungs of rats

The distribution of dust particles within the lungs and their excretion are highly associated with their pulmonary toxicity. Literature was reviewed to discern pulmonary translocation pathways for inhaled α-quartz compared to those for inhaled TiO₂. Accordingly, it was hypothesized α-quartz particles in the alveoli were phagocytized by alveolar macrophages but silica-containing macrophages remained in the alveoli for longer time in contrast to the rapid elimination from the alveoli seen for TiO₂-containing macrophages. In addition, it was presumed that free silica particles are translocated in the interstitium, possibly through the cytoplasm of Type I epithelial cells, as observed with TiO₂. Free silica particles are presumed to be phagocytized by interstitial macrophages soon after the particles penetrate the interstitium; these dust cells are then translocated to the ciliated airway regions in the lumen through bronchus-associated lymphoid tissue (BALT). The pulmonary retention half-time of dust particles in rats exposed to α-quartz is several times longer than that of rats exposed to TiO₂, as long as the lung dust burden is ≈ 3 mg. The reduced pulmonary particle clearance ability in rats exposed to α-quartz aerosol is presumably attributed to the long-term retention of dust cells both in the alveoli and in the interstitium; this retention may be caused by the reduced chemotactic abilities of α-quartz-containing dust cells. However, the accumulation of α-quartz-containing dust cells in the lungs is not associated with the occurrence of pulmonary inflammation.

Eupatoriopicrin Inhibits Pro-inflammatory Functions of Neutrophils via Suppression of IL-8 and TNF-alpha Production and p38 and ERK 1/2 MAP Kinases

During chronic inflammation, neutrophils acting locally as effector cells not only activate antibacterial defense but also promote the inflammatory response. Interleukin 8 (IL-8), the main cytokine produced by activated neutrophils, positively correlates with the severity of respiratory tract diseases. By screening European plants traditionally used for treating respiratory tract diseases, we found that extracts of aerial parts of Eupatorium cannabinum inhibit IL-8 release from neutrophils. Using bioassay-guided fractionation, we identified five sesquiterpene lactones, eupatoriopicrin (1), 5'-deoxyeupatoriopicrin (2), hiyodorilactone A (3), 3-hydroxy-5'- O-acetyleupatoriopicrin = hiyodorilactone D (4), and hiyodorilactone B (5), that efficiently (IC₅₀ < 1 μM) inhibited IL-8 and TNF-α release in lipopolysaccharide (LPS)-stimulated human neutrophils. Moreover, all these sesquiterpene lactones suppressed the adhesion of human neutrophils to an endothelial monolayer by downregulating the expression of the β2 integrin CD11b/CD18 on the neutrophil surface. Furthermore, eupatoriopicrin efficiently suppressed LPS-induced phosphorylation of p38 MAPK and ERK and attenuated neutrophil infiltration in the thioglycolate-induced peritonitis model in mice. Altogether, these results demonstrate the potential of the sesquiterpene lactone eupatoriopicrin as a lead substance for targeting inflammation.

Formyl-methionyl-leucyl-phenylalanine Induces Apoptosis in Murine Neurons: Evidence for NO-Dependent Caspase-9 Activation

Formyl-methionyl-leucyl-phenylalanine (fMLP) may be present in the brain in the course of some infectious diseases of the central nervous system (CNS), although little is known about its role. This investigation was performed to study the effect of fMLP on neuron apoptosis. Our results showed that fMLP treatment of primary cultures of neurons was able to induce morphological features of apoptosis in cell cultures, as well as activation of the intrinsic apoptotic pathway, through the upregulation of caspase-9 and caspase-3. This effect contextually occurred to the pro-apoptotic protein Bax activation and cytochrome c release. The in vitro fMLP treatment was also able to induce, in a dose-dependent manner, the increase of inducible nitric oxide synthase (iNOS) expression accompanied by an up-regulation of nitric oxide (NO) release. When neuron cultures were pre-treated with 1400 W, a selective iNOS inhibitor, all of the apoptotic features were significantly reversed. Overall, these results demonstrated that fMLP treatment of neurons leads to intrinsic apoptosis activation, through iNOS expression regulation, suggesting a role for fMLP in CNS neurodegenerative processes.

Artificial opsonin enhances bacterial phagocytosis, oxidative burst and chemokine production by human neutrophils

Here, we describe the application of an 'artificial opsonin' to stimulate the innate immune response against Gram-positive bacteria. The artificial opsonin comprises a poly(L-lysine)-graft-poly(ethylene glycol) backbone displaying multiple copies of vancomycin and human IgG-Fc. The vancomycin targets bacteria by recognizing d-Ala-d-Ala-terminated peptides present in the bacterial cell wall. The human IgG-Fc antibody fragments serve as phagocyte recognition moieties that recognize the Fcγ cell surface receptors expressed by professional human phagocytes. Staphylococcus epidermidis RP62A, a biofilm-forming, methicillin-resistant strain, was utilized to investigate the effects of opsonization on phagocytosis, oxidative burst and IL-8 chemokine production by human neutrophils. Results show that opsonization of S. epidermidis RP62A with the artificial opsonin resulted in an ∼2-fold increase in neutrophil phagocytosis. Analysis of the cell supernatant found a 2- to 3-fold increase in neutrophil IL-8 secretion. The neutrophil oxidative burst was investigated using the oxidation-sensitive fluorophore dihydrorhodamine-123. Bacterial opsonization resulted in a 20% increase in fluorescence intensity, indicating a significant increase in the production of reactive oxygen species by the neutrophils. These studies suggest that artificial opsonins may be a novel immunostimulation therapeutic strategy to control infections caused by Gram-positive bacteria, particularly those that are known to be immune evasive and/or antibiotic resistant.

Applying label-free dynamic mass redistribution assay for studying endogenous FPR1 receptor signalling in human neutrophils

INTRODUCTION

The label-free dynamic mass redistribution-based assay (DMR) is a powerful method for studying signalling pathways of G protein-coupled receptors (GPCRs). Herein we present the label-free DMR assay as a robust readout for pharmacological characterization of formyl peptide receptors (FPRs) in human neutrophils.

METHODS

Neutrophils were isolated from fresh human blood and their responses to FPR1 and FPR2 agonists, i.e. compound 43, fMLF and WKYMVm were measured in a label-free DMR assay using Epic Benchtop System from Corning®. Obtained DMR traces were used to calculate agonist potencies.

RESULTS

The potencies (pEC₅₀) of fMLF, WKYMVm and compound 43, determined on human neutrophils using the label-free DMR assay were 8.63, 7.76 and 5.92, respectively. The DMR response to fMLF, but not WKYMVm and compound 43 could be blocked by the FPR1-specific antagonist cyclosporin H.

DISCUSSION

We conclude that the DMR assay can be used, and complements more traditional methods, to study the signalling and pharmacology of endogenous FPR receptors in human neutrophils.

Advanced Role of Neutrophils in Common Respiratory Diseases

Respiratory diseases, always being a threat towards the health of people all over the world, are most tightly associated with immune system. Neutrophils serve as an important component of immune defense barrier linking innate and adaptive immunity. They participate in the clearance of exogenous pathogens and endogenous cell debris and play an essential role in the pathogenesis of many respiratory diseases. However, the pathological mechanism of neutrophils remains complex and obscure. The traditional roles of neutrophils in severe asthma, chronic obstructive pulmonary diseases (COPD), pneumonia, lung cancer, pulmonary fibrosis, bronchitis, and bronchiolitis had already been reviewed. With the development of scientific research, the involvement of neutrophils in respiratory diseases is being brought to light with emerging data on neutrophil subsets, trafficking, and cell death mechanism (e.g., NETosis, apoptosis) in diseases. We reviewed all these recent studies here to provide you with the latest advances about the role of neutrophils in respiratory diseases.

LPS-induced modules of co-expressed genes in equine peripheral blood mononuclear cells

BACKGROUND

Lipopolysaccharide (endotoxin, LPS) is a strong inducer of the innate immune response. It is widespread in our environment, e.g. in house dust and contributes to asthma. Compared to humans, horses are even more sensitive to LPS. However, data on LPS effects on the equine transcriptome are very limited. Using RNA-seq we analysed LPS-induced differences in the gene expression in equine peripheral blood mononuclear cells at the gene and gene-network level in two half-sib families and one group of unrelated horses.

RESULTS

24 h-LPS challenge of equine immune cells resulted in substantial changes in the transcriptomic profile (1,265 differentially expressed genes) showing partial overlap with human data. One of the half-sib families showed a specific response different from the other two groups of horses. We also identified co-expressed gene modules that clearly differentiated 24 h-LPS- from non-stimulated samples. These modules consisted of 934 highly interconnected genes and included genes involved in the immune response (e.g. IL6, CCL22, CXCL6, CXCL2), however, none of the top ten hub genes of the modules have been annotated as responsive to LPS in gene ontology.

CONCLUSIONS

Using weighted gene co-expression network analysis we identified ten co-expressed gene modules significantly regulated by in vitro stimulation with LPS. Apart from 47 genes (5%) all other genes highly interconnected within the most up- and down-regulated modules were also significantly differentially expressed (FDR < 0.05). The LPS-regulated module hub genes have not yet been described as having a role in the immune response to LPS (e.g. VAT1 and TTC25).

The hepatocyte as a microbial product-responsive cell

Much research has focused on the responses to microbial products of immune cells such as monocytes, macrophages, and neutrophils. Although the liver is a primary response organ in various infections, relatively little is known about the antimicrobial responses of its major cell type, the hepatocyte. It is now known that the recognition of bacteria occurs via cell-surface proteins that are members of the Toll-like receptor (TLR) family. In addition, lipopolysaccharide (LPS) is bound by circulating LPS-binding protein (LBP) and presented to cell-surface CD14, which in turn interacts with TLR and transduces an intracellular signal. We investigated the CD14 and TLR2 responses of whole liver and isolated hepatocytes, and demonstrated that these cells can be induced to express the molecules necessary for responses to both Gram-positive and Gram-negative bacteria. Our findings may have clinical implications for pathological states such as sepsis.

Pd Nanoparticles Decorated N-Doped Graphene Quantum Dots@N-Doped Carbon Hollow Nanospheres with High Electrochemical Sensing Performance in Cancer Detection

The development of carbon based hollow-structured nanospheres (HNSs) materials has stimulated growing interest due to their controllable structure, high specific surface area, large void space, enhanced mass transport, and good biocompatibility. The incorporation of functional nanomaterials into their core and/or shell opens new horizons in designing functionalized HNSs for a wider spectrum of promising applications. In this work, we report a new type of functionalized HNSs based on Pd nanoparticles (NPs) decorated double shell structured N-doped graphene quantum dots (NGQDs)@N-doped carbon (NC) HNSs, with ultrafine Pd NPs and "nanozyme" NGQDs as dual signal-amplifying nanoprobes, and explore their promising application as a highly efficient electrocatalyst in electrochemical sensing of a newly emerging biomarker, i.e., hydrogen peroxide (H2O2), for cancer detection. Due to the synergistic effect of the robust and conductive HNS supports and catalytically active Pd NPs and NGQD in facilitating electron transfer, the NGQD@NC@Pd HNS hybrid material exhibits high electrocatalytic activity toward the direct reduction of H2O2 and can promote the electrochemical reduction reaction of H2O2 at a favorable potential of 0 V, which effectively restrains the redox of most electroactive species in physiological samples and eliminates interference signals. The resultant electrochemical H2O2 biosensor based hybrid HNSs materials demonstrates attractive performance, including low detection limit down to nanomole level, short response time within 2 s, as well as high sensitivity, reproducibility, selectivity, and stability, and have been used in real-time tracking of trace amounts of H2O2 secreted from different living cancer cells in a normal state and treated with chemotherapy and radiotherapy.

Formyl peptide receptor modulators: a patent review and potential applications for inflammatory diseases (2012-2015)

INTRODUCTION

The activation of leukocytes and the subsequent immune cascade play an essential role in sterile and infectious inflammation. Dysregulation of these immune responses or excess leukocyte activation can induce tissue damage, organ dysfunction and mortality. Formyl peptide receptors (FPRs) are functionally diverse pattern recognition receptors responsible for recognizing different endogenous damage-associated molecular patterns or exogenous pathogen-associated molecular patterns. FPRs mediate leukocyte activation during inflammation. FPR1 antagonists and FPR2 agonists have demonstrated significant anti-inflammatory effects based on in vitro and in vivo studies. An increasing number of synthesized compounds targeting FPRs, especially potential FPR1 antagonists and FPR2 agonists, have been disclosed in patents. Areas covered: This article summarizes the current pharmacology patents related to FPR family modulators and their therapeutic indications based on a review of patent applications disclosed between 2012 and 2015. Expert opinion: In this review, FPR1 modulators comprise β-1,3-glucan synthase inhibitors containing an FPR ligand moiety, template-fixed peptidomimetics, cyclosporin H, and dipeptide derivatives. FPR2 modulators include phenylurea, bridged spiro[2.4]heptane ester, naphthalene, aminotriazole, polycyclic pyrrolidine-2,5-dione, imidazolidine-2,4-dione, (2-ureidoacetamido)alkyl, amide, oxazolyl-methylether, oxazole, thiazole, and crystalline potassium salt derivatives. These compounds have potential applications for human conditions such as inflammatory lung diseases, ischemia-reperfusion injury, sepsis, inflammatory bowel disease, and wound healing. FPRs are emerging as important targets for treating leukocyte-dominant inflammation.

[Modulating Effect of Extracellular HSP70 on Generation of Reactive Oxigen Species in Populations of Phagocytes]

Reactive oxygen species (ROS) produced by phagocytic cells of the innate immune system play an important role in the first line of defense protecting the host from pathogens. The NADPH oxidase multi-subunit complex is the main source of ROS in all types of the phagocytes. Formation of the membrane-associated enzyme complex and its activity are dependent on many different factors controlling both intensification and suppression of the ROS production rate. However, the evidences are emerging in recent years indicating existence of poorly studied mechanisms of restriction of ROS generation level in phagocytes directed at protection of host tissues in the sites of inflammation from destruction caused by the oxygen free radicals. Our previous data and results of other authors demonstrate that a mechanism of the limitation of ROS production by phagocytes may by connected with immunomodulating activity of extracellular pool. of HSP70. In the present work, we used inhibitors of NADPH oxidase and in vitro cultures of different phagocytes to study a possible relationship between down-regulating effect of exogenous HSP70 on ROS generation and the interaction of the protein with the enzyme subunits. Our results confirmed the literature data concerning the ability of extracellular HSP70 to modulate NADPH oxidase activity and demonstrated for the first time an inhibitory effect of the protein on intracellular ROS generation in phagocytes.

Altered Innate Immune Responses in Neutrophils from Patients with Well- and Suboptimally Controlled Asthma

BACKGROUND

Respiratory infections are a major cause of asthma exacerbations where neutrophilic inflammation dominates and is associated with steroid refractory asthma. Structural airway cells in asthma differ from nonasthmatics; however it is unknown if neutrophils differ. We investigated neutrophil immune responses in patients who have good (AGood) and suboptimal (ASubopt) asthma symptom control.

METHODS

Peripheral blood neutrophils from AGood (ACQ < 0.75, n = 11), ASubopt (ACQ > 0.75, n = 7), and healthy controls (HC) (n = 9) were stimulated with bacterial (LPS (1 μg/mL), fMLF (100 nM)), and viral (imiquimod (3 μg/mL), R848 (1.5 μg/mL), and poly I:C (10 μg/mL)) surrogates or live rhinovirus (RV) 16 (MOI1). Cell-free supernatant was collected after 1 h for neutrophil elastase (NE) and matrix metalloproteinase- (MMP-) 9 measurements or after 24 h for CXCL8 release. Results. Constitutive NE was enhanced in AGood neutrophils compared to HC. fMLF stimulated neutrophils from ASubopt but not AGood produced 50% of HC levels. fMLF induced MMP-9 was impaired in ASubopt and AGood compared to HC. fMLF stimulated CXCL8 but not MMP-9 was positively correlated with FEV1 and FEV1/FVC. ASubopt and AGood responded similarly to other stimuli.

CONCLUSIONS

Circulating neutrophils are different in asthma; however, this is likely to be related to airflow limitation rather than asthma control.

fMLP-Induced IL-8 Release Is Dependent on NADPH Oxidase in Human Neutrophils

N-Formyl-methionyl-leucyl-phenylalanine (fMLP) and platelet-activating factor (PAF) induce similar intracellular signalling profiles; but only fMLP induces interleukin-8 (IL-8) release and nicotinamide adenine dinucleotide phosphate reduced (NADPH) oxidase activity in neutrophils. Because the role of ROS on IL-8 release in neutrophils is until now controversial, we assessed if NADPH oxidase is involved in the IL-8 secretions and PI3K/Akt, MAPK, and NF-κB pathways activity induced by fMLP. Neutrophils were obtained from healthy volunteers. IL-8 was measured by ELISA, IL-8 mRNA by qPCR, and ROS production by luminol-amplified chemiluminescence, reduction of ferricytochrome c, and FACS. Intracellular pH changes were detected by spectrofluorescence. ERK1/2, p38 MAPK, and Akt phosphorylation were analysed by immunoblotting and NF-κB was analysed by immunocytochemistry. Hydroxy-3-methoxyaceto-phenone (HMAP), diphenyleneiodonium (DPI), and siRNA Nox2 reduced the ROS and IL-8 release in neutrophils treated with fMLP. HMAP, DPI, and amiloride (a Na⁺/H⁺ exchanger inhibitor) inhibited the Akt phosphorylation and did not affect the p38 MAPK and ERK1/2 activity. DPI and HMAP reduced NF-κB translocation induced by fMLP. We showed that IL-8 release induced by fMLP is dependent on NADPH oxidase, and ROS could play a redundant role in cell signalling, ultimately activating the PI3K/Akt and NF-κB pathways in neutrophils.

Role of formic receptors in soluble urokinase receptor-induced human vascular smooth muscle migration

BACKGROUND

Vascular smooth muscle cell (VSMC) migration in response to urokinase is dependent on binding of the urokinase molecule to the urokinase plasminogen receptor (uPAR) and cleavage of the receptor. The aim of this study was to examine the role of the soluble uPAR (suPAR) in VSMC migration.

METHODS

Human VSMCs were cultured in vitro. Linear wound and Boyden microchemotaxis assays of migration were performed in the presence of suPAR. Inhibitors to G-protein signaling and kinase activation were used to study these pathways. Assays were performed for mitogen-activated protein kinase and epidermal growth factor receptor activation.

RESULTS

suPAR induced concentration-dependent migration of VSMC, which was G protein-dependent and was blocked by Gαi and Gβγ inhibitors. Removal of the full uPAR molecule by incubation of the cells with a phospholipase did not interfere with this response. suPAR induced ERK1/2, p38(MAPK), and c-Jun N-terminal kinase [JNK] activation in a Gαi/Gβγ-dependent manner, and interruption of these signaling pathways prevented suPAR-mediated migration. suPAR activity was independent of plasmin activity. suPAR did not activate epidermal growth factor receptor. Interruption of the low affinity N-formyl-Met-Leu-Phe receptor (FPRL1) but not high affinity N-formyl-Met-Leu-Phe receptor (FPR) prevented cell migration and activation in response to suPAR. suPAR increased matrix metalloproteinase-2 expression and activity, and this was dependent on the low affinity N-formyl-Met-Leu-Phe receptor (FPRL1) and ERK1/2.

CONCLUSIONS

suPAR induces human smooth muscle cell activation and migration independent of the full uPAR through activation of the G protein-coupled receptor FPRL1, which is not linked to the plasminogen activation cascade.

Enhancing the interaction between annexin-1 and formyl peptide receptors regulates microglial activation to protect neurons from ischemia-like injury

As the immune cells of the brain, microglia are crucial for the maintenance of brain function. The aims of the present study were to determine whether and how annexin-1 is able to affect microglial phenotype and migration in the lesion microenvironment. In the current experiment, we enhanced the interaction between annexin-1 and formyl peptide receptors in microglia and analyzed the function. We found that annexin-1 could polarize microglia to a beneficial phenotype and promote microglial migration to protect neurons from ischemia-like injury, and the annexin-1-mediated neuroprotective effect was dependent on the release of glutamate and ATP from the injured neurons.

The Contractile Response of Isolated Small Pulmonary Arteries Induced by Activated Macrophages

To test whether macrophages can play any role in hypoxic pulmonary vasoconstriction, we tested the in vitro response of rings from small pulmonary arteries to the activation of macrophages by FMLP, a substance stimulating predominantly membrane-bound NADPH oxidase. A small vessel myograph was used to measure the responses of rings from small pulmonary arteries (300-400 μm) isolated from rat lungs. Rings from 5 rats were placed into both chambers of the myograph. The vessels were stabilized for 40 min and then normalized by automatic stretching to a wall tension equivalent to the intravascular pressure 30 mm Hg. At the start of each experiment, vessels were exposed to 80 mM K+ to obtain maximal contractile response, which was used to normalize subsequent contractile responses. 2x106 viable macrophages, obtained by peritoneal lavage, were added into one chamber, then 5 μM FMLP was administrated to both chambers and the tension measurement was started. The hydrogen peroxide concentration produced by stimulated macrophages was measured luminometrically. The concentrations of H2O2 in specimens from chambers containing activated macrophages rose from 3.5±1.5 nM to 110±28 nM within 25 min of stimulation, while FMLP itself didn’t increase the H2O2 concentration from the baseline value (4.5±3 nM) in samples from control chambers. After FMLP administration, the tension of the vessel rings in the presence of macrophages reached 0.23±0.07 of maximal contractile response, it did not change in controls. The addition of ROS scavenger 4-hydroxy-TEMPO blocked the contractile response to the activation of macrophages. We conclude that the activation of macrophages stimulates the contraction of small pulmonary arteries and that this contraction is probably mediated by reactive oxygen species.

Role of MHC class Ib molecule, H2-M3 in host immunity against tuberculosis

The MHC class I family comprises both classical (class Ia) and non-classical (class Ib) members. While the prime function of classical MHC class I molecules (MHC class Ia) is to present peptide antigens to pathogen-specific cytotoxic T cells, non-classical MHC-I (MHC class Ib) antigens perform diverse array of functions in both innate and adaptive immunity. Vaccines against intracellular pathogens such as Mycobacterium tuberculosis need to induce strong cellular immune responses. Recent studies have shown that MHC class I molecules play an important role in the protective immune response to M. tuberculosis infection. Both MHC Ia-restricted and MHC class Ib-restricted M. tuberculosis -reactive CD8(+) T cells have been identified in humans and mice, but their relative contributions to immunity is still uncertain. Unlike MHC class Ia-restricted CD8(+) T cells, MHC class Ib-restricted CD8(+) T cells are constitutively activated in naive animals and respond rapidly to infection challenge, hence filling the temporal gap between innate and adaptive immunity. The present review article summarizes the general host immunity against M. tuberculosis infection highlighting the possible role of MHC class Ib molecule, H2-M3 and their ligands (N-formylated peptides) in protection against tuberculosis.

Mechanistic overview of reactive species-induced degradation of the endothelial glycocalyx during hepatic ischemia/reperfusion injury

Endothelial cells are covered by a delicate meshwork of glycoproteins known as the glycocalyx. Under normophysiological conditions the glycocalyx plays an active role in maintaining vascular homeostasis by deterring primary and secondary hemostasis and leukocyte adhesion and by regulating vascular permeability and tone. During (micro)vascular oxidative and nitrosative stress, which prevails in numerous metabolic (diabetes), vascular (atherosclerosis, hypertension), and surgical (ischemia/reperfusion injury, trauma) disease states, the glycocalyx is oxidatively and nitrosatively modified and degraded, which culminates in an exacerbation of the underlying pathology. Consequently, glycocalyx degradation due to oxidative/nitrosative stress has far-reaching clinical implications. In this review the molecular mechanisms of reactive oxygen and nitrogen species-induced destruction of the endothelial glycocalyx are addressed in the context of hepatic ischemia/reperfusion injury as a model disease state. Specifically, the review focuses on (i) the mechanisms of glycocalyx degradation during hepatic ischemia/reperfusion, (ii) the molecular and cellular players involved in the degradation process, and (iii) its implications for hepatic pathophysiology. These topics are projected against a background of liver anatomy, glycocalyx function and structure, and the biology/biochemistry and the sources/targets of reactive oxygen and nitrogen species. The majority of the glycocalyx-related mechanisms elucidated for hepatic ischemia/reperfusion are extrapolatable to the other aforementioned disease states.

Selective loss of chemokine receptor expression on leukocytes after cell isolation

Chemokine receptors are distinctively exposed on cells to characterize their migration pattern. However, little is known about factors that may regulate their expression. To determine the optimal conditions for an accurate analysis of chemokine receptors, we compared the expression of CCR2, CCR4, CCR5, CCR6, CXCR3 and CXCR4 on different leukocyte subsets using whole blood (WB) plus erythrocyte lysis and density gradient isolation (Ficoll). Most WB monocytes were CCR2+ (93.5 ± 2.9%) whereas 32.8 ± 6.0% of monocytes from Ficoll-PBMC expressed CCR2 (p<0.001). Significant reductions of CCR6 and CXCR3 on monocytes were also observed after Ficoll isolation (WB: 46.4 ± 7.5% and 57.1 ± 5.5%; Ficoll: 29.5 ± 2.2% and 5.4 ± 4.3% respectively) (p<0.01). Although comparable percentages of WB and Ficoll-PBMC monocytes expressed CCR4, CCR5 and CXCR4, Ficoll isolation significantly reduced the levels of CXCR4 (WB: MFI 5 ± 0.4 and Ficoll: MFI 3.3 ± 0.1) (p<0.05). Similarly to monocytes, CCR2, CXCR3 and CXCR4 were also reduced on lymphocytes. In addition, Ficoll isolation significantly reduced the percentage of CCR4 positive lymphocytes (WB: 90.2 ± 4.5% and Ficoll: 55 ± 4.1%) (p<0.01). The loss of expression of chemokine receptors after isolation of monocytes was not dependent on either the anticoagulant or the density gradient method. It was irreversible and could not be restored by LPS activation or in vitro macrophage differentiation. Experiments tagged with anti-CCR2 antibodies prior to density gradient isolation demonstrated that Ficoll internalized chemokine receptors. The method for cell isolation may alter not only the expression of certain chemokine receptors but also the respective functional migration assay. The final choice to analyze their expression should therefore depend on the receptor to be measured.

Plasma membrane damage sensing and repairing. Role of heterotrimeric G-proteins and the cytoskeleton

Different toxic agents, derived from bacteria, viruses or cells of the immune system, as well as mechanical forces generated during cell locomotion are able to open pores in the cell plasma membrane. Most of these biological agents operate through specific receptors. We studied the formation and resealing of the "non-specific" plasma membrane pores generated by the mild non-ionic detergent Triton X-100. In HL-60-derived granulocytic cells plasma membrane pore opening after a 1-h treatment with Triton X-100 is documented by entry into the cell of the membrane impermeant dye ethidium bromide. As a consequence of the opening of pores the intracellular K(+) concentration falls dramatically, the cytosolic pH diminishes and the cell membrane is depolarized. Furthermore the cells acquire a polarized morphology, demonstrating the involvement of the actin cytoskeleton. At the Triton concentration used the membrane lesions are progressively repaired and by 8h the impermeability to ethidium bromide is restored and the intracellular K(+) concentration is virtually normal. Following treatments with Triton+Pertussis toxin, Triton+Cytochalasin, or Triton+Pertussis toxin+Cytochalasin the progress of membrane repair is dramatically slowed and is no longer completed by 8h. It is concluded that the membrane damage activates pertussis-sensitive G-proteins which likely act as sensors of the damage, while both G-proteins and the actin cytoskeleton are involved in the membrane repair mechanism.

Moderate increase in temperature may exacerbate neuroinflammatory processes in the brain: human cell culture studies

The effect of a moderate, physiologically relevant rise in temperature on several neuroinflammatory parameters was investigated in vitro using human cell lines and cultured human astrocytes. A two degree Celsius rise in temperature was found to enhance the neurotoxicity of microglia-like and astrocytic cells, increase the release of monocyte chemotactic protein (MCP)-1 by activated human monocytic THP-1 cells and amplify the generation of reactive oxygen intermediates by differentiated HL-60 myelocytic cells. Moderate increases in body temperature may exacerbate neuroinflammation and neuronal injury in chronic neurodegenerative disorders. Hence, therapies aimed at lowering the body temperature could be used to slow down the progression of such diseases.

Reoxygenation attenuates the adhesion of neutrophils to microvascular endothelial cells

In humans, the pathophysiological inflammation response subsequent to hypoxia and reoxygenation often leads to systemic inflammation and multiorgan failure. We applied a newly developed static interaction model using human polymorphonuclear neutrophils and microvascular endothelial cells to clarify the role of hypoxia and hypoxia/reoxygenation in vitro. Human dermal microvascular endothelial cell cultures (n = 7) were exposed to hypoxia and different reoxygenation periods and the adherence rate of neutrophils to the endothelial cells as well as to the protein matrix on the culture slide surface were determined by quantitative microscopy. Hypoxia clearly triggered neutrophil adhesion to human dermal microvascular endothelial cells whereas additional reoxygenation significantly decreased neutrophil adhesion. These in vitro findings suggest that systemic inflammation caused by increased neutrophil adherence to the microvascular endothelium is already initiated by hypoxia rather than by subsequent reoxygenation.

Maitake beta-glucan promotes recovery of leukocytes and myeloid cell function in peripheral blood from paclitaxel hematotoxicity

Bone marrow myelotoxicity is a major limitation of chemotherapy. While granulocyte colony stimulating factor (G-CSF) treatment is effective, alternative approaches to support hematopoietic recovery are sought. We previously found that a beta-glucan extract from maitake mushroom Grifola frondosa (MBG) enhanced colony forming unit-granulocyte monocyte (CFU-GM) activity of mouse bone marrow and human hematopoietic progenitor cells (HPC), stimulated G-CSF production and spared HPC from doxorubicin toxicity in vitro. This investigation assessed the effects of MBG on leukocyte recovery and granulocyte/monocyte function in vivo after dose intensive paclitaxel (Ptx) in a normal mouse. After a cumulative dose of Ptx (90-120 mg/kg) given to B6D2F1mice, daily oral MBG (4 or 6 mg/kg), intravenous G-CSF (80 microg/kg) or Ptx alone were compared for effects on the dynamics of leukocyte recovery in blood, CFU-GM activity in bone marrow and spleen, and granulocyte/monocyte production of reactive oxygen species (ROS). Leukocyte counts declined less in Ptx + MBG mice compared to Ptx-alone (p = 0.024) or Ptx + G-CSF treatment (p = 0.031). Lymphocyte levels were higher after Ptx + MBG but not Ptx + G-CSF treatment compared to Ptx alone (p < 0.01). MBG increased CFU-GM activity in bone marrow and spleen (p < 0.001, p = 0.002) 2 days after Ptx. After two additional days (Ptx post-day 4), MBG restored granulocyte/monocyte ROS response to normal levels compared to Ptx-alone and increased ROS response compared to Ptx-alone or Ptx + G-CSF (p < 0.01, both). The studies indicate that oral MBG promoted maturation of HPC to become functionally active myeloid cells and enhanced peripheral blood leukocyte recovery after chemotoxic bone marrow injury.

CD44 deficiency is associated with enhanced Escherichia coli-induced proinflammatory cytokine and chemokine release by peritoneal macrophages

CD44 is involved in several immune responses, such as cellular adhesion, migration, proliferation, and activation. Peritonitis is an important cause of sepsis, and Escherichia coli is one of the major pathogens involved therein. We sought to determine the role of CD44 in the host response to E. coli-induced abdominal sepsis and to assess the function of CD44 in the activation of primary peritoneal macrophages by E. coli or lipopolysaccharide (LPS) purified from this bacterium by using wild-type (WT) and CD44 knockout (KO) mice. CD44 KO mice already demonstrated enhanced CXC chemokine levels in peritoneal lavage fluid at 6 h after infection, whereas tumor necrosis factor alpha (TNF-alpha) and interleukin-6 levels were elevated at 20 h postinfection. In line with this, CD44 KO mouse peritoneal macrophages released more TNF-alpha and macrophage inflammatory protein 2 (MIP-2) than did WT cells upon stimulation with E. coli or LPS in the presence of autologous serum. In contrast, plasma TNF-alpha levels were lower in CD44 KO mice and CD44 KO blood leukocytes secreted similar amounts of TNF-alpha and MIP-2 upon ex vivo incubation with E. coli or LPS. The proinflammatory phenotype of CD44 KO macrophages was not associated with an altered expression of inhibitors of Toll-like receptor signaling, whereas it could be partially reversed by addition of WT serum. CD44 deficiency did not impact on leukocyte recruitment into the peritoneal cavity or organ failure. These data suggest that CD44 differentially influences cytokine and chemokine release by different leukocyte subsets.

Helicobacter pylori Hp(2-20) promotes migration and proliferation of gastric epithelial cells by interacting with formyl peptide receptors in vitro and accelerates gastric mucosal healing in vivo

Helicobacter pylori-derived peptide RpL1 aa 2-20 (Hp(2-20)) in addition to its antimicrobial action exerts several immunomodulatory effects in eukaryotic cells by interacting with formyl peptide receptors (FPRs). It has recently been shown that activation of FPRs facilitates intestinal epithelial cell restitution. We investigated whether Hp(2-20) induces healing of injured gastric mucosa and assessed the mechanisms underlying any such effect. We investigated the expression of FPRs in two gastric epithelial cell lines (MKN-28 and AGS) at mRNA and protein level. To determine whether FPRs were functional we performed chemotaxis experiments and proliferation assays and studied the Hp(2-20)-activated downstream signaling pathway. The effect of Hp(2-20) on mucosal healing was evaluated in rats after indomethacin-induced injury. Here we show that: (1) FPRs were expressed in both cell lines; (2) Hp(2-20) stimulated migration and proliferation of gastric epithelial cells; (3) this effect was specifically mediated by formyl peptide receptor-like 1 (FPRL1) and FPRL2 and was associated with activation of FPR-related downstream signaling pathways; (4) Hp(2-20) up-regulated the expression and secretion of vascular endothelial growth factor; and (5) Hp(2-20) accelerated healing of rat gastric mucosa after injury brought about by indomethacin at both the macroscopic and microscopic levels. In conclusion, by interacting with FRPL1 and FPRL2, H. pylori-derived Hp(2-20) induces cell migration and proliferation, as well as the expression of vascular endothelial growth factor, thereby promoting gastric mucosal healing. This study provides further evidence of the complexity of the relationship between H. pylori and human gastric mucosa, and it suggests that a bacterial product may be used to heal gastric mucosal injury.

An fMLP receptor is involved in activation of phagocytosis by hemocytes from specific insect species

In mammalian phagocytes, the bacterial formylated peptide fMLP functions both as a potent enhancer of phagocytosis and chemoattractant. fMLP has been reported to be chemotactic for hemocytes of two marine invertebrates, and of the insect Manduca sexta (Lepidoptera). Whether fMLP is also able to activate phagocytosis has not been explored in hemocytes of any invertebrate. To determine the effect of fMLP on insect hemocyte phagocytosis, in vitro phagocytosis assays were performed with hemocytes from the insects: Gromphadorhina portentosa (Blattodea), Acheta domesticus (Orthoptera), Zophobas morio (Coleoptera), and Galleria mellonella (Lepidoptera). Phagocytosis of latex, zymosan (yeast), Gram-positive and Gram-negative bacteria was measured by flow cytometry, in the presence of increasing fMLP concentrations. G. portentosa hemocytes showed no enhancement of phagocytosis by fMLP. A. domesticus hemocytes had increased phagocytosis of latex and Gram-negative bacteria in the presence of fMLP. Z. morio hemocytes increased phagocytosis of latex, yeast, and Gram-negative bacteria after fMLP stimulation. Galleria mellonella hemocytes increased phagocytosis of latex after fMLP stimulation. Treating hemocytes with Pertussis toxin, a known inhibitor of the signaling pathway initiated by the mammalian fMLP receptor, returned phagocytosis to basal levels. Also, hemocytes from all insect species tested presented a similar chemotactic response to fMLP. These data suggest that, whereas the ability of hemocytes to chemotactically-respond to fMLP is conserved in insects ranging from Blattodea to Lepidoptera, the ability to respond to fMLP by activating phagocytosis is restricted to specific insect species.

1-Methyl and 1-(2-hydroxyalkyl)-5-(3-alkyl/cycloalkyl/phenyl/naphthylureido)-1H-pyrazole-4-carboxylic acid ethyl esters as potent human neutrophil chemotaxis inhibitors

In this paper we report the synthesis and the chemotaxis inhibitory activity of a number of 1H-pyrazole-4-carboxylic acid ethyl esters 2 functionalized in N1 with a methyl group or different hydroxyalkyl chains and in position 5 with a series of 3-substituted urea groups. These compounds were designed as development of previous pyrazole-urea derivatives that resulted potent IL8-induced neutrophil chemotaxis inhibitors in vitro. Most of the new compounds revealed a potent inhibition of both IL8- and fMLP-OMe-stimulated neutrophil chemotaxis. The most active compounds in the fMLP-OMe induced chemotaxis test showed IC(50) in the range 0.19 nM-2 microM; but we observed a very strong inhibition in the IL8-induced chemotaxis test, having the most active compounds IC(50) at pM concentrations. In vivo compounds 2e and 2f, although to a lesser extent, at 50mg/kg os decreased granulocyte infiltration in zymosan-induced peritonitis in mice.