Understanding COVID-19 progression with longitudinal peripheral blood mononuclear cell proteomics: Changes in the cellular proteome over time

The clinical presentation of COVID-19 is highly variable, and understanding the underlying biological processes is crucial. This study utilized a proteomic analysis to investigate dysregulated processes in the peripheral blood mononuclear cells of patients with COVID-19 compared to healthy volunteers. Samples were collected at different stages of the disease, including hospital admission, after 7 days of hospitalization, and 30 days after discharge. Metabolic pathway alterations and increased abundance of neutrophil-related proteins were observed in patients. Patients progressing to critical illness had significantly low-abundance proteins in the pentose phosphate and glycolysis pathways compared with those presenting clinical recovery. Important biological processes, such as fatty acid concentration and glucose metabolism disorder, remained altered even after 30 days of hospital discharge. Temporal proteomic changes revealed distinct pathways in critically ill and non-critically ill patients. Our study emphasizes the significance of longitudinal cellular proteomic studies in identifying disease progression-related pathways and persistent protein changes post-hospitalization.

ALTERED LEVELS OF H3K9AC, H3K4ME3, AND H3K27ME3 IN PROMOTERS OF DIFFERENTIALLY EXPRESSED GENES RELATED TO INNATE IMMUNE RESPONSE IN SEPTIC PATIENTS WITH DIFFERENT CLINICAL OUTCOMES

ABSTRACT

Sepsis is one of the leading causes of morbidity and mortality worldwide. Monocytes seem to undergo functional reprogramming during sepsis, resulting in dysregulated host immune response. To clarify this dysregulation mechanism, we investigated three histone modifications found in promoters of genes involved in innate immune response, and associated these findings with gene transcription in septic patients. These results were compared with public transcriptome data of the target genes and epigenetic enzymes that modulate the histone modifications. We used peripheral blood mononuclear cell from surviving and nonsurviving septic patients, and healthy volunteers to evaluate the expression of genes involved in innate immune response and the enrichment of H3K9ac, H3K4me3, and H3K27me3 in their promoters, by RT-qPCR and ChIP, respectively. Finally, we used transcriptome data sets to validate our findings. We found alterations in the chromatin enrichment of different genes, with an increase in H3K9ac in the anti-inflammatory cytokine IL-10 and the antimicrobial gene FPR1 , as well as an increase in H3K27me3 in the IL-10 and HLA-DR promoter in nonsurvivors septic patients when compared with survivors. These alterations were partially associated with the gene expression profile. In addition, we found moderate to strong correlation between gene transcription and the enzymes that modulate these histone modifications in the transcriptome data sets. Our study, one of the pioneering by evaluating septic patients' samples, suggests that epigenetic enzymes modulate the prevalent histone marks in promoters of genes involved in the immune-inflammatory response, altering the transcription of these specific genes during sepsis. Furthermore, nonsurviving sepsis patients have a more pronounced epigenetic dysregulation compared with survivors, suggesting a more dysfunctional response.

Immune Profile and Body Composition of Independent Oldest Old: The Longevous Project

INTRODUCTION

Immunosenescence is associated with changes in lymphocyte function, thymus atrophy, and a chronic inflammatory process referred to as "inflammaging," which may in part be linked to eating disorders.

OBJECTIVE

The aim of the study was to determine the prevalence rate of immunological alterations, including immune risk profile (IRP), and their association with body composition in the oldest old individuals.

METHODS

A cross-sectional study of 201 older adults aged 80 years and over, able to walk unaided, with no cognitive or immunological impairment, and with no serious diseases was conducted. Blood samples were collected between 2012 and 2014 during the morning period, and the following tests were conducted: urea, creatinine, hemogram, fasting glucose, glycated hemoglobin, transferrin, albumin, 25-OH vitamin D, and high-sensitivity CRP. Plasma cytokines were measured and mononuclear cell counts were performed by flow cytometry. Anthropometric measurements and densitometry using dual-energy X-ray absorptiometry (DXA) were performed to assess body composition.

RESULTS

Mean age was 84.4 ± 3.7 years, and the numbers of T cells were CD4, 784.0 cell/µL; CD8, 371.0 cell/µL; and CD4/CD8, 2.4. The rate of CD4/CD8 <1 (IRP) was 9.4%, CD4/CD8 1-5 was 85.6%, while CD4/CD8 >5 was only 5.5%. CRP, tumor necrosis factor, IL1, IL4, IL6, and IL10 variables showed a high coefficient of variation but low mean values of 1.1 ± 3.1 mg/L for CRP (reference range <3 mg/L) and 3.9 ± 5.0 pg/mL for IL6 (reference range <7.0 pg/mL). The same pattern was found for all other inflammatory variables assessed, characterizing a population whose values indicated low level of inflammation, considering age. Lean mass, as measured by DXA, was higher in men than in women, while the inverse was found for fat % (p < 0.001). A positive association between CRP values and DXA fat % (p value: 0.007, r: 0.49) and a negative association between CRP values and DXA lean mass (p value: 0.046, r:-0.37) was observed.

CONCLUSION

In the independent oldest old, IRP rate proved low and high-sensitivity CRP was shown to be associated with body composition.

Glucose metabolism is upregulated in the mononuclear cell proteome during sepsis and supports endotoxin-tolerant cell function

Metabolic adaptations shape immune cell function. In the acute response, a metabolic switch towards glycolysis is necessary for mounting a proinflammatory response. During the clinical course of sepsis, both suppression and activation of immune responses take place simultaneously. Leukocytes from septic patients present inhibition of cytokine production while other functions such as phagocytosis and production of reactive oxygen species (ROS) are preserved, similarly to the in vitro endotoxin tolerance model, where a first stimulation with lipopolysaccharide (LPS) affects the response to a second stimulus. Here, we sought to investigate how cellular metabolism is related to the modulation of immune responses in sepsis and endotoxin tolerance. Proteomic analysis in peripheral blood mononuclear cells (PBMCs) from septic patients obtained at intensive care unit admission showed an upregulation of proteins related to glycolysis, the pentose phosphate pathway (PPP), production of ROS and nitric oxide, and downregulation of proteins in the tricarboxylic acid cycle and oxidative phosphorylation compared to healthy volunteers. Using the endotoxin-tolerance model in PBMCs from healthy subjects, we observed increased lactate production in control cells upon LPS stimulation, while endotoxin-tolerant cells presented inhibited tumor necrosis factor-α and lactate production along with preserved phagocytic capacity. Inhibition of glycolysis and PPP led to impairment of phagocytosis and cytokine production both in control and in endotoxin-tolerant cells. These data indicate that glucose metabolism supports leukocyte functions even in a condition of endotoxin tolerance.

Repurposing of Clinically Approved Poly-(ADP-Ribose) Polymerase Inhibitors for the Therapy of Sepsis

ABSTRACT

Sepsis' pathogenesis involves multiple mechanisms that lead to a dysregulation of the host's response. Significant efforts have been made in search of interventions that can reverse this situation and increase patient survival. Poly (ADP-polymerase) (PARP) is a constitutive nuclear and mitochondrial enzyme, which functions as a co-activator and co-repressor of gene transcription, thus regulating the production of inflammatory mediators. Several studies have already demonstrated an overactivation of PARP1 in various human pathophysiological conditions and that its inhibition has benefits in regulating intracellular processes. The PARP inhibitor olaparib, originally developed for cancer therapy, paved the way for the expansion of its clinical use for nononcological indications. In this review we discuss sepsis as one of the possible indications for the use of olaparib and other clinically approved PARP inhibitors as modulators of the inflammatory response and cellular dysfunction. The benefit of olaparib and other clinically approved PARP inhibitors has already been demonstrated in several experimental models of human diseases, such as neurodegeneration and neuroinflammation, acute hepatitis, skeletal muscle disorders, aging and acute ischemic stroke, protecting, for example, from the deterioration of the blood-brain barrier, restoring the cellular levels of NAD+, improving mitochondrial function and biogenesis and, among other effects, reducing oxidative stress and pro-inflammatory mediators, such as TNF-α, IL1-β, IL-6, and VCAM1. These data demonstrated that repositioning of clinically approved PARP inhibitors may be effective in protecting against hemodynamic dysfunction, metabolic dysfunction, and multiple organ failure in patients with sepsis. Age and gender affect the response to PARP inhibitors, the mechanisms underlying the lack of many protective effects in females and aged animals should be further investigated and be cautiously considered in designing clinical trials.

Combined Transcriptome and Proteome Leukocyte's Profiling Reveals Up-Regulated Module of Genes/Proteins Related to Low Density Neutrophils and Impaired Transcription and Translation Processes in Clinical Sepsis

Sepsis is a global health emergency, which is caused by various sources of infection that lead to changes in gene expression, protein-coding, and metabolism. Advancements in “omics” technologies have provided valuable tools to unravel the mechanisms involved in the pathogenesis of this disease. In this study, we performed shotgun mass spectrometry in peripheral blood mononuclear cells (PBMC) from septic patients (N=24) and healthy controls (N=9) and combined these results with two public microarray leukocytes datasets. Through combination of transcriptome and proteome profiling, we identified 170 co‐differentially expressed genes/proteins. Among these, 122 genes/proteins displayed the same expression trend. Ingenuity Pathway Analysis revealed pathways related to lymphocyte functions with decreased status, and defense processes that were predicted to be strongly increased. Protein-protein interaction network analyses revealed two densely connected regions, which mainly included down‐regulated genes/proteins that were related to the transcription of RNA, translation of proteins, and mitochondrial translation. Additionally, we identified one module comprising of up‐regulated genes/proteins, which were mainly related to low-density neutrophils (LDNs). LDNs were reported in sepsis and in COVID-19. Changes in gene expression level were validated using quantitative real-time PCR in PBMCs from patients with sepsis. To further support that the source of the upregulated module of genes/proteins found in our results were derived from LDNs, we identified an increase of this population by flow cytometry in PBMC samples obtained from the same cohort of septic patients included in the proteomic analysis. This study provides new insights into a reprioritization of biological functions in response to sepsis that involved a transcriptional and translational shutdown of genes/proteins, with exception of a set of genes/proteins related to LDNs and host‐defense system.

Epigenetic Regulation in Sepsis, Role in Pathophysiology and Therapeutic Perspective

Sepsis is characterized by an initial hyperinflammatory response, with intense cell activation and cytokine storm. In parallel, a prolonged compensatory anti-inflammatory response, known as immunological tolerance, can lead to immunosuppression. Clinically, this condition is associated with multiple organ failure, resulting in the patient's death. The mechanisms underlying the pathophysiology of sepsis are not yet fully understood, but evidence is strong showing that epigenetic changes, including DNA methylation and post-translational modifications of histones, modulate the inflammatory response of sepsis. During the onset of infection, host cells undergo epigenetic changes that favor pathogen survival. Besides, epigenetic changes in essential genes also orchestrate the patient's inflammatory response. In this review, we gathered studies on sepsis and epigenetics to show the central role of epigenetic mechanisms in various aspects of the pathogenesis of sepsis and the potential of epigenetic interventions for its treatment.

Lipid metabolism impairment in patients with sepsis secondary to hospital acquired pneumonia, a proteomic analysis

Background

Sepsis is a dysregulated host response to infection and a major cause of death worldwide. Respiratory tract infections account for most sepsis cases and depending on the place of acquisition, i.e., community or hospital acquired infection, differ in etiology, antimicrobial resistance and outcomes. Accordingly, the host response may be different in septic patients secondary to community-acquired pneumonia and hospital acquired pneumonia (HAP). Proteomic analysis is a useful approach to evaluate broad alterations in biological pathways that take place during sepsis. Here we evaluated plasma proteome changes in sepsis secondary to HAP.

Methods

Plasma samples were obtained from patients (n = 27) at admission and after 7 days of follow-up, and were analyzed according to the patients’ outcomes. The patients’ proteome profiles were compared with healthy volunteers (n = 23). Pooled plasma samples were labeled with isobaric tag for relative and absolute quantitationand analyzed by LC–MS/MS. We used bioinformatics tools to find altered functions and pathways. Results were validated using biochemical estimations and ELISA tests.

Results

We identified 159 altered proteins in septic patients; most of them were common when comparing patients’ outcomes, both at admission and after 7 days. The top altered biological processes were acute inflammatory response, response to wounding, blood coagulation and homeostasis. Lipid metabolism emerged as the main altered function in patients, with HDL as a central node in the network analysis, interacting with downregulated proteins, such as APOA4, APOB, APOC1, APOL1, SAA4 and PON1. Validation tests showed reduced plasma levels of total cholesterol, HDL-C, LDL-C, non-HDL cholesterol, apolipoproteins ApoA1 and ApoB100, and Paraoxonase 1 in HAP patients.

Conclusion

Proteomic analysis pointed to impairment of lipid metabolism as a major change in septic patients secondary to HAP, which was further validated by the reduced levels of cholesterol moieties and apolipoproteins in plasma. Our results stress the involvement of lipids in the pathogenesis of sepsis, which is in accordance with previous reports supporting the role of lipid moieties in pathogen toxin clearance and in modulating inflammatory responses.

Electronic supplementary material

The online version of this article (10.1186/s12014-019-9252-2) contains supplementary material, which is available to authorized users.

B-cell subsets imbalance and reduced expression of CD40 in ataxia-telangiectasia patients

BACKGROUND

Ataxia-telangiectasia (AT) is a well-known primary immunodeficiency with recurrent sinopulmonary infections and variable abnormalities in both the humoral and cellular immune system. Dysfunctions in immunoglobulin production, reduced number of B cells, and B-cell receptor excision circles copies have been reported. We aimed to understand the immunological mechanisms involving the humoral compartment in AT patients by analysing peripheral blood B cells subsets, B-T lymphocyte cooperation through the expression of CD40 and CD40 ligand (CD40L), and cytokines involved in class-switch recombination production.

METHODS

We compared the proportion of B-cell subsets, the expression of CD40/CD40L, and the plasma levels of IL-6 and IFN-γ of 18 AT patients and 15 healthy age-sex-matched controls using flow cytometry.

RESULTS

We found that some steps in peripheral B cell development were altered in AT with a pronounced reduction of cell-surface CD40 expression. The proportions of transitional and naïve-mature B cells were reduced, whereas CD21-low, natural effector memory, IgM-only memory, and IgG atypical memory B cells were present in a higher proportion.

CONCLUSIONS

These findings revealed a disturbed B-cell homeostasis with unconventional maturation of B lymphocyte memory cells, which can explain the consequent impairment of humoral immunity.

Proteomic study revealed cellular assembly and lipid metabolism dysregulation in sepsis secondary to community-acquired pneumonia

Sepsis is a life-threatening disorder characterized by organ dysfunction and a major cause of mortality worldwide. The major challenge in studying sepsis is its diversity in such factors as age, source of infection and etiology. Recently, genomic and proteomic approaches have improved our understanding of its complex pathogenesis. In the present study, we use quantitative proteomics to evaluate the host proteome response in septic patients secondary to community-acquired pneumonia (CAP). Samples obtained at admission and after 7 days of follow-up were analyzed according to the outcomes of septic patients. The patients' proteome profiles were compared with age- and gender-matched healthy volunteers. Bioinformatic analyses of differentially expressed proteins showed alteration in the cytoskeleton, cellular assembly, movement, lipid metabolism and immune responses in septic patients. Actin and gelsolin changes were assessed in mononuclear cells using immunofluorescence, and a higher expression of gelsolin and depletion of actin were observed in survivor patients. Regarding lipid metabolism, changes in cholesterol, HDL and apolipoproteins were confirmed using enzymatic colorimetric methods in plasma. Transcriptomic studies revealed a massive change in gene expression in sepsis. Our proteomic results stressed important changes in cellular structure and metabolism, which are possible targets for future interventions of sepsis.

Inflammasome gene profile is modulated in septic patients, with a greater magnitude in non-survivors

Inflammasome signalling induces the processing and secretion of interleukin (IL)-1β and IL-18 which, coupled with pyroptosis, activate further the inflammatory response. In the present study we evaluated the expression of genes involved in inflammasome signalling pathways in septic patients, their interaction networks and the predicted functions modulated in survivors and non-survivors. Twenty-seven patients with sepsis secondary to community-acquired pneumonia admitted to intensive care units from three general hospitals in São Paulo were included into the study. We performed a polymerase chain reaction (PCR) array encompassing 35 genes related to the nucleotide-binding oligomerization domain and leucine-rich repeat-containing (NLR)-inflammasome in peripheral blood mononuclear cells obtained at admission and after 7 days of follow-up. Eleven healthy volunteers were used as the reference group. Increased NLRC4 and NLRP3 and decreased nucleotide-binding oligomerization domain (NOD1), and NLRP1 expression was observed in septic patients compared to healthy individuals; the IL-1β and IL-18 expression levels were also high in the patients. The gene expression changes followed the same patterns in surviving and non-surviving patients, with higher magnitudes observed in non-survivors. Functional analyses revealed, however, that activation and inhibition intensity for representing functions were different in survivors and non-survivors, as for production of reactive oxygen species, synthesis of nitric oxide and for the control of bacterial infections. Our results showed that the genes involved in the activation of the NLR-inflammasome cascades were altered substantially in septic patients, with a higher number of altered genes and a higher intensity in the disturbance of gene expression found among patients dying of sepsis.

CD163 and CD206 expression does not correlate with tolerance and cytokine production in LPS-tolerant human monocytes

BACKGROUND

Lipopolysaccharide (LPS)-tolerant monocytes produce small amounts of inflammatory cytokines, which is one of the characteristics of the alternative activated macrophages (AAM). These cells exhibited an increased expression of CD206 and CD163. Given the functional similarities of AAMs with the modulation of monocytes' functions observed during sepsis and LPS-tolerance, we evaluated whether the inhibition of inflammatory cytokine production by LPS-tolerant monocytes is associated with the phenotype of cells expressing CD206 and CD163.

METHODS

We investigated whether tolerant human monocytes would modulate their expression of CD206 and CD163, markers of alternative activation, and whether the level of their expression would be related to cytokines detection. Tolerance to LPS was induced in peripheral blood mononuclear cell by pre-incubating the cells with increasing concentrations of LPS. The expression of CD206 and CD163 and intracellular TNF-α and IL-6 was determined 24 h after LPS challenge by flow cytometry.

RESULTS

No differences in CD163 expression were observed between tolerant and non-tolerant cells, while the expression of CD206, which was decreased following LPS stimulation in non-tolerized cells, was further reduced in tolerant cells. Decreased production of inflammatory cytokines was observed in the tolerized cells, regardless of the expression of CD163 and CD206, with the exception of IL-6 in CD206+ monocytes, which was similarly expressed in both tolerized and non-tolerized cells.

CONCLUSIONS

The effect of LPS in the expression of CD163 and CD206 on monocytes is not reverted in LPS tolerant cells, and the inhibition of inflammatory cytokines in tolerant cells is not related with modulation of these receptors. © 2016 International Clinical Cytometry Society.

Gene expression profiling of mononuclear cells from patients with sepsis secondary to community-acquired pneumonia

Mechanisms governing the inflammatory response during sepsis involve crosstalk between diverse signaling pathways, but current knowledge provides an incomplete picture of the syndrome. Microarray-based expression profiling is a powerful approach for the investigation of complex clinical conditions such as sepsis. In this study, we investigated whole-genome expression profiles in mononuclear cells from septic patients admitted in intensive care units with community-acquired pneumonia. Blood samples were collected at the time of sepsis diagnosis and seven days later since we aimed to evaluate the role of biological processes or genes possibly involved in patient recovery. Here we provide a detailed description of the study design, including clinical information, experimental methods and procedures regarding data analysis. Metadata corresponding to microarray results deposited in the database Gene Expression Omnibus (GEO) under the accession number GSE48080 are also described in this report. Our dataset allows the identification of genes possibly associated with host defense to infection as well as gene expression patterns associated with patient outcome.

Evaluation of Toll-like, chemokine, and integrin receptors on monocytes and neutrophils from peripheral blood of septic patients and their correlation with clinical outcomes

Recognition of pathogens is performed by specific receptors in cells of the innate immune system, which may undergo modulation during the continuum of clinical manifestations of sepsis. Monocytes and neutrophils play a key role in host defense by sensing and destroying microorganisms. This study aimed to evaluate the expression of CD14 receptors on monocytes; CD66b and CXCR2 receptors on neutrophils; and TLR2, TLR4, TLR5, TLR9, and CD11b receptors on both cell types of septic patients. Seventy-seven septic patients (SP) and 40 healthy volunteers (HV) were included in the study, and blood samples were collected on day zero (D0) and after 7 days of therapy (D7). Evaluation of the cellular receptors was carried out by flow cytometry. Expression of CD14 on monocytes and of CD11b and CXCR2 on neutrophils from SP was lower than that from HV. Conversely, expression of TLR5 on monocytes and neutrophils was higher in SP compared with HV. Expression of TLR2 on the surface of neutrophils and that of TLR5 on monocytes and neutrophils of SP was lower at D7 than at D0. In addition, SP who survived showed reduced expression of TLR2 and TLR4 on the surface of neutrophils at D7 compared to D0. Expression of CXCR2 for surviving patients was higher at follow-up compared to baseline. We conclude that expression of recognition and cell signaling receptors is differentially regulated between SP and HV depending on the receptor being evaluated.

Increased percentages of T helper cells producing IL-17 and monocytes expressing markers of alternative activation in patients with sepsis

Background

A shift from Th1 to Th2 as well as an increase in Treg CD4+T cell subsets has been reported in septic patients (SP). Furthermore, these patients display modulation of monocyte function, with reduced production of pro-inflammatory cytokines upon LPS stimulus, which resembles the phenotype of alternatively activated macrophages. In this study, we evaluated the percentages of T cells differentiated into Th1, Th17 and Treg subsets, as well as the percentage of monocytes expressing markers of alternatively activated monocytes/macrophages (AAM) in SP.

Methodology/Principal Findings

Peripheral blood mononuclear cells (PBMC) were obtained from 32 healthy volunteers (HV) and from SP at admission (D0, n = 67) and after 7 days of therapy (D7, n = 33). Th1 and Th17 (CD3+CD8−) lymphocytes were identified by the intracellular detection of IFN-γ and IL-17, respectively, spontaneously and after PMA/Io stimulation, and Treg cells were identified by Foxp3+CD127- expression. Monocytes were evaluated for CD206 and CD163 expression. Absolute numbers of CD4+T lymphocytes were measured in whole blood samples by flow cytometry. The Mann-Whitney or Wilcoxon test was applied, as appropriate. The percentage of Th1 cells was lower in SP than in HV at admission after PMA/Io stimulation, whereas the percentage of Th17 cells was higher. In patients’ follow-up samples, a higher percentage of Th1 cells and a lower percentage of Th17 cells were observed on D7 compared with the D0 samples. Treg cells remained unchanged. Septic patients showed a markedly increased proportion of monocytes expressing CD163 and CD206.

Conclusions/Significance

Upon in vitro stimulus, the percentage of T helper lymphocytes producing IL-17 was higher in SP than in HV at admission, and the percentage producing IFN-γ was lower, a pattern that was reversed during follow-up. The increased expression of CD163 and CD206 indicates that monocytes may acquire the AAM phenotype during sepsis.

Human monocytes tolerant to LPS retain the ability to phagocytose bacteria and generate reactive oxygen species

Tolerance to lipopolysaccharide (LPS) occurs when animals or cells exposed to LPS become hyporesponsive to a subsequent challenge with LPS. This mechanism is believed to be involved in the down-regulation of cellular responses observed in septic patients. The aim of this investigation was to evaluate LPS-induced monocyte tolerance of healthy volunteers using whole blood. The detection of intracellular IL-6, bacterial phagocytosis and reactive oxygen species (ROS) was determined by flow cytometry, using anti-IL-6-PE, heat-killed Staphylococcus aureus stained with propidium iodide and 2',7'-dichlorofluorescein diacetate, respectively. Monocytes were gated in whole blood by combining FSC and SSC parameters and CD14-positive staining. The exposure to increasing LPS concentrations resulted in lower intracellular concentration of IL-6 in monocytes after challenge. A similar effect was observed with challenge with MALP-2 (a Toll-like receptor (TLR)2/6 agonist) and killed Pseudomonas aeruginosa and S. aureus, but not with flagellin (a TLR5 agonist). LPS conditioning with 15 ng/mL resulted in a 40% reduction of IL-6 in monocytes. In contrast, phagocytosis of P. aeruginosa and S. aureus and induced ROS generation were preserved or increased in tolerant cells. The phenomenon of tolerance involves a complex regulation in which the production of IL-6 was diminished, whereas the bacterial phagocytosis and production of ROS was preserved. Decreased production of proinflammatory cytokines and preserved or increased production of ROS may be an adaptation to control the deleterious effects of inflammation while preserving antimicrobial activity.

Lipopolysaccharide-induced expression of cell surface receptors and cell activation of neutrophils and monocytes in whole human blood

Lipopolysaccharide (LPS) activates neutrophils and monocytes, inducing a wide array of biological activities. LPS rough (R) and smooth (S) forms signal through Toll-like receptor 4 (TLR4), but differ in their requirement for CD14. Since the R-form LPS can interact with TLR4 independent of CD14 and the differential expression of CD14 on neutrophils and monocytes, we used the S-form LPS from Salmonella abortus equi and the R-form LPS from Salmonella minnesota mutants to evaluate LPS-induced activation of human neutrophils and monocytes in whole blood from healthy volunteers. Expression of cell surface receptors and reactive oxygen species (ROS) and nitric oxide (NO) generation were measured by flow cytometry in whole blood monocytes and neutrophils. The oxidative burst was quantified by measuring the oxidation of 2',7'-dichlorofluorescein diacetate and the NO production was quantified by measuring the oxidation of 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate. A small increase of TLR4 expression by monocytes was observed after 6 h of LPS stimulation. Monocyte CD14 modulation by LPS was biphasic, with an initial 30% increase followed by a 40% decrease in expression after 6 h of incubation. Expression of CD11b was rapidly up-regulated, doubling after 5 min on monocytes, while down-regulation of CXCR2 was observed on neutrophils, reaching a 50% reduction after 6 h. LPS induced low production of ROS and NO. This study shows a complex LPS-induced cell surface receptor modulation on human monocytes and neutrophils, with up- and down-regulation depending on the receptor. R- and S-form LPS activate human neutrophils similarly, despite the low CD14 expression, if the stimulation occurs in whole blood.

Effect of pentoxifylline on lung inflammation and gas exchange in a sepsis-induced acute lung injury model

Experimental models of sepsis-induced pulmonary alterations are important for the study of pathogenesis and for potential intervention therapies. The objective of the present study was to characterize lung dysfunction (low PaO2 and high PaCO2, and increased cellular infiltration, protein extravasation, and malondialdehyde (MDA) production assessed in bronchoalveolar lavage) in a sepsis model consisting of intraperitoneal (ip) injection of Escherichia coli and the protective effects of pentoxifylline (PTX). Male Wistar rats (weighing between 270 and 350 g) were injected ip with 10(7) or 10(9) CFU/100 g body weight or saline and samples were collected 2, 6, 12, and 24 h later (N = 5 each group). PaO2, PaCO2 and pH were measured in blood, and cellular influx, protein extravasation and MDA concentration were measured in bronchoalveolar lavage. In a second set of experiments either PTX or saline was administered 1 h prior to E. coli ip injection (N = 5 each group) and the animals were observed for 6 h. Injection of 10(7) or 10(9) CFU/100 g body weight of E. coli induced acidosis, hypoxemia, and hypercapnia. An increased (P < 0.05) cell influx was observed in bronchoalveolar lavage, with a predominance of neutrophils. Total protein and MDA concentrations were also higher (P < 0.05) in the septic groups compared to control. A higher tumor necrosis factor-alpha (P < 0.05) concentration was also found in these animals. Changes in all parameters were more pronounced with the higher bacterial inoculum. PTX administered prior to sepsis reduced (P < 0.05) most functional alterations. These data show that an E. coli ip inoculum is a good model for the induction of lung dysfunction in sepsis, and suitable for studies of therapeutic interventions.

Bacterial recognition and induced cell activation in sepsis

The pathogenesis of sepsis involves complex interaction between the host and the infecting microorganism. Recognition and processing of microorganism antigens are essential functions of the cells of innate immune systems, and will ultimately, through the antigen presentation to the cells of adaptive immunity and the synthesis and secretions of mediators, such as cytokines, drive a coordinated immune response. Neutrophils and monocytes will therefore function as sensing and effectors cells. Fundamental in this process is the ability to discriminate self from non-self molecules. Of major interest in sepsis is that the protective and damaging host responses are part of the same process, that is, the inflammatory response that controls the infection process also underscores many of the pathophysiological events of sepsis. Moreover, this is a dynamic process according to the continuum of sepsis and its complications; up and down regulation of cellular activities may be differently regulated in different tissues, different cells and even in different functions of the same cell. This review will focus on microorganism recognition and signalization in sepsis, with emphasis on the neutrophils and monocytes adaptation during the ongoing disease.

TLR2, TLR4, CD14, CD11B, AND CD11C EXPRESSIONS ON MONOCYTES SURFACE AND CYTOKINE PRODUCTION IN PATIENTS WITH SEPSIS, SEVERE SEPSIS, AND SEPTIC SHOCK

Bacterial recognition and induced cellular activation are fundamental for the host control of infection, yet the limit between protective and harmful response is still inexact. Forty-one patients were enrolled in this study: 14 with sepsis, 12 with severe sepsis, and 15 with septic shock. Seventeen healthy volunteers (HV) were included as control. The expression of TLR2, TLR4, CD14, CD11b, and CD11c was analyzed on monocytes surface in whole blood. sCD14 was measured in serum, and TNF-alpha, IL-6, and IL-10 cytokine levels were measured in PBMC supernatants after LPS, IL-1beta, and TNF-alpha stimuli by ELISA. An increase in sCD14 and a decreased mCD14 were found in patients as compared with HV (P < 0.001). However, no differences in the expression of TLR2, TLR4, and CD11c were found among the groups. A trend toward differential expression of CD11b was observed, with higher values found in patients with sepsis as compared with HV. A negative regulation of the inflammatory cytokine production was observed in patients with severe sepsis and shock septic in relation to sepsis and HV, regardless of the stimulus. No significant difference in IL-10 production was found among the groups. In this study, we show that the inflammatory response is associated with the continuum of clinical manifestations of sepsis, with a strong inflammatory response in the early phase (sepsis) and a refractory picture in the late phases (severe sepsis and septic shock). Correlation between cell surface receptors and cytokine production after IL-1beta and TNF-alpha stimuli and the observation of a single and same standard response with the different stimulus suggest a pattern of immunology response that is not dependent only on the expression of the evaluated receptors and that is likely to have a regulation in the intracellular signaling pathways.

Leptospira interrogans activation of peripheral blood monocyte glycolipoprotein demonstrated in whole blood by the release of IL-6

Glycolipoprotein (GLP) from pathogenic serovars of Leptospira has been implicated in the pathogenesis of leptospirosis by its presence in tissues of experimental animals with leptospirosis, the inhibition of the Na,K-ATPase pump activity, and induced production of cytokines. The aims of the present study were to investigate the induction of IL-6 by GLP in peripheral blood mononuclear cells (PBMC) and to demonstrate monocyte stimulation at the cellular level in whole blood from healthy volunteers. PBMC were stimulated with increasing concentrations (5 to 2500 ng/ml) of GLP extracted from the pathogenic L. interrogans serovar Copenhageni, lipopolysaccharide (positive control) or medium (negative control), and supernatants were collected after 6, 20/24, and 48 h, and kept at -80 degrees C until use. Whole blood was diluted 1:1 in RPMI medium and cultivated for 6 h, with medium, GLP and lipopolysaccharide as described above. Monensin was added after the first hour of culture. Supernatant cytokine levels from PBMC were measured by ELISA and intracellular IL-6 was detected in monocytes in whole blood cultures by flow-cytometry. Monocytes were identified in whole blood on the basis of forward versus side scatter parameters and positive reactions with CD45 and CD14 antibodies. GLP ( > or = 50 ng/ml)-induced IL-6 levels in supernatants were detected after 6-h incubation, reaching a peak after 20/24 h. The percentage of monocytes staining for IL-6 increased with increasing GLP concentration. Thus, our findings show a GLP-induced cellular activation by demonstrating the ability of GLP to induce IL-6 and the occurrence of monocyte activation in whole blood at the cellular level.

An imbalance of naive and memory/effector subsets and altered expression of CD38 on T lymphocytes in two girls with hyper-IgM syndrome

In this report we evaluated CD4(+) T, CD8(+) T and natural killer (NK) cell counts, the levels of naive/memory subsets within the CD4(+) T lymphocyte population, expression of CD38 on T lymphocytes, and CD4(+) and CD8(+) T cell cytokine production in two girls with hyper-IgM (HIM) syndrome. Both girls developed recurrent infections early in infancy, presenting a wide spectrum of clinical manifestations, with a strikingly different disease severity between them. CD4(+) T cell counts were low in both children (patient 1: 214 cells/mm(3) and patient 2: 392 cells/mm(3)), and the CD4/CD8 T cell ratio was 0.4 for patient 1, the patient with the more severe disease, and 1.4 for patient 2. NK cell numbers were low in patient 1 (60 cells/mm(3)) and borderline (286 cells/mm(3)) with regard to normal levels in patient 2. An imbalance of naive and memory/effector cell subsets was found in both girls, with the percentage of CD45RA(+) 27(+) (naive) CD4(+) T lymphocytes being 5.8 and 12.4 for patients 1 and 2, respectively. Expression of CD38 on the surface of T lymphocytes was low in patient 1. Detection of intracellular interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha in CD4(+) and CD8(+) T lymphocytes upon PMA-Io stimulus was preserved in both children. In conclusion, we found low numbers of CD4(+) T lymphocytes and a dramatic redistribution of naive and memory/effector CD4(+) T lymphocytes in two girls with non-X-linked HIM syndrome. Furthermore, we found low expression of CD38 on T lymphocytes and low numbers of NK cells in the patient with the more severe disease, indicating a possible role for these cells in the pathogenesis of this immunodeficiency.

Induction of interleukin-10 by HIV antigens in peripheral mononuclear cells of health care workers after occupational exposure to HIV-1-positive blood

Evaluation of HIV-induced IL-2 production by peripheral blood mononuclear cells (PBMC) and HIV-specific T helper and cytotoxic T lymphocyte (CTL) responses in health care workers (HCW) occupationally exposed to HIV reveals a high rate of response to HIV among non-seroconverters. IL-10 is also known to interfere with HIV infection in vitro. To evaluate the induction of IL-10 by HIV antigens in HCW occupationally exposed to HIV, 18 HCW with percutaneous injury were enrolled in this study, 9 of them exposed to HIV-contaminated blood, and 9 exposed to HIV-negative blood. PBMC were incubated on plates coated with HIV-1 antigens, and IL-10 was measured in supernatants by ELISA. Five of nine HCW exposed to HIV-contaminated blood presented HIV-induced IL-10. Two of nine HCW exposed to HIV-negative source patients also had detectable levels of HIV-induced IL-10, one of them in the sample obtained on the day of accidental exposure. There was a relationship between the type of device involved in injury and IL-10 production. Individuals exposed to hollow needles or scalpels presented HIV-induced IL-10, whereas those exposed to solid needles and to digital puncture did not, suggesting a relationship between infectious load and IL-10. Although occupational exposure to HIV leads to a low rate of seroconversion, these individuals can develop an antigen-specific immune response characterized in our study by induction of IL-10 in PBMC in vitro.

Peripheral blood mononuclear cell activation induced by Leptospira interrogans glycolipoprotein

Leptospira interrogans glycolipoprotein (GLP) has been implicated in pathological and functional derangement seen in leptospirosis. The goal of this study was to evaluate GLP's ability to induce cellular activation, as assessed by cytokine production and expression of surface activation markers. GLP extracted from either pathogenic L. interrogans serovar Copenhageni or nonpathogenic Leptospira biflexa serovar Patoc (GLPp) was used to stimulate peripheral blood mononuclear cell cultures from healthy donors. Supernatant cytokine levels were measured by enzyme-linked immunosorbent assay. Expression of CD69 and HLA-DR on lymphocytes and monocytes, as well as lipopolysaccharide (LPS) binding, were measured by flow cytometry. At 6 h of incubation, GLP induced a significant rise in tumor necrosis factor alpha levels, which dropped progressively until 72 h of incubation. Interleukin-10 peak levels were obtained at between 24 and 48 h, with sustained levels until 72 h of incubation. The response magnitude was proportional to the GLP dose. CD69 expression on T lymphocytes and monocytes increased significantly, as did HLA-DR expression on monocytes. GLPp induced no CD69 or HLA-DR expression. GLP did not block biotinylated LPS binding to monocytes, suggesting that different pathways are used to induce cell activation. In conclusion, GLP induces cellular activation and may play a major role in the pathogenesis of leptospirosis.