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Guillaume Monneret

Publications and source records attributed to Guillaume Monneret.

At least 19 recordsLinked to original sources
PubMed2006

Human CD4+CD25+ regulatory T lymphocytes inhibit lipopolysaccharide-induced monocyte survival through a Fas/Fas ligand-dependent mechanism.

Although it is known that septic shock induces immunosuppression, the mechanism for this phenomenon is not well understood. Monocytes play a central role in septic shock pathophysiology, which is also characterized by an increased proportion of natural regulatory T (Treg) cells. We therefore investigated whether Treg could be involved in the decreased monocyte expression of CD14 and HLA-DR observed during septic shock. We demonstrated that human Treg inhibit LPS-induced retention of monocyte CD14. Because loss of CD14 is a hallmark of monocyte apoptosis, this suggests that Treg inhibit monocyte survival. This effect was largely mediated through the release of a soluble mediator that was not identical with either IL-10 or IL-4. The Fas/FasL pathway participated in the effect as it was blocked by anti-FasL Abs and reproduced by Fas agonist and recombinant soluble FasL. Furthermore, expression of FasL was much higher on Treg than on their CD25(-) counterparts. Collectively, these results indicate that Treg act on monocytes by inhibiting their LPS-induced survival through a proapoptotic mechanism involving the Fas/FasL pathway. This may be an important mechanism for septic shock-induced immunosuppression and may offer new perspectives for the treatment of this deadly disease.

CD4 Antigens↗
PubMed2006

Comparative inflammatory properties of staphylococcal superantigenic enterotoxins SEA and SEG: implications for septic shock.

The severity of Staphylococcus aureus sepsis is positively associated with staphylococcal enterotoxin A (SEA) and negatively associated with the enterotoxin gene cluster (egc), which encodes five staphylococcal enterotoxins. We postulated that the variable, clinical severity of S. aureus sepsis might be a result of differences in the inflammatory properties of staphylococcal superantigens. We therefore compared the inflammatory properties of SEA with those of staphylococcal entérotoxin G (SEG), a member of the five egc superantigens. We found that SEA and SEG had similar superantigenic properties, as they induced CD69 expression on T lymphocytes and selective expansion of Vbeta subpopulations. Contrary to SEG, however, SEA induced a strong proinflammatory/Th1 response, including TNF-alpha and MIP-1alpha production. These results suggest that the association of SEA with the severity of S. aureus septic shock, characterized by a deleterious, inflammatory cascade, may be explained partly by the specific proinflammatory properties of this superantigen.

Antigens, CD↗
PubMed2006

Persisting low monocyte human leukocyte antigen-DR expression predicts mortality in septic shock.

OBJECTIVE: The immediate overwhelming release of inflammatory mediators in septic shock is rapidly followed by strong anti-inflammatory responses inducing a state of immunosuppression. The patients who survive the initial hyper-inflammatory step of septic shock but subsequently die may be those who do not recover from immunosuppression. We assessed whether a low monocyte human leukocyte antigen-DR (mHLA-DR) expression, proposed as a marker of immunosuppression, is an independent predictor of mortality in patients who survived the initial 48 h of septic shock. DESIGN AND SETTING: Prospective observational study performed in two adult intensive care units at a university hospital. PATIENTS: 93 consecutive patients with septic shock. MEASUREMENTS AND RESULTS: At days 1-2, mHLA-DR values (determined by flow cytometry) were not significantly different between survivors and non-survivors. A sharp difference became highly significant at days 3-4 when survivors had increased their values, while non-survivors had not (43% vs. 18%, percentage of HLA-DR positive monocyte, p < 0.001). Multivariate logistic regression analysis revealed that low mHLA-DR (< 30%) at days 3-4 remained independently associated with mortality after adjustment for usual clinical confounders, adjusted odds ratio (CI): 6.48 (95% CI: 1.62-25.93). CONCLUSION: The present preliminary results show that mHLA-DR is an independent predictor of mortality in septic shock patients. Being a marker of immune failure, low mHLA-DR may provide a rationale for initiating therapy to reverse immunosuppression. After validation of the current results in multicenter studies, mHLA-DR may help to stratify patients when designing a mediator-directed therapy in a time-dependent manner.

Aged↗
PubMed2006

Systemic transcriptional analysis in survivor and non-survivor septic shock patients: a preliminary study.

The second phase of septic shock is characterized by an anti-inflammatory state and patients rapidly develop features consistent with immunosuppression. The mechanisms sustaining this disease step are far from being well understood. The objective of the present study was to perform a genome-wide survey of mRNA expression in septic shock patients in order to investigate the bases of sepsis-induced immunoparalysis. We used Affymetrix HG-U133A oligonucleotide arrays to compare systemic gene expression patterns of survivors and non-survivors after the first 24 h of the syndrome (n = 38 patients). Supervised analysis identified a set of 28 genes efficiently discriminating non-survivors from survivors with a sensitivity of 100% and a specificity of 86%. The microarray findings were confirmed by qRT-PCR and the ability of the selected probe sets to function as a classifier of outcome was verified with an independent set of additional microarray analyses. Noteworthy, of gene overexpressed in survivors, many are known to participate in innate immunity (cytokine, chemokine receptor, effectors of the Toll-receptor pathways). It supports the hypothesis that restoration of inflammatory/immune functions is a key step for survival after septic shock. The consistency of our results into the context of sepsis-induced immunoparalysis tends to indicate that blood transcriptional profiling is a valuable approach not only for patients stratification but also to identity new genes possibly involved in sepsis pathophysiology.

Aged↗
PubMed2006

The expression of TCR-gamma delta/CD3 complex in neoplastic gamma delta T-cell.

We describe that the neoplastic gammadelta T-cells from patients with hepatosplenic gammadelta T-cell lymphoma have a lower expression of TCR-gammadelta/CD3 complex compared to their normal or reactive counterparts. Interestingly, with the use of an appropriate antibody association, this feature is easily and rapidly observed on flow cytometry graphics.

CD3 Complex↗
PubMed2005

Monitoring temporary immunodepression by flow cytometric measurement of monocytic HLA-DR expression: a multicenter standardized study.

BACKGROUND: Single-center trials have shown that monocytic HLA-DR is a good marker for monitoring the severity of temporary immunodepression after trauma, major surgery, or sepsis. A new test for measuring monocytic HLA-DR is now available. METHODS: We evaluated a new test reagent set for monocytic HLA-DR expression (BD Quantibritetrade mark HLA-DR/Monocyte reagent; Becton Dickinson) in single-laboratory and interlaboratory experiments, assessing preanalytical handling, lyse-no-wash (LNW) vs lyse-wash (LW) values, reference values, and the effect of use of different flow cytometers and different instrument settings on test variance. RESULTS: For preanalytical handling, EDTA anticoagulation, storage on ice as soon as possible, and staining within 4 h after blood collection gave results comparable to values obtained for samples analyzed immediately after collection (mean increase of approximately 4% in monocytic HLA-DR). Comparison of LNW and LW revealed slightly higher results for LNW ( approximately 18% higher for LNW compared with LW; r = 0.982). Comparison of different flow cytometers and instrument settings gave CVs <4%, demonstrating the independence of the test from these variables and suggesting that this method qualifies as a standardized test. CV values from the interlaboratory comparison ranged from 15% (blood sample unprocessed before transport) to 25% (stained and fixed before transport). CONCLUSIONS: For the BD Quantibrite HLA-DR/Monocyte test, preanalytical handling is standardized. Single-laboratory results demonstrated the independence of this test from flow cytometer and instrument settings. Interlaboratory results showed greater variance than single-laboratory values. This interlaboratory variance was partly attributable to the influence of transport and can be reduced by optimization of transport conditions.

Flow Cytometry↗
PubMed2005

The basophil activation test by flow cytometry: recent developments in clinical studies, standardization and emerging perspectives.

The diagnosis of immediate allergy is mainly based upon an evocative clinical history, positive skin tests (gold standard) and, if available, detection of specific IgE. In some complicated cases, functional in vitro tests are necessary. The general concept of those tests is to mimic in vitro the contact between allergens and circulating basophils. The first approach to basophil functional responses was the histamine release test but this has remained controversial due to insufficient sensitivity and specificity. During recent years an increasing number of studies have demonstrated that flow cytometry is a reliable tool for monitoring basophil activation upon allergen challenge by detecting surface expression of degranulation/activation markers (CD63 or CD203c). This article reviews the recent improvements to the basophil activation test made possible by flow cytometry, focusing on the use of anti-CRTH2/DP2 antibodies for basophil recognition. On the basis of a new triple staining protocol, the basophil activation test has become a standardized tool for in vitro diagnosis of immediate allergy. It is also suitable for pharmacological studies on non-purified human basophils. Multicenter studies are now required for its clinical assessment in large patient populations and to define the cut-off values for clinical decision-making.

Journal Article↗
PubMed2005

FcgammaRIIIb and complement component C7 codeficiency in a patient with recurrence of fulminant meningococcal septic shock.

Individuals with deficiencies of the late components of complement exhibit a susceptibility to the recurrence of meningococcal disease with a usually mild clinical presentation. We report the recurrence of fulminant meningococcal disease in a complement component C7-deficient patient. We found a total deficiency of FcgammaRIIIb on neutrophils, which could partially explain the unusually severe clinical presentation.

Adolescent↗
PubMed2005

Longitudinal study of cytokine and immune transcription factor mRNA expression in septic shock.

Success in treating severe sepsis will require relevant tools to monitor the patient immunoinflammatory status. This study aimed to investigate the feasibility of measuring a panel of immunological mediator mRNAs in whole blood and to study their prognostic values in septic shock patients. At the onset of shock, compared to healthy volunteers, mRNA levels in septic shock patients were increased for IL-10, IL-1beta, and high mobility group B1 (HMGB1) and decreased for transforming growth factor beta 1, the Th1, and Th2 transcription factors, T-bet and GATA-3, respectively. Single parameter analysis highlighted an increased expression of IL-10 and HMGB1 mRNA in nonsurvivors and a significant rise over time of GATA3 in survivors. Combining the expression levels of four genes, hierarchical cluster analysis showed that up to 95% of the patients with a similar outcome displayed transcriptional similarities. These results illustrate both the potential of whole blood mRNA quantification assays and the interest of a multiparametric strategy to better stratify septic patients.

Aged↗
PubMed2005

Messenger RNA expression of major histocompatibility complex class II genes in whole blood from septic shock patients.

OBJECTIVE: The decreased expression of human leukocyte antigen (HLA)-DR on monocytes is proposed as a major feature of sepsis-induced immunodepression. The objective of the present study was to investigate, in whole blood from septic shock patients, the messenger RNA (mRNA) expression of a gene panel, which is essential to ensure major histocompatibility complex class II protein structure, transport, and peptide loading. DESIGN: The authors conducted a cohort study. SETTING: This study was conducted in intensive care units at a university hospital. SUBJECTS: The study included septic shock patients (n = 41) and healthy volunteers (n = 15). MEASUREMENTS AND MAIN RESULTS: Using quantitative reverse transcriptase-polymerase chain reaction, we found that the highly polymorphic HLA-DRB1 and nonpolymorphic-DRA mRNA levels were significantly decreased in whole blood from patients with septic shock compared with healthy volunteer both on days 1-3 and 4-10 after the onset of shock. This profile was also observed for genes encoding the invariant chain, the transcription factor class II transactivator (CIITA), and the enzymes involved in the peptide loading cathepsin S, HLA-DMA, and -DMB. The monocyte surface expression of HLA-DR measured by flow cytometry was significantly correlated with the whole-blood mRNA levels of HLA-DRB1 and -DRA and to a lesser extent with the other CIITA-regulated genes HLA-DMA and invariant chain. The correlation between HLA-DRB mRNA and cell-surface expression levels was also observed in a small subset of purified monocyte samples. Regarding the temporal relationship, a significant increase of whole-blood HLA-DRA, -DMA, -DMB, invariant chain, and CIITA mRNA level was observed in survivors (p = .001), whereas expressions remained low in nonsurvivors. CONCLUSIONS: A global transcriptional down regulation of a gene panel required for MHC II-restricted antigen presentation may occur in the course of septic shock. Our results suggest that the transcriptional resumption of CIITA-regulated genes might contribute to the recovery of membrane HLA-DR expression observed in survivors. These results obtained at the mRNA level support previous reports describing the loss of monocyte HLA-DR at the protein level and thus confirm the potential of measuring monocyte HLA-DR in septic patient followup.

Adult↗
PubMed2005

Both percentage of gammadelta T lymphocytes and CD3 expression are reduced during septic shock.

OBJECTIVE: The mechanisms involved during sepsis-induced immunosuppression are far from being extensively established. The objective of the present study was to investigate whether two characteristics of T cells were altered in this situation: the percentage of circulating gammadelta T lymphocytes and the level of CD3 expression on T lymphocytes. DESIGN: Observational study. SETTING: Adult intensive care units in a university hospital. PATIENTS: Patients with septic shock (n = 21) and healthy individuals (n = 21). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: In patients, we first observed the decreased percentage of gammadelta T lymphocytes in peripheral blood (1% [0.7-3.1], median [interquartile range]) in comparison with healthy individuals (3.5% [2.1-4.8]). Regarding CD3, we measured a highly significant decrease of its expression on both alphabeta and gammadelta T lymphocytes from patients (p < .005), whereas the CD3 mean fluorescence intensities ratio (gammadelta/alphabeta) was not affected: 2.2 [2.1-2.4] and 2.1 [1.9-2.3] in healthy individuals and septic patients, respectively. The magnitude in the decrease of CD3 expression was thus similar in alphabeta and gammadelta cells, suggesting a common down-regulation mechanism for both T-cell lineages. CONCLUSIONS: Combined with a reduced percentage of monocytes expressing human leukocyte antigen-DR, a reduced CD3 expression may be involved in the failure of antigen presentation depicted after septic shock, whereas the diminished percentage of circulating gammadelta T cells could be partly responsible for the elevated incidence of secondary infections. These two observations constitute additional pieces of the complex puzzle of sepsis-induced immunosuppression.

Aged↗
PubMed2004

Effects of prostaglandin D(2) and 5-lipoxygenase products on the expression of CD203c and CD11b by basophils.

Basophils are important in allergic diseases such as asthma because they produce a variety of inflammatory mediators. Activation of these cells with IgE and N-formyl-methionyl-leucyl-phenylalanine results in a variety of responses, including increased surface expression of CD203c and CD11b and release of histamine. Although considerable information is available on the effects of eicosanoids on neutrophils, eosinophils, and monocytes, less is known about their effects on basophils. In the present study, we examined the effects of various eicosanoids on the above basophil responses. Of the naturally occurring eicosanoids tested, prostaglandin D(2) (PGD(2); EC(50), 10 nM) was by far the most potent activator of CD203c expression, with other prostanoids having little effect. This response was mediated by the DP(2) receptor/chemoattractant receptor-homologous molecule expressed on Th2 cells because it was shared by the selective agonist 15R-methyl-PGD(2) (EC(50), 3 nM). The 5-lipoxygenase products leuko-triene B(4) and 5-oxo-6,8,11,14-eicosatetraenoic acid also stimulated CD203c expression but to a lesser extent than PGD(2), whereas leukotriene D(4) was inactive. Neither PGD(2) nor 5-oxo-6,8,11,14-eicosatetraenoic acid stimulated histamine release or CD63 expression on basophils. Both PGE(2) and the DP(1) receptor agonist BW245C [(4S)-(3-[(3R,S)-3-cyclohexyl-3-hydroxypropyl]-2,5-dioxo)-4-imidazolidineheptanoic acid] strongly inhibited DP(2) receptor-mediated CD203c expression. The DP(1) receptor antagonist BWA868C [3-[(2-cyclohexyl-2-hydroxyethyl)amino]-2,5-dioxo-1-(phenylmethyl)-4-imidazolidine-heptanoic acid] enhanced PGD(2)-induced CD203c expression, suggesting that interaction of PGD(2) with DP(1) receptors can limit activation of basophils by this prostaglandin. In conclusion, PGD(2) is the most potent inducer of basophil CD203c expression among eicosanoids and may be a key mediator in asthma and other allergic diseases. The balance between DP(1) and DP(2) receptors may be important in determining the magnitude of basophil responses to this prostaglandin.

Antigens, Surface↗
PubMed2004

5-oxo-6,8,11,14-eicosatetraenoic acid stimulates the release of the eosinophil survival factor granulocyte/macrophage colony-stimulating factor from monocytes.

Allergic diseases such as asthma are characterized by tissue eosinophilia induced by the combined effects of chemoattractants and cytokines. Lipid mediators are a major class of endogenous chemoattractants, among which 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE) is the most potent for human eosinophils. In this study, we investigated the effects of 5-oxo-ETE on eosinophil survival by flow cytometry. We found that this compound could promote eosinophil survival in the presence of small numbers of contaminating monocytes, but not in their absence. The conditioned medium from monocytes treated for 24 h with 5-oxo-ETE also strongly promoted eosinophil survival, whereas the medium from vehicle-treated monocytes had no effect. An antibody against the granulocyte/macrophage colony-stimulating factor (GM-CSF) completely blocked the response of eosinophils to the conditioned medium from 5-oxo-ETE-treated monocytes, whereas an antibody against interleukin-5 had no effect. Furthermore, 5-oxo-ETE stimulated the release of GM-CSF from cultured monocytes in amounts compatible with eosinophil survival activity, with a maximal effect being observed after 24 h. This effect was concentration-dependent and could be observed at concentrations in the picomolar range. 5-Oxo-ETE and leukotriene B(4) had similar effects on GM-CSF release at low concentrations, but 5-oxo-ETE induced a much stronger response at concentrations of 10 nm or higher. This is the first report that 5-oxo-ETE can induce the release of any cytokine, suggesting that it could be an important mediator in allergic and other inflammatory diseases due both to its chemoattractant properties and to its potent effects on the synthesis of the survival factor GM-CSF.

Arachidonic Acids↗
PubMed2004

The Th2 response as monitored by CRTH2 or CCR3 expression is severely decreased during septic shock.

The shift of T lymphocytes toward a Th2 profile during septic shock has been established on the basis of in vitro cytokine production. In the present study, the Th2 response was investigated at the level of cell surface marker expression (whole blood flow cytometry). In 58 patients with septic shock, we observed a reduced CRTH2 (chemoattractant receptor-homologous molecule expressed on Th2 cells) expression on Th2 lymphocytes and regulatory T cells in comparison with 39 healthy volunteers. Eosinophils, which constitutively express CRTH2 in healthy individuals, also exhibited low levels of CRTH2 in patients. In addition, eosinophil CCR3 expression (eotaxin receptor, type 2 chemokine) was strongly correlated with CRTH2, suggesting thus an extended modulation of Th2 related molecules. Importantly, the persistence over time of low levels of CRTH2 or CCR3 expression was found in nonsurvivors. We hypothesize that the restoration of CRTH2/CCR3 expression may be an indicator for optimal recovery after septic shock.

Aged↗
PubMed2004

The anti-inflammatory response dominates after septic shock: association of low monocyte HLA-DR expression and high interleukin-10 concentration.

The diminished expression of HLA-DR on monocytes has been proposed as a reliable marker of immunosuppression occuring during septic shock. The objective of the present observational study was to establish the time-dependent relation between plasma cytokines interleukin (IL)-10, transforming growth factor (TGF)-beta1, tumor necrosis factor (TNF)-alpha and monocyte HLA-DR expression in 38 adult patients with septic shock. All patients (mortality at 28 days: 42%, mean admission SAPS II score: 54) had decreased HLA-DR expression. This expression was significantly lower in non-survivors at all time points. All patients had elevated IL-10 concentrations, the highest values were found in non-survivors. IL-10 was the sole cytokine to significantly correlate with HLA-DR expression (r: -0.6, p<0.001). TNF and TGF values did not provide any prognostic information. TGF levels from septic patients were even found to be decreased in comparison with normal values which suggested that IL-10 is likely more important than TGF regarding the immunosuppressive properties of septic patients' plasma. This preliminary work showed that, at the systemic level, the anti-inflammatory response dominated after septic shock. Monocyte HLA-DR expression and IL-10 measurement deserve to be determined in parallel in a larger longitudinal study. They might constitute helpful indicators for staging patients and making a decision about whether to institute a therapy with molecules able of reversing sepsis-induced immunosuppression.

Aged↗
PubMed2004

Increased percentage of CD4+CD25+ regulatory T cells during septic shock is due to the decrease of CD4+CD25- lymphocytes.

OBJECTIVE: The elevation of the percentage of regulatory CD4+CD25+ T lymphocytes (Treg) has been recently described during septic shock. The objective of the present study was to investigate whether this increased percentage was due to Treg proliferation. DESIGN: Observational study. SETTING: Adult intensive care units in a university hospital. SUBJECTS: Patients with septic shock (n = 54) and healthy individuals (n = 30). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: In patients, we first confirmed the increased percentage of Treg among CD4+ lymphocytes in comparison with healthy individuals. Surprisingly, regarding absolute counting, we demonstrated that both T CD4+ lineages (CD25+ and CD25-) were diminished immediately after the onset of shock. Then, whereas Treg returned rapidly to healthy donors values, CD4+CD25- T lymphocytes remained dramatically reduced. Finally, Foxp3 (Treg-related gene) messenger RNA quantification enabled us to definitively rule out a lack of proliferation since it was not increased during shock. CONCLUSION: The increased percentage of Treg after shock is due not to their proliferation but to a decrease in CD4+CD25- T lymphocyte number. We hypothesize that it might be due to a resistance of Treg to apoptosis processes occurring during septic shock.

APACHE↗
PubMed2003

Calcitonin gene related peptide and N-procalcitonin modulate CD11b upregulation in lipopolysaccharide activated monocytes and neutrophils.

OBJECTIVE: Circulating levels of calcitonin gene related peptide (CGRP) and calcitonin precursors, including procalcitonin (PCT) and its free aminopeptide N-procalcitonin (N-PCT), have been found dramatically increased in septic patients. PCT is known to attenuate the chemotaxis of monocytes in response to chemoattractants. This study examined whether CGRP and N-PCT modulate the LPS-induced expression of CD11b, which is one of the major integrins involved in monocyte and neutrophil chemotaxis during a response to microbial infections. DESIGN AND SETTING: In vitro cell culture study in the immunology laboratory of a university hospital. PARTICIPANTS: Healthy volunteers. MEASUREMENTS AND RESULTS: We assessed the effects of N-PCT and CGRP on CD11b expression on monocytes and neutrophils after LPS (2 ng/ml) or fMLP (10(-8) M) challenges. We used a human whole blood model, and measurements were made by flow cytometry. Both peptides in a dose-dependent manner decreased the LPS- and fMLP-induced rise in CD11b in monocytes and neutrophils. As these peptides are thought to act by raising cAMP, we also mimicked their effects with the use of rolipram and forskolin and found similar results. CONCLUSIONS: These findings are in line with recent studies demonstrating anti-inflammatory properties for this family of peptides. CGRP and calcitonin precursors may function as factors suppressing the propagation of inflammation through the inhibition of several processes involved during a response to a bacterial stimulus.

Biomarkers↗