Cross-sectional reassessment after 4 years of clinical routine use of AQUIOS CL for absolute T cell quantitation in a university hospital

BACKGROUND

We had previously reported appropriate performances of automated AQUIOS CL cytometer (Beckman Coulter) for regulatory approval of absolute T cell enumeration. However, after 4 years of routine use, we still observed recurrent histogram anomalies that may affect both absolute values and T cell subset percentages results. The objective of the current study was thus to perform a cross-sectional evaluation of these graphical anomalies within a university hospital context, to assess their influence on results and ultimately to propose a standardized decision tree to circumvent graphical disturbances at the time of results validation.

METHODS

Eight hundred and sixty-two blood samples were prospectively analyzed on AQUIOS CL. Results were compared to (i) lymphocyte values from complete blood count; (ii) results from manual staining and analysis on Navios cytometer (Beckman Coulter); (iii) results after washing step and reacquisition on AQUIOS CL.

RESULTS

Nearly 75% analyses did not show any graphical anomaly. 20% had single anomaly on "Lymphs (45)" or "Lymphs EV" regions influencing T cells percentages and requiring manual re-gating of "CD3- capture" region. 5% showed concomitant "Lymphs EV" and "Lymphs (45)" anomalies influencing both T cell percentages and absolute counting and requiring additional staining and analysis on Navios. Finally, <1% presented with anomaly on "CD4/CD8" histogram or "CD3+ All" region, influencing both T cell percentages and absolute counting.

CONCLUSIONS

Around 25% AQUIOS CL results were flawed due to gating anomalies. In <5% cases, additional back-up procedures should be undertaken to ensure results validity. A simple decision-tree may help in guiding validation process.

Polyclonal expansion of TCR Vbeta 21.3+ CD4+ and CD8+ T cells is a hallmark of Multisystem Inflammatory Syndrome in Children

Multiple Inflammatory Syndrome in Children (MIS-C) is a delayed and severe complication of SARS-CoV-2 infection that strikes previously healthy children. As MIS-C combines clinical features of Kawasaki disease and Toxic Shock Syndrome (TSS), we aimed to compare the immunological profile of pediatric patients with these different conditions. We analyzed blood cytokine expression, and the T cell repertoire and phenotype in 36 MIS-C cases, which were compared to 16 KD, 58 TSS, and 42 COVID-19 cases. We observed an increase of serum inflammatory cytokines (IL-6, IL-10, IL-18, TNF-α, IFNγ, CD25s, MCP1, IL-1RA) in MIS-C, TSS and KD, contrasting with low expression of HLA-DR in monocytes. We detected a specific expansion of activated T cells expressing the Vβ21.3 T cell receptor β chain variable region in both CD4 and CD8 subsets in 75% of MIS-C patients and not in any patient with TSS, KD, or acute COVID-19; this correlated with the cytokine storm detected. The T cell repertoire returned to baseline within weeks after MIS-C resolution. Vβ21.3+ T cells from MIS-C patients expressed high levels of HLA-DR, CD38 and CX3CR1 but had weak responses to SARS-CoV-2 peptides in vitro. Consistently, the T cell expansion was not associated with specific classical HLA alleles. Thus, our data suggested that MIS-C is characterized by a polyclonal Vβ21.3 T cell expansion not directed against SARS-CoV-2 antigenic peptides, which is not seen in KD, TSS and acute COVID-19.

LACC1 deficiency links juvenile arthritis with autophagy and metabolism in macrophages

Juvenile idiopathic arthritis is the most common chronic rheumatic disease in children, and its etiology remains poorly understood. Here, we explored four families with early-onset arthritis carrying homozygous loss-of-expression mutations in LACC1. To understand the link between LACC1 and inflammation, we performed a functional study of LACC1 in human immune cells. We showed that LACC1 was primarily expressed in macrophages upon mTOR signaling. We found that LACC1 deficiency had no obvious impact on inflammasome activation, type I interferon response, or NF-κB regulation. Using bimolecular fluorescence complementation and biochemical assays, we showed that autophagy-inducing proteins, RACK1 and AMPK, interacted with LACC1. Autophagy blockade in macrophages was associated with LACC1 cleavage and degradation. Moreover, LACC1 deficiency reduced autophagy flux in primary macrophages. This was associated with a defect in the accumulation of lipid droplets and mitochondrial respiration, suggesting that LACC1-dependent autophagy fuels macrophage bioenergetics metabolism. Altogether, LACC1 deficiency defines a novel form of genetically inherited juvenile arthritis associated with impaired autophagy in macrophages.

Clinical significance of a single cerebrospinal fluid immunoglobulin band: A retrospective study

BACKGROUND

To demonstrate an inflammatory process in the central nervous system, the presence of at least two immunoglobulin (Ig) bands in the cerebrospinal fluid (CSF) is required. So far, the presence of a single abnormal Ig band is considered as negative.

OBJECTIVE

The objective was to assess retrospectively the significance of a single CSF Ig band in clinical practice.

METHODS AND RESULTS

Out of 10,286 CSF analyses, we retained 214 results with single Ig. An inflammatory neurological disorder was diagnosed in 41% of patients.

CONCLUSION

Despite a modest sensitivity, the presence of a single CSF Ig band may be a biomarker of an inflammatory mechanism and, as such, may prompt the clinician to repeat the analysis when the clinical context remains suggestive.

Contribution of rare and predicted pathogenic gene variants to childhood-onset lupus: a large, genetic panel analysis of British and French cohorts

BACKGROUND

Systemic lupus erythematosus (SLE) is a rare immunological disorder and genetic factors are considered important in its causation. Monogenic lupus has been associated with around 30 genotypes in humans and 60 in mice, while genome-wide association studies have identified more than 90 risk loci. We aimed to analyse the contribution of rare and predicted pathogenic gene variants in a population of unselected cases of childhood-onset SLE.

METHODS

For this genetic panel analysis we designed a next-generation sequencing panel comprising 147 genes, including all known lupus-causing genes in humans, and potentially lupus-causing genes identified through GWAS and animal models. We screened 117 probands fulfilling American College of Rheumatology (ACR) criteria for SLE, ascertained through British and French cohorts of childhood-onset SLE, and compared these data with those of 791 ethnically matched controls from the 1000 Genomes Project and 574 controls from the FREX Consortium.

FINDINGS

After filtering, mendelian genotypes were confirmed in eight probands, involving variants in C1QA, C1QC, C2, DNASE1L3, and IKZF1. Seven additional patients carried heterozygous variants in complement or type I interferon-associated autosomal recessive genes, with decreased concentrations of the encoded proteins C3 and C9 recorded in two patients. Rare variants that were predicted to be damaging were significantly enriched in the childhood-onset SLE cohort compared with controls; 25% of SLE probands versus 5% of controls were identified to harbour at least one rare, predicted damaging variant (p=2·98 × 10-11). Inborn errors of immunity were estimated to account for 7% of cases of childhood-onset SLE, with defects in innate immunity representing the main monogenic contribution.

INTERPRETATION

An accumulation of rare variants that are predicted to be damaging in SLE-associated genes might contribute to disease expression and clinical heterogeneity.

FUNDING

European Research Council.

Clinical Heterogeneity of Immune Dysregulation, Polyendocrinopathy, Enteropathy, X-Linked Syndrome: A French Multicenter Retrospective Study

Objective

Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is an autoimmune disease caused by mutations in the forkhead box protein 3 gene (FOXP3), which encodes a key regulator of immune tolerance. The aim of this study was to describe the clinical heterogeneity of the disease in a national French cohort.

Methods

Multicenter retrospective study of patients diagnosed with IPEX syndrome caused by mutations in FOXP3.

Results

Thirty children from 26 families were included. Age at disease onset (median [first to third quartile]) was 1.5 mo [0–84] and at death 3.5 years [0–10.5] (n = 15) indicating a high heterogeneity. Initial presentation was diarrhoea (68%), type 1 diabetes (T1D; 25%), skin lesions (7%) and nephropathy (3%). During the course of the disease the following main symptoms were observed: diarrhoea (100%), skin lesions (85%), T1DM (50%), severe food allergies (39%), haematological disorders (28%), nephropathies (25%), hepatitis (14%) as well as the presence of a variety of autoantibodies. Immunosuppressive mono- or combination therapy led to improvement in eight children. Three boys displayed a stable disease course without any immunosuppressive medication. Overall 10-year survival rate was 43% (42% in transplanted patients and 52% in patients on immunosuppressive therapy). Five out of 22 identified FOXP3 mutations have not been described yet: c.−23 + 1G > A, c.−23 + 5G > A, c.264delC, c.1015C > T and c.1091A > G. The first two produced atypical, attenuated phenotypes. Missense and frameshift mutations affecting the forkhead domain were associated with poor survival (Gehan–Wilcoxon p = 0.002).

Conclusion

The broad phenotypic heterogeneity of IPEX raises questions about modifying factors and justifies early FOXP3 sequencing in suspected cases.

TTC7A mutation must be considered in patients with repeated intestinal atresia associated with early inflammatory bowel disease: Two new case reports and a literature review

TTC7A mutations cause multiple neonatal intestinal atresias with early inflammatory bowel disease and severe combined immunodeficiency. There are no treatment protocols for this rare disease. Two new cases are described for which radical early treatment measures - total enterectomy, home parenteral nutrition, immunoglobulin therapy and intravenous antibiotic prophylaxis - have allowed both patients to develop optimally.

Septic Shock Shapes B Cell Response toward an Exhausted-like/Immunoregulatory Profile in Patients

Septic shock is accompanied by the development of immune dysfunctions whose intensity and duration are associated with increased risk of secondary infections and mortality. Although B lymphocytes play a pivotal role in the immune response to infections, no comprehensive exploration of circulating B cell status has been performed during the immunosuppressive phase of septic shock. Thus, our aim was to extensively characterize the phenotype and function of B cells in septic shock, including IL-10 production. Circulating B lymphocyte phenotype and function were evaluated by flow cytometry on fresh whole blood and after ex vivo stimulation in adult septic shock patients sampled at day 1, 3, and 6 after the onset of shock. The circulating B cell number was reduced in septic shock patients, whereas the B cell proportion among total lymphocytes was increased. The remaining circulating B lymphocytes presented with decreased MHC class II expression and increased CD21^low CD95^high exhausted-like phenotype but showed no change in maturation status. Circulating B cell functions were markedly altered after sepsis with reduced ex vivo activation and proliferation capacities. Finally, B cell response after septic shock was characterized by a clear plasmacytosis and an increased IL-10 production in remaining B cells from patients after ex vivo stimulation. During the sepsis-induced immunosuppression phase, B cell response is altered and is oriented toward an exhausted-like/immunoregulatory profile. Further studies are now needed to confirm the immunoregulatory properties of B lymphocytes and evaluate their role in sepsis-induced immunosuppression.

Familial and syndromic lupus share the same phenotype as other early-onset forms of lupus

OBJECTIVE

Studies of early-onset systemic lupus erythematosus (SLE) have identified monogenic forms of the disease. The primary objective of this study was to compare the clinical and laboratory features of the first patients included in the GENIAL/LUMUGENE cohort to those reported in previous publications. The secondary objective was to determine whether subgroups with a distinctive pattern of clinical and biological features are seen in predominantly genetic forms of SLE.

METHODS

GENIAL/LUMUGENE is a French nationwide study of the clinical, immunological, and genetic features of juvenile-onset SLE (clinicaltrials.gov #NCT01992666). Clinical and laboratory data from the first 64 patients younger than 18 years who were included in the first part of the study were collected retrospectively. Predefined criteria were used to divide the patients into three subgroups: syndromic SLE (n=10) and familial SLE (n=12) - both presumed to have a strong genetic component - and other forms of early-onset SLE (n=42).

RESULTS

The predefined criteria for identifying subgroups based on knowledge of the clinical and epidemiological features of monogenic SLE showed a significantly younger age at onset in syndromic SLE (P<0.05) and a lower frequency of joint manifestations in familial SLE.

CONCLUSIONS

In this study, clinical and epidemiological data alone failed to identify a specific patient subgroup characterized by the same disease presentation or progression. This result may be related to the small sample size or indicate marked heterogeneity of juvenile-onset SLE. Genetic studies using new sequencing techniques in these patients might identify genetic factors responsible for marked phenotypic variability.

Evaluation of a novel automated volumetric flow cytometer for absolute CD4+ T lymphocyte quantitation

BACKGROUND

Bead-based single platform cytometry technology (SPT) is the gold standard when performing CD4 absolute counting. However, it presents drawbacks as precision depends on various critical steps (for example, pipetting methodology, overtime stability of beads, stability of fluidics, regular recalibration…) and thus requires skilled operators. The fully automated volumetric SPT AQUIOS CL (Beckman Coulter) has recently emerged as an alternative with no need of beads. It may help improving results standardisation and fulfilling requirements for certification (ISO 15189). In this study, we assessed SPT AQUIOS CL performances in accordance to requirements for ISO 15189 accreditation.

METHODS

We evaluated repeatability and reproducibility (precision), bias (trueness), uncertainty (total error), range limits (linearity, quantification, detection limits), and inter-reagent/inter-sample contaminations in enumerating CD4+ T-cells. Concomitantly, we compared AQUIOS CL CD4+ T-cell values with the results obtained with our routine bead-based SPT (that is, FC500 Beckman Coulter, bead-based SPT), on blood samples from 148 patients representative of clinical laboratory routine workload.

RESULTS

Every result (repeatability, reproducibility, trueness, total error) was below the acceptable thresholds proposed in international recommendations. Contamination results and range limits (linearity, quantification, and detection limits) were all found perfectly suitable to routine analysis. The comparison between AQUIOS CL and FC500 exhibited excellent correlation and agreement (Pearson R = 0.99, P < 0.001; Lin's concordance correlation coefficient: Lin ρ_c  = 0.991, Cb = 0.999), and Bland-Altman analysis did not reveal any systematic error.

CONCLUSIONS

Our results demonstrate that, upon subsequent validation in more routine conditions, the AQUIOS CL could be a suitable tool for clinical flow cytometry laboratories facing accreditation process. © 2016 International Clinical Cytometry Society.

PRKDC mutations associated with immunodeficiency, granuloma, and autoimmune regulator-dependent autoimmunity

BACKGROUND

PRKDC encodes for DNA-dependent protein kinase catalytic subunit (DNA-PKcs), a kinase that forms part of a complex (DNA-dependent protein kinase [DNA-PK]) crucial for DNA double-strand break repair and V(D)J recombination. In mice DNA-PK also interacts with the transcription factor autoimmune regulator (AIRE) to promote central T-cell tolerance.

OBJECTIVE

We sought to understand the causes of an inflammatory disease with granuloma and autoimmunity associated with decreasing T- and B-cell counts over time that had been diagnosed in 2 unrelated patients.

METHODS

Genetic, molecular, and functional analyses were performed to characterize an inflammatory disease evocative of a combined immunodeficiency.

RESULTS

We identified PRKDC mutations in both patients. These patients exhibited a defect in DNA double-strand break repair and V(D)J recombination. Whole-blood mRNA analysis revealed a strong interferon signature. On activation, memory T cells displayed a skewed cytokine response typical of TH2 and TH1 but not TH17. Moreover, mutated DNA-PKcs did not promote AIRE-dependent transcription of peripheral tissue antigens in vitro. The latter defect correlated in vivo with production of anti-calcium-sensing receptor autoantibodies, which are typically found in AIRE-deficient patients. In addition, 9 months after bone marrow transplantation, patient 1 had Hashimoto thyroiditis, suggesting that organ-specific autoimmunity might be linked to nonhematopoietic cells, such as AIRE-expressing thymic epithelial cells.

CONCLUSION

Deficiency of DNA-PKcs, a key AIRE partner, can present as an inflammatory disease with organ-specific autoimmunity, suggesting a role for DNA-PKcs in regulating autoimmune responses and maintaining AIRE-dependent tolerance in human subjects.

Increased Regulatory T-Cell Percentage Contributes to Poor CD4(+) Lymphocytes Recovery: A 2-Year Prospective Study After Introduction of Antiretroviral Therapy

Background. The primary aim of this study was to determine the impact of regulatory T cells (Tregs) percentage on immune recovery in human immunodeficiency virus (HIV)-infected patients after antiretroviral therapy introduction.

Methods. A 2-year prospective study was conducted in HIV-1 chronically infected naive patients with CD4 count <500 cells/mm³. Regulatory T cells were identified as CD4⁺CD25^highCD127^low cells among CD4⁺ lymphocytes. Effect of Treg percentage at inclusion on CD4 evolution overtime was analyzed using a mixed-effect Poisson regression for count data.

Results. Fifty-eight patients were included (median CD4 = 293/mm³, median Treg percentage = 6.1%). Percentage of Treg at baseline and CD4 nadir were independently related to the evolution of CD4 absolute value according to time: (1) at any given nadir CD4 count, 1% increase of initial Treg was associated with a 1.9% lower CD4 absolute value at month 24; (2) at any given Treg percentage at baseline, 10 cell/mm³ increase of CD4 nadir was associated with a 2.4% increase of CD4 at month 24; and (3) both effects did not attenuate with time. The effect of Treg at baseline on CD4 evolution was as low as the CD4 nadir was high.

Conclusions. Regulatory T-cell percentage at baseline is a strong independent prognostic factor of immune recovery, particularly among patients with low CD4 nadir.

Mutations in CECR1 associated with a neutrophil signature in peripheral blood

BACKGROUND

A reduction of ADA2 activity due to autosomal recessive loss of function mutations in CECR1 results in a newly described vasculopathic phenotype reminiscent of polyarteritis nodosa, with manifestations ranging from fatal systemic vasculitis with multiple strokes in children to limited cutaneous disease in middle-aged individuals. Evidence indicates that ADA2 is essential for the endothelial integrity of small vessels. However, CECR1 is not expressed, nor is the ADA2 protein detectable, in cultured human endothelial cells, thus implicating additional cell types or circulating factors in disease pathogenesis.

METHODS

Considering the phenotypic overlap of ADA2 deficiency with the type I interferonopathy Aicardi-Goutières syndrome due to mutations in SAMHD1, we looked for the presence of an interferon signature in the peripheral blood of two newly ascertained ADA2-deficient patients.

RESULTS

We identified biallelic CECR1 mutations in two patients consistent with ADA2 deficiency. Both patients demonstrated an upregulation of interferon stimulated gene transcripts in peripheral blood. More strikingly however, genome-wide analysis revealed a marked overexpression of neutrophil-derived genes, suggesting that the vasculitis seen in ADA2 deficiency may be an indirect effect resulting from chronic and marked activity of neutrophils.

CONCLUSIONS

We hypothesise that ADA2 may act as a regulator of neutrophil activation, and that a reduction of ADA2 activity results in significant endothelial damage via a neutrophil-driven process.

B-cell subpopulations in children: National reference values

Peripheral B-lymphocytes undergo a series of changes during the first few years of life. Encounters with foreign antigens lead to maturation and differentiation. Several primary antibody deficiencies (PADs) affecting B-cell development are associated with abnormalities in the composition and/or differentiation of B-cell compartments. The most recent international classifications of primary immunodeficiencies (PIDs) and common variable immunodeficiencies (CVID) have highlighted the importance of B-cell immunophenotyping and age-specific reference intervals for diagnostic purposes. We established national reference values for memory B-cell subpopulations, on the basis of CD27 and surface IgD expression in the peripheral blood of 242 healthy children. We report here the absolute counts and percentages of naive, switched and non-switched memory B-cells for seven age groups, from neonates to adults. We found that the naive B-cells percentage declined between the ages of 6 months and 8 years, after which it remained stable at about 70–80%. Memory B-cells are already present at birth and their numbers increase throughout childhood, stabilizing between the ages of 12 and 18 years. The definition of reference intervals for pediatric B-cell levels should facilitate the screening and diagnosis of various B-cell immunodeficiencies. This multicenter study, providing national reference values, should thus facilitate immunological diagnosis in children.

Immunological abnormalities associated with hereditary haemorrhagic telangiectasia

OBJECTIVE

Hereditary haemorrhagic telangiectasia (HHT) is a genetic disorder related to mutations in one of the coreceptors to the transforming growth factor-β superfamily (ALK1 or endoglin). Besides the obvious vascular symptoms (epistaxis and arteriovenous malformations), patients have an unexplained high risk of severe bacterial infections. The aim of the study was to assess the main immunological functions of patients with HHT using the standard biological tests for primary immunodeficiencies.

DESIGN, SETTING AND SUBJECTS

A prospective single-centre study of 42 consecutive adult patients with an established diagnosis of HHT was conducted at the National French HHT Reference Center (Lyon). Lymphocyte subpopulations and proliferation capacity, immunoglobulin levels and neutrophil and monocyte phagocytosis, oxidative burst and chemotaxis were assessed.

RESULTS

Innate immunity was not altered in patients with HHT. With regard to adaptive immunity, significant changes were seen in immunological parameters: primarily, a lymphopenia in patients with HHT compared with healthy control subjects affecting mean CD4 (642 cells μL(-1) vs. 832 cells μL(-1) , P < 0.001), CD8 (295 cells μL(-1) vs. 501 cells μL(-1) , P < 0.0001) and natural killer (NK) cells (169 cells μL(-1) vs. 221 cells μL(-1) , P < 0.01), associated with increased levels of immunoglobulins G and A. This lymphopenia mainly concerned naïve T cells. Proliferation capacities of lymphocytes were normal. Lymphopenic patients had a higher frequency of iron supplementation but no increase in infection rate. Lower levels of immunoglobulin M and a higher rate of pulmonary arteriovenous malformations were found amongst patients with a history of severe infection.

CONCLUSIONS

Patients with HHT exhibit immunological abnormalities including T CD4, T CD8 and NK cell lymphopenia and increased levels of immunoglobulins G and A. The observed low level of immunoglobulin M requires further investigation to determine whether it is a specific risk factor for infection in HHT.

Protein kinase cδ deficiency causes mendelian systemic lupus erythematosus with B cell-defective apoptosis and hyperproliferation

OBJECTIVE

Systemic lupus erythematosus (SLE) is a prototype autoimmune disease that is assumed to occur via a complex interplay of environmental and genetic factors. Rare causes of monogenic SLE have been described, providing unique insights into fundamental mechanisms of immune tolerance. The aim of this study was to identify the cause of an autosomal-recessive form of SLE.

METHODS

We studied 3 siblings with juvenile-onset SLE from 1 consanguineous kindred and used next-generation sequencing to identify mutations in the disease-associated gene. We performed extensive biochemical, immunologic, and functional assays to assess the impact of the identified mutations on B cell biology.

RESULTS

We identified a homozygous missense mutation in PRKCD, encoding protein kinase δ (PKCδ), in all 3 affected siblings. Mutation of PRKCD resulted in reduced expression and activity of the encoded protein PKCδ (involved in the deletion of autoreactive B cells), leading to resistance to B cell receptor- and calcium-dependent apoptosis and increased B cell proliferation. Thus, as for mice deficient in PKCδ, which exhibit an SLE phenotype and B cell expansion, we observed an increased number of immature B cells in the affected family members and a developmental shift toward naive B cells with an immature phenotype.

CONCLUSION

Our findings indicate that PKCδ is crucial in regulating B cell tolerance and preventing self-reactivity in humans, and that PKCδ deficiency represents a novel genetic defect of apoptosis leading to SLE.

CD4+CD25+CD127- assessment as a surrogate phenotype for FOXP3+ regulatory T cells in HIV-1 infected viremic and aviremic subjects

BACKGROUND

Although likely pivotal, the role of regulatory T cells (Tregs) in HIV pathogenesis remains elusive. This can be partly explained by analytical issues regarding their phenotypic identification in clinical studies. Instead of intracellular FOXP3 staining, CD4+CD25+CD127- phenotype has been proposed as an alternative to identify Tregs in clinical samples. However, its use remains controversial in viremic patients. Therefore, the objective of the present study was to assess the correlation between frequencies of CD4+CD25+CD127- and CD4+CD25+FOXP3+ lymphocytes in viremic and matched aviremic HIV-infected patients.

METHODS

Peripheral blood was collected from HIV-1 infected patients. Eleven viremic patients (Viral Load > 40 copies/mL) were matched (age, sex, CD4+ cell number) with 8 aviremic patients under highly active antiretroviral therapy (HAART). Fresh whole blood was immediately stained to analyze by flow cytometry the correlation between CD4+CD25+CD127- and the reference phenotype CD4+CD25+FOXP3+ lymphocytes in the same tube (four color staining CD4/CD25/CD127/FOXP3 for concomitant analysis of cell surface and intracellular markers).

RESULTS

In both groups, no significant differences were observed when comparing CD4+CD25+CD127- and CD4+CD25+FOXP3+ cell frequencies. In line, a strong correlation between CD4+CD25+CD127- and CD4+CD25+FOXP3+ lymphocyte percentages was observed in the whole patient population (r: 0.948, P < 0.001) or each group separately: aviremic (r: 0.968, P < 0.001), viremic (r: 0.9, P < 0.001). Finally, we found that most CD4+FOXP3+ cells were indeed CD25+CD127-, both in viremic and aviremic groups (88.5% and 90.9%, respectively).

CONCLUSIONS

We observed that CD4+CD25+CD127- phenotype is a good and easy-to-perform surrogate identification strategy for FOXP3+ regulatory T cells in both viremic and aviremic HIV-1-infected subjects. Thus, it represents a useful tool for monitoring Tregs in clinical research studies based on large cohorts of patients prospectively monitored, including HIV-infected subjects.

Programmed death-1 levels correlate with increased mortality, nosocomial infection and immune dysfunctions in septic shock patients

INTRODUCTION

Septic shock remains a major health care problem worldwide. Sepsis-induced immune alterations are thought to play a major role in patients' mortality and susceptibility to nosocomial infections. Programmed death-1 (PD-1) receptor system constitutes a newly described immunoregulatory pathway that negatively controls immune responses. It has recently been shown that PD-1 knock-out mice exhibited a lower mortality in response to experimental sepsis. The objective of the present study was to investigate PD-1-related molecule expressions in septic shock patients.

METHODS

This prospective and observational study included 64 septic shock patients, 13 trauma patients and 49 healthy individuals. PD-1-related-molecule expressions were measured by flow cytometry on circulating leukocytes. Plasmatic interleukin (IL)-10 concentration as well as ex vivo mitogen-induced lymphocyte proliferation were assessed.

RESULTS

We observed that septic shock patients displayed increased PD-1, PD-Ligand1 (PD-L1) and PD-L2 monocyte expressions and enhanced PD-1 and PD-L1 CD4+ T lymphocyte expressions at day 1-2 and 3-5 after the onset of shock in comparison with patients with trauma and healthy volunteers. Importantly, increased expressions were associated with increased occurrence of secondary nosocomial infections and mortality after septic shock as well as with decreased mitogen-induced lymphocyte proliferation and increased circulating IL-10 concentration.

CONCLUSIONS

These findings indicate that PD-1-related molecules may constitute a novel immunoregulatory system involved in sepsis-induced immune alterations. Results should be confirmed in a larger cohort of patients. This may offer innovative therapeutic perspectives on the treatment of this hitherto deadly disease.

Proatrial natriuretic peptide is a better predictor of 28-day mortality in septic shock patients than proendothelin-1

BACKGROUND

Septic shock is a major health care problem that affects a heterogeneous population of patients. To improve sepsis management, a key point is to decrease this heterogeneity by stratifying patients according to specific criteria, such as appropriate biomarkers. As the early phase of septic shock is characterized by cardiovascular dysfunction, precursors of vasoactive hormones represent interesting candidates. The objective of the present study was to concomitantly assess the predictive value of C-terminal proendothelin-1 and midregional proatrial natriuretic peptide (CT-proET-1 and MR-proANP, respectively vasoconstrictor and vasodilator) on 28-day mortality following septic shock.

METHODS

In this observational study which included 99 patients, concentrations of MR-proANP and CT-proET-1 were measured using an immunoluminometric assay three times within the first week after the onset of septic shock.

RESULTS

While MR-proANP concentrations were significantly increased in non-survivors in comparison with survivors, no differences were noted for CT-proET-1. Increased MR-proANP concentrations were significantly associated with mortality after both univariate and multivariate analyses, adjusted for usual clinical confounders [SAPS II (simplified acute physiology score II), SOFA (sepsis-related organ failure assessment) scores and number of co-morbidities].

CONCLUSIONS

In septic shock patients, MR-proANP appears to be a good predictor of 28-day mortality, whereas CT-proET-1 does not present any predictive value during monitoring.

Preferential increase in memory and regulatory subsets during T-lymphocyte immune reconstitution after Thymoglobulin induction therapy with maintenance sirolimus vs cyclosporine

BACKGROUND

Sirolimus maintenance therapy with Thymoglobulin induction is a promising regimen that may preserve renal function. Data are lacking, however, about the immunologic effects of combined Thymoglobulin-sirolimus.

METHODS

In a 12-month, prospective, randomised, open-label, single-centre pilot study, de novo deceased-donor kidney transplant patients were randomised to receive cyclosporine or sirolimus, with Thymoglobulin induction, mycophenolate mofetil and corticosteroids. Flow cytometry analysis of peripheral blood was used to evaluate immune reconstitution.

RESULTS

Nineteen patients were recruited (sirolimus 9, cyclosporine 10). Reconstitution of the CD4(+) T-lymphocyte subset was significantly lower with sirolimus versus cyclosporine over year 1, but CD8(+) reconstitution did not differ significantly between groups. The proportion of naïve CD4(+) T-lymphocytes showed an initial decrease with sirolimus versus cyclosporine. Naïve CD8(+) T-lymphocytes increased versus baseline in the cyclosporine cohort at months 1 and 3, but remained unchanged with sirolimus. Memory CD4(+) T-lymphocytes occurred more frequently in sirolimus- versus cyclosporine-treated patients during year 1. The proportion of memory CD8(+) T-lymphocytes decreased at months 1 and 3 compared to baseline in the CsA arm, but did not change in the sirolimus cohort. By month 12, the proportion of both naïve and memory CD4(+) and CD8(+) T-lymphocytes had become similar with sirolimus or cyclosporine. There were fewer naïve B-lymphocytes in the sirolimus cohort and more CD19(-)IgD(+/-)CD27(+) memory B-lymphocytes.

CONCLUSIONS

In this small population, homeostatic reconstitution after Thymoglobulin induction showed disproportionately high recovery of memory T-lymphocyte subsets during sirolimus therapy, which may explain the higher rejection rate seen with sirolimus versus cyclosporine following kidney transplantation.

Human mesenchymal stem cells and immunosuppressive drug interactions in allogeneic responses: an in vitro study using human cells

OBJECTIVES

The use of mesenchymal stem cells (MSC), which display immunosuppressive activity, seems to be a promising therapeutic approach in solid organ transplantation. However, little is known about their interactions with immunosuppressive drugs. The objective of this study was to assess these interactions in allogeneic responses.

METHODS

We studied the effects on alloimmune responses in mixed lymphocyte reactions of MSC plus five agents-cyclosporine, tacrolimus, rapamycin, mycophenolate acid (MPA), and dexamethasone (DEX).

RESULTS

Human MSC isolated from bone marrow were characterized by their phenotype and their ability to differentiate into adipocytes or osteoblastes. MSC plus the agents inhibited allogeneic lymphocyte proliferation in a dose-dependent manner. Calcineurin inhibitors and rapamycin antagonized the inhibitory effect of MSC, whereas MPA promoted it and DXM did not modify it.

CONCLUSION

MPA seems to be the best immunosuppressant to associated with MSC for transplanted patients.

Percentage of regulatory T cells CD4+CD25+CD127- in HIV-infected patients is not reduced after cryopreservation

Interest in regulatory T cells (Treg) has been continuously growing over the last 10years. In particular, a role for Treg has been recently reported in HIV. It is crucial to investigate their conservation over time, once sampled and purified. The objective of the present study was to investigate whether cryopreservation may modify recognition and measurement of relative frequency of Treg (CD4(+)CD25(+)CD127(-)) among PBMCs purified from 17 HIV-infected patients. Ours results indicate that cryopreservation does not affect this specific T lymphocyte subset.

Assessment of pro-vasopressin and pro-adrenomedullin as predictors of 28-day mortality in septic shock patients

PURPOSE

Improvements in survival after septic shock will most likely rely on our capacity to manage individualized therapies based on the measurement of rapidly accessible biomarkers. As the early phase of septic shock is dominated by severe alterations of the cardiovascular system, the predictive value for mortality of pro-vasopressin (pro-AVP) and pro-adrenomedullin (pro-ADM), two vasoactive pro-hormones, was assessed.

METHODS

In 99 consecutive patients, pro-hormone concentrations were measured (immunoluminometric assay) three times within the first week after the onset of septic shock.

RESULTS

Pro-AVP and pro-ADM concentrations were significantly increased in non-survivors in comparison with survivors and were significantly associated with mortality after both univariate and multivariate analysis. Importantly, when assessed as a pair, pro-ADM and pro-AVP were even more informative.

CONCLUSIONS

Both Pro-ADM and pro-AVP appear to be good biomarkers for the prediction of 28-day mortality after septic shock. However, their association in a single variable tends to improve their predictive capacity.

Neutralising antibodies to interferon β in multiple sclerosis

Interferon beta (IFNbeta) therapy for multiple sclerosis (MS) is associated with a potential for the development of neutralising antibodies (NAbs) that negatively affect therapy. Several factors influence the development of NAbs, such as lack of complete sequence homology with the endogenous IFNbeta sequence, frequency of administration, level of dose and formulation of IFNbeta. Taken together, the evidence that NAb status reduces clinical efficacy in MS patients is strong. Standardised assays for NAbs are lacking, and titres vary over time. NAb testing is a critical component of care for MS patients because it provides information on one of the most important factors determining clinical responsiveness to IFNbeta therapy. This expert panel report attempts to move the field towards resolution of the remaining issues and considers several aspects of NAbs, including their clinical relevance, factors influencing immunogenicity, assays to quantify NAbs and the definition of clinically relevant titres.

Bone marrow CD34+/B220+ progenitors target the inflamed brain and display in vitro differentiation potential toward microglia

Recent evidence indicates that microglial cells may not derive from blood circulating mature monocytes as they express features of myeloid progenitors. Here, we observed that a subpopulation of microglial cells expressed CD34 and B220 antigens during brain development. We thus hypothesized that microglia, or a subset of microglial cells, originate from blood circulating CD34+/B220+ myeloid progenitors, which could target the brain under developmental or neuroinflammatory conditions. Using experimental allergic encephalomyelitis (EAE) as a model of chronic neuroinflammation, we found that a discrete population of CD34+/B220+ cells expands in both blood and brain of diseased animals. In EAE mice, intravenous transfer experiments showed that macrophage-colony stimulating factor (M-CSF) -expanded CD34+ myeloid progenitors target the inflamed central nervous system (CNS) while keeping their immature phenotype. Based on these results, we then assessed whether CD34+/B220+ cells display in vitro differentiation potential toward microglia. For this purpose, CD34+/B220+ cells were sorted from M-CSF-stimulated bone marrow (BM) cultures and exposed to a glial cell conditioned medium. Under these experimental conditions, CD34+/B220+ cells were able to differentiate into microglial-like cells showing the morphological and phenotypic features of native microglia. Overall, our data suggest that under developmental or neuroinflammatory conditions, a subpopulation of microglial cells derive from CNS-invading CD34+/B220+ myeloid progenitors.

A role for the neuronal protein collapsin response mediator protein 2 in T lymphocyte polarization and migration

The semaphorin-signaling transducer collapsin response mediator protein 2 (CRMP2) has been identified in the nervous system where it mediates Sema3A-induced growth cone navigation. In the present study, we provide first evidence that CRMP2 is present in the immune system and plays a critical role in T lymphocyte function. CRMP2 redistribution at the uropod in polarized T cells, a structural support of lymphocyte motility, suggests that it may regulate T cell migration. This was evidenced in primary T cells by small-interfering RNA-mediated CRMP2 gene silencing and blocking Ab, as well as CRMP2 overexpression in Jurkat T cells tested in a chemokine- and semaphorin-mediated transmigration assay. Expression analysis in PBMC from healthy donors showed that CRMP2 is enhanced in cell subsets bearing the activation markers CD69+ and HLA-DR+. Heightened expression in T lymphocytes of patients suffering from neuroinflammatory disease with enhanced T cell-transmigrating activity points to a role for CRMP2 in pathogenesis. The elucidation of the signals and mechanisms that control this pathway will lead to a better understanding of T cell trafficking in physiological and pathological situations.

How to drain without lymphatics? Dendritic cells migrate from the cerebrospinal fluid to the B-cell follicles of cervical lymph nodes

The lack of draining lymphatic vessels in the central nervous system (CNS) contributes to the so-called "CNS immune privilege." However, despite such a unique anatomic feature, dendritic cells (DCs) are able to migrate from the CNS to cervical lymph nodes through a yet unknown pathway. In this report, labeled bone marrow-derived myeloid DCs were injected stereotaxically into the cerebrospinal fluid (CSF) or brain parenchyma of normal rats. We found that DCs injected within brain parenchyma migrate little from their site of injection and do not reach cervical lymph nodes. In contrast, intra-CSF-injected DCs either reach cervical lymph nodes or, for a minority of them, infiltrate the subventricular zone, where neural stem cells reside. Surprisingly, DCs that reach cervical lymph nodes preferentially target B-cell follicles rather than T-cell-rich areas. This report sheds a new light on the specific role exerted by CSF-infiltrating DCs in the control of CNS-targeted immune responses.

Déficit immunitaire commun variable avec manifestations auto-immunes : étude de neuf observations ; intérêt d’un immunophénotypage spécifique des lymphocytes B circulants chez sept patients

PURPOSE

Autoimmune manifestations (AIM) are associated to common variable immunodeficiency (CVI) in about 20 to 25% of the cases. This study presents the clinical, biological characteristics and the evolution of nine patients developing CVI and AIM. A peripheral B-cell compartment analysis has been performed in seven cases.

METHOD

This multicenter retrospective study analyses nine patients, six men and three women, within a population of 32 CVI.

RESULTS

The mean age was 27 years at the time of diagnosis of AIM and 30 years at the time of diagnosis of CVI. The diagnosis of AIM preceded the diagnosis of CVI in five cases. Thirteen AIM of different types were observed: autoimmune hemolytic anemia (AHA, 3), immune thrombocytopenic purpura (ITP, 2), Evan's syndrome (2), primary biliary cirrhosis (1), rheumatoid arthritis (1), alopecia totalis (1), myasthenia gravis (1). The peripheral B-cell compartment was investigated in seven patients: five patients with autoimmune cytopenia presented with a diminution of memory B cells (CD27+IgD-) and immature B cells (CD21-) levels; the patient with primary biliary cirrhosis and myasthenia gravis had only a diminution of memory B cells level; the last patient with ITP presented with a normal level of memory B cells. Five among the seven patients with autoimmune cytopenia required a specific treatment using corticosteroids, high dosages of intravenous immunoglobulin, then splenectomy after failure of the medical management, with severe infectious complications in one case.

CONCLUSION

The association of AIM and CVI is not fortuitous. The most common AIM is autoimmune cytopenia. The peripheral B-cell compartment analyses show that a majority of patients have a defect in memory B-cells. Treatment regimens are not standardized and splenectomy increases the risk of infectious complications.

[Astrocytes, cells involved in neuro-immune interactions in the central nervous system]

The astrocyte, the major glial cell in the central nervous system, may influence many aspects of inflammation and immune reactivity within the brain. We have established a model of chronically activated T lymphocytes, interacting with neural cells of diverse origin to study the complex immune regulatory system suspected to lead to neuroinflammatory diseases. We show that human astrocytes became reactive following T cell contact, secreting proinflammatory cytokines, matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinase (TIMP). The altered MMP/TIMP system was shown to be involved in deleterious effects displayed by activated T cells towards human multipotent neural precursers by controlling their sensitivity to T cell-induced Fas-mediated apoptosis. MMP/TIMP was suspected to stabilize Fas at the cell membrane. In a model of mixed rat glial cells in primary culture (astrocytes, oligodendrocytes), activated T lymphocytes induced the collapse of processes and the death of immature oligodendrocytes. These effects were associated with upregulation of Fas at the cell surface of oligodendrocytes and secretion of MMP and TIMP by astrocytes. By amplifying the expression of inflammatory molecules including the MMP/TIMP system, astrocytes appear to be a crucial relay in the deleterious molecular cascade triggered by activated T lymphocytes. Detection of altered MMP/TIMP in patients suffering from myelopathy associated with retroviral infection (HTLV-1) strongly suggests its involvement in the physiopathological process of the disease.

Human T-cell lymphotropic virus type 1-infected T lymphocytes impair catabolism and uptake of glutamate by astrocytes via Tax-1 and tumor necrosis factor alpha

Human T-cell lymphotropic virus type 1 (HTLV-1) is the causative agent of a chronic progressive myelopathy called tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM). In this disease, lesions of the central nervous system (CNS) are associated with perivascular infiltration by lymphocytes. We and others have hypothesized that these T lymphocytes infiltrating the CNS may play a prominent role in TSP/HAM. Here, we show that transient contact of human or rat astrocytes with T lymphocytes chronically infected by HTLV-1 impairs some of the major functions of brain astrocytes. Uptake of extracellular glutamate by astrocytes was significantly decreased after transient contact with infected T cells, while the expression of the glial transporters GLAST and GLT-1 was decreased. In two-compartment cultures avoiding direct cell-to-cell contact, similar results were obtained, suggesting possible involvement of soluble factors, such as cytokines and the viral protein Tax-1. Recombinant Tax-1 and tumor necrosis factor alpha (TNF-alpha) decreased glutamate uptake by astrocytes. Tax-1 probably acts by inducing TNF-alpha, as the effect of Tax-1 was abolished by anti-TNF-alpha antibody. The expression of glutamate-catabolizing enzymes in astrocytes was increased for glutamine synthetase and decreased for glutamate dehydrogenase, the magnitudes of these effects being correlated with the level of Tax-1 transcripts. In conclusion, Tax-1 and cytokines produced by HTLV-1-infected T cells impair the ability of astrocytes to manage the steady-state level of glutamate, which in turn may affect neuronal and oligodendrocytic functions and survival.