Langerin+ Dermal DC, but not Langerhans cells, are required for effective CD8 mediated immune responses after skin scarification with Vaccinia Virus (VACV)

Skin scarification (s.s.) with Vaccinia virus (VACV) is essential for generation of an optimal protective T cell memory immune response. Dendritic Cells (DC), which are professional antigen presenting cells, are required for naïve T cell priming and activation. At least three subsets of skin resident DC have been identified: Langerhans Cells (LC), Dermal Langerin+ DC (Lang+dDC) and Dermal Langerin− DC (Lang−dDC). Using Langerin-diphtheria toxin receptor mice and established mouse model of VACV delivered by s.s., we demonstrated that Lang+dDC, but not LC, are absolutely required for the induction of a rapid and robust antigen-specific CD8+ T cell response after s.s. with VACV. The depletion of Lang+dDC led to a significant delay in the priming and proliferation of antigen-specific CD8+ T cells. Moreover CD8+ T cells generated after VACV s.s. in the absence of Lang+dDC lacked effector cytotoxic functions both in vitro and in vivo. While s.s.-immunized WT and LC depleted mice controlled the progression of OVA257–264 expressing T cell lymphoma EG7 (injected intradermally), the depletion of Lang+dDC led to rapid lymphoma progression and mortality. These data indicate that of all skin DC subsets, Lang+dDC the most critical for the generation of robust CD8+ T cell immunity after s.s. with VACV

Modulation of interferon-[alpha] secretion by activated platelets in systemic lupus erythematosus.

Type I interferons play a key role in systemic lupus erythematosus (SLE) pathogenesis as an "IFN signature" is found in the majority of patients with active SLE. Immune complexes are internalized by plasmacytoid dendritic cells (DC) via Fc-[gamma] ReceptorIIA, reach the endosomal compartment and activate IFN-[alpha] secretion through TLR7/9-dependent pathways. Naturally occurring differences in expression of the TLR7/9 gene as well as factors that modulate TLR7/9 expression, including CD154 could therefore contribute to SLE pathogenesis. Although its origin is not elucidated CD154 is hyperexpressed in SLE patients, and is important for the differentiation of autoantibody-secreting cells. We hypothesized that platelets which are an abundant source of CD154, and which can mediate proinflammatory effects could be an actor involved in SLE pathogenesis. Platelets from SLE patients are activated _in vivo_ by circulating immune complexes which are abundant in SLE sera, via a CD32-dependent mechanism. Activated platelets formed aggregates with antigen-presenting cells in SLE patients and enhanced interferon-[alpha] secretion induced by immune-complexes stimulated plasmacytoid DCs. Finally, _in vivo_ depletion of platelets and megakaryocytes in NZBxNZW(F1) lupus prone mice improved all parameters assessing disease activity, whereas transfusion of activated platelets worsened the disease course. Altogether, these data identify platelets as a mediator of SLE pathogenesis and a new therapeutical target

Segmentation 3D d'hologrammes numériques de particules par palpage morphologique : application à l'analyse d'un jet diesel haute-pression

Dans cette article, nous nous intéressons à l'holographie numérique pour l'étude d'un champ volumique de particules. L'holographie numérique offre de nouvelles possibilités par rapport à l'holographie sur plaque photosensible, notamment du point de vue de sa facilité de mise en oeuvre. L'hologramme d'un champ de particules enregistré sur un capteur matriciel, est restitué numériquement plan par plan afin de pouvoir localiser les particules dans le volume d'étude. Nous introduisons pour cela une méthode de détection des particules par palpage morphologique. Nous avons appliqué cette technique à l'obtention d'un champ tridimensionnel de particules en volume, et nous présentons les résultats pour un jet issu d'un injecteur diesel haute-pression

Efficacy and safety of lebrikizumab in moderate-to-severe atopic dermatitis: results from two phase III, randomized, double-blinded, placebo-controlled trials

Lebrikizumab, a high-affinity IgG-4 monoclonal antibody targeting interleukin (IL)-13, selectively prevents the formation of the IL-13Ra1/IL-4Ra heterodimer receptor signalling complex. Lebrikizumab demonstrated rapid, dose-dependent efficacy and an acceptable safety profile in patients with moderate-to-severe atopic dermatitis (AD) in a phase IIb trial (NCT03443024). Here, we report 16-week efficacy and safety outcomes of lebrikizumab monotherapy in patients with AD from two ongoing 52-week, randomized, double-blinded, placebo-controlled phase III trials – ADvocate1 (NCT04146363) and ADvocate2 (NCT04178967). Eligible patients with moderate-to-severe AD [adults and adolescents (12–17 years of age, weighing ≥40 kg)] were randomized 2: 1 to subcutaneous lebrikizumab 250 mg or placebo every 2 weeks. Efficacy analyses included proportions of patients achieving Investigator’s Global Assessment (IGA) 0/1, Eczema Area and Severity Index (EASI)-75 and Pruritus Numerical Rating Scale (NRS) ≥ 4-point improvement from baseline (P ≥ 4) at week 16. Nonefficacy-related missing data were imputed by multiple imputation. In ADvocate1, proportions of patients treated with lebrikizumab 250 mg (n = 283) and placebo (n = 141) achieving IGA 0/1 at week 16 were 43.0% and 12.8% (P \u3c 0.001); EASI-75 responses were 59.3% and 16.4% (P \u3c 0.001); P ≥ 4 proportions were 46.3% and 12.7% (P \u3c 0.001), respectively. In ADvocate2 (lebrikizumab, n = 281; placebo, n = 146), corresponding proportions for IGA 0/1 were 33.1% and 10.9% (P \u3c 0.001); EASI-75 responses were 50.8% and 18.2% (P \u3c 0.001); P ≥ 4 proportions were 38.3% and 11.3% (P \u3c 0.001), respectively. The percentage of patients reporting ≥1 TEAE was comparable in ADvocate1 (lebrikizumab, 45.4%; placebo, 51.1%) and ADvocate2 (lebrikizumab 53.0%; placebo 66.2%). Data from two ongoing pivotal phase III trials suggest that lebrikizumab 250 mg Q2W provides an efficacious treatment option with an acceptable safety profile for patients with moderate-to-severe AD

Antitumour necrosis factor-α therapy for hidradenitis suppurativa: results from a national cohort study between 2000 and 2013

International audienceHidradenitis suppurativa (HS) is a frequent chronic inflammatory skin disease typically characterized by recurrent painful, deep inflammatory nodules of the axillary, breast, groin and gluteal areas. European recommendations are mainly based on expert opinion. Drug treatments are heterogenous (e.g., antibiotics, corticosteroids, retinoids) and lack consensus among expert centres. The most severe disease forms or those failing to respond to conventional drugs may be associated with worsened functional prognosis. Anti-tumor necrosis factor α (anti-TNFα) drugs have been prescribed in these cases. The results of randomized controlled trials (RCTs) are discordant. Three RCTs concluded to the efficacy of adalimumab (ADA), and two others did not detect any difference between infliximab (IFX) or etanercept (ETA) and placebo. Finally, data from the literature and reported experiences do not conclude on the efficacy of anti-TNFα drugs for HS. This article is protected by copyright. All rights reserve

CD95 recruits PLCγ1 to trigger a calcium response promoting Th17 accumulation in inflamed organs of lupus mice

CD95 ligand (CD95L) is expressed by immune cells and triggers apoptotic death. Metalloprotease-cleaved CD95L (cl-CD95L) is released into the bloodstream but does not trigger apoptotic signaling. Hence, the pathophysiological role of cl-CD95L remains unclear. We observed that skin-derived endothelial cells from systemic lupus erythematosus (SLE) patients expressed CD95L, and that after cleavage, cl-CD95L promoted T helper 17 (Th17) lymphocyte transmigration across the endothelial barrier at the expense of T regulatory cells. T cell migration relied on a direct interaction between the CD95 domain called calcium-inducing domain (CID) and the Src homology 3 domain of phospholipase Cγ1. Th17 cells stimulated with cl-CD95L produced sphingosine-1-phosphate (S1P), which promoted endothelial transmigration by activating the S1P receptor 3. We generated a cell-penetrating CID peptide that prevented Th17 cell transmigration and alleviated clinical symptoms in lupus mice. Therefore, neutralizing the CD95 non-apoptotic signaling pathway may be attractive therapeutic approach for SLE treatment