Cécile Contin-Bordes

OX40 Ligand Contributes to Human Lupus Pathogenesis by Promoting T Follicular Helper Response

Increased activity of T follicular helper (Tfh) cells plays a major pathogenic role in systemic lupus erythematosus (SLE). However, the mechanisms that cause aberrant Tfh cell responses in SLE remain elusive. Here we showed the OX40 ligand (OX40L)-OX40 axis contributes to the aberrant Tfh response in SLE. OX40L was expressed by myeloid antigen-presenting cells (APCs), but not B cells, in blood and in inflamed tissues in adult and pediatric SLE patients. The frequency of circulating OX40L-expressing myeloid APCs positively correlated with disease activity and the frequency of ICOS(+) blood Tfh cells in SLE. OX40 signals promoted naive and memory CD4(+) Txa0cells to express multiple Tfh cell molecules and were sufficient to induce them to become functional B cell helpers. Immune complexes containing RNA induced OX40L expression on myeloid APCs via TLR7 activation. Our study provides a rationale to target the OX40L-OX40 axis as a therapeutic modality for SLE.

Tocilizumab Treatment Decreases Circulating Myeloid Dendritic Cells and Monocytes, 2 Components of the Myeloid Lineage

Objective. Interleukin 6 (IL-6) and tumor necrosis factor-α (TNF-α) are proinflammatory cytokines involved in inflammatory response. Effective TNF-α blocker treatment is associated with an increase in circulating myeloid dendritic cells (mDC), suggesting their release from inflamed synovium. Currently, in vivo effects of IL-6 inhibition on DC are unknown. We monitored the changes in circulating mDC and plasmacytoid DC (pDC) during tocilizumab (TCZ) therapy in patients with rheumatoid arthritis (RA). Methods. DC subset levels were evaluated by flow cytometry in patients with RA (n = 43) and in healthy volunteers (n = 20). In patients with RA, these levels were measured before and during TCZ therapy (8 mg/kg every 4 weeks). Response to TCZ therapy was evaluated at 12 weeks. Statistical analysis was based on Mann-Whitney U tests or Wilcoxon signed-rank tests. Results. At baseline, patients with active RA were characterized by a significantly lower level of circulating mDC and pDC compared to healthy donors. However, this difference did not correlate with any disease activity score. TCZ-treated patients who met the European League Against Rheumatism (EULAR) improvement criteria at Week 12 had significant reductions in mDC and monocyte levels as compared with EULAR nonresponders. Levels of pDC, CD4+ T cells, and CD8+ T cells remained stable during the TCZ courses, regardless of treatment response. Conclusion. Our study reveals an unexpected reduction of circulating mDC and monocytes in patients with RA in response to TCZ therapy. In accord with reports on neutrophils and platelets decreasing during TCZ therapy, our data suggest an effect of IL-6 inhibition on cells from myeloid lineage.

Potential Role of Mycoplasma hominis in Interleukin (IL)–17–Producing CD4+ T-Cell Generation Via Induction of IL-23 Secretion by Human Dendritic Cells

BACKGROUNDnMycoplasma hominis, a human urogenital pathogen, is involved in genital and extragenital infections and arthritis, particularly in immunocompromised patients. The interleukin (IL) 23/T helper (Th) 17 axis is associated with inflammatory and autoimmune diseases. The aim of this study was to assess the IL-23 response to M. hominis in human dendritic cells (DCs) and the CD4(+) T-cell differentiation in response to M. hominis-infected DCs.nnnMETHODSnHuman monocyte-derived DCs were cultured with phosphate-buffered saline, lipopolysaccharide, or M. hominis PG21. Cocultures with heterologous T cells were performed. Extracts from M. hominis were separated and incubated with DCs. Isolates from different clinical syndromes were tested.nnnRESULTSnM. hominis induced the maturation of human DCs with predominant IL-23 secretion in a Toll-like receptor 2-dependent manner. The in vitro immunomodulatory capacity of M. hominis was contained in a lipoprotein-enriched fraction from the mycoplasma. M. hominis-activated DCs induced IL-17-producing CD4(+) T cells. Interestingly, clinical isolates differed in their ability to promote IL-23 secretion by DCs.nnnCONCLUSIONSnTaken together, our findings demonstrate a major role for the IL-23/Th17 axis in the defense against M. hominis and indicate a potential role for these bacteria in inflammatory and autoimmune diseases.

Potential role of the soluble form of CD40 in deficient immunological function of dialysis patients: new findings of its amelioration using polymethylmethacrylate (PMMA) membrane.

Even though numerous studies have helped to better delineate abnormalities of either innate or adaptive immune system in end-stage renal disease (ESRD) patients, understanding immune dysfunctions in ESRD patients remains a very complex puzzle with missing pieces. In this context, we showed that the soluble form of CD40 (sCD40) is elevated in ESRD patients and is associated with a lack of response to hepatitis B vaccination. Interestingly, although most dialysis membranes are unable to clear sCD40, we demonstrated that polymethylmethacrylate (PMMA) BK-F membranes (Toray Medical Company, Japan) allow a dramatic diminution of the molecule. We took advantage of this observation to address the question of the potential usefulness of PMMA membrane (BK-F series) in the improvement of humoral immune response of ESRD patients. We, thus, present our recent data highlighting the potential role of BK-F membrane in the improvement of hepatitis B vaccination of ESRD patients who failed to mount a protective immune response despite one or more well-conducted anterior vaccination. Taken as a whole, our findings reinforced the concept of seeing dialysis membranes not just as a simple diffusive device but as a tool to tailor dialysis procedure to improve the global quality of life of ESRD patients. This opens a wide area of investigation, notably for the management of immunological dysfunction of ESRD patients.

Septic shock sera containing circulating histones induce dendritic cell-regulated necrosis in fatal septic shock patients.

Objectives:Innate immune system alterations, including dendritic cell loss, have been reproducibly observed in patients with septic shock and correlated to adverse outcomes or nosocomial infections. The goal of this study is to better understand the mechanisms behind this observation in order to better assess septic shock pathogenesis. Design:Prospective, controlled experimental study. Setting:Research laboratory at an academic medical center. Subjects:The study enrolled 71 patients, 49 with septic shock and 22 with cardiogenic shock. Seventeen healthy controls served as reference. In vitro monocyte-derived dendritic cells were generated from healthy volunteers. Interventions:Sera were assessed for their ability to promote in vitro dendritic cell death through flow cytometry detection in each group of patients. The percentage of apoptotic or necrotic dendritic cells was evaluated by annexin-V and propidium iodide staining. Measurements and Main Results:We observed that only patients with septic shock and not patients with pure cardiogenic shock were characterized by a rapid and profound loss of circulating dendritic cells. In vitro analysis revealed that sera from patients with septic shock induced higher dendritic cell death compared to normal sera or cardiogenic shock (p < 0.005). Sera from surviving patients induced dendritic cell death through a caspase-dependent apoptotic pathway, whereas sera from nonsurviving patients induced dendritic cell–regulated necrosis. Dendritic cell necrosis was not due to necroptosis but was dependent of the presence of circulating histone. The toxicity of histones toward dendritic cell could be prevented by recombinant human activated protein C. Finally, we observed a direct correlation between the levels of circulating histones in patients and the ability of the sera to promote dendritic cell–regulated necrosis. Conclusions:The study demonstrates a differential mechanism of dendritic cell death in patients with septic shock that is dependent on the severity of the disease.

Platelets Induce Thymic Stromal Lymphopoietin Production by Endothelial Cells: Contribution to Fibrosis in Human Systemic Sclerosis.

To investigate the relationship between vascular damage and fibrosis in systemic sclerosis (SSc) by testing the hypothesis that platelets contribute to skin fibrosis via the activation of human dermal microvascular endothelial cells (HDMECs) and subsequent production of profibrotic mediators.

Platelets induce thymic stromal lymphopoietin production by endothelial cells: Contribution to human systemic sclerosis fibrosis

To investigate the relationship between vascular damage and fibrosis in systemic sclerosis (SSc) by testing the hypothesis that platelets contribute to skin fibrosis via the activation of human dermal microvascular endothelial cells (HDMECs) and subsequent production of profibrotic mediators.

Distal Angiopathy and Atypical Hemolytic Uremic Syndrome: Clinical and Functional Properties of an Anti–Factor H IgAλ Antibody

Abnormal regulation of the alternative pathway of the complement system is a well-described trigger of microangiopathy leading to atypical hemolytic uremic syndrome (aHUS). However, the involvement of complement dysregulation in distal angiopathy has not been reported in adults. We describe the clinical course of a patient with severe distal angiopathy (amputation of all fingers and toes) followed 3 years later by aHUS with end-stage renal disease. This course was attributed to a circulating monoclonal immunoglobulin A λ light chain (IgAλ) with unusual properties: it bound complement factor H (CFH) and impaired CFH-glycosaminoglycan interaction and cell-surface protection. Local complement activation with distal angiopathy and microvascular injury was suggested by deposition of IgA, C4d, and C5b-9 in limb and preglomerular arteries. We therefore postulated that the monoclonal IgAλ inhibited activity of endothelial cell-bound CFH, which led to local activation of complement, vasoconstriction (distal angiopathy), and aHUS. While the patient was dependent on dialysis and plasma exchange, treatment with the anti-C5 antibody eculizumab induced remission of distal angiopathy and aHUS. During eculizumab treatment, kidney transplantation was performed. The patient had normal kidney function at the 3-year follow-up. We suggest that the association of distal angiopathy and aHUS in this patient is clearly linked to anti-CFH properties of the monoclonal IgAλ.

Comparison of ADVIA Centaur® and Pharmacia UniCAP® tests in the diagnosis of food allergy in children with atopic dermatitis

In a study comprising 63 children diagnosed with atopic dermatitis, the results of the ADVIA Centaur system was compared with the results obtained with the Pharmacia UniCAP100 system, which has been widely considered as a reference method for seric specific IgE (sIgE) measurements. The individual immunization against the most common food allergens [egg (f1), cow milk (f2), cod (f3), wheat (f4), peanut (f13) and soy bean (f14)] was determined by in vitro serum IgE testing and skin prick test (SPT). The comparison of the sIgE titers revealed a good concordance between the Centaur and the UniCAP tests for f1, f3, and f13 (94 %, 91 %, and 96 % respectively). However, the concordance was lower for f2, f4, and f14 (76 %, 77 %, and 77 % respectively) because of discrepancies between the two techniques. When compared with SPT and clinical diagnosis, on the 40 discordant cases found between the Centaur and the UniCAP, the Centaur showed concordance with the patients food reaction and SPT in 34/40 cases, and UniCAP in only 6/40 cases. Accordingly, the Centaur test displayed a statistically significantly better performance on specificity and concordance with SPT for f2, f4, and f14 (concordance/specificityu2003=u200370%/71%, 76%/75% and 90%/88% respectively), than the CAP test (49%/54%, 51%/52% and 67%/65% respectively).

Association of the Presence of Anti-Carbamylated Protein Antibodies in Early Arthritis With a Poorer Clinical and Radiologic Outcome: Data From the French ESPOIR Cohort

To assess the prevalence of anti–carbamylated protein (anti‐CarP) antibodies in a French cohort of patients with early arthritis and to investigate their association with clinical features, final diagnosis, prognosis, and comorbidities.