Cellular sources of IL-23 and IL-17A driving skin inflammation in psoriasis remain unclear. Using high-dimensional unsupervised flow cytometry analysis, mononuclear phagocytes and T cells were ...examined in the same lesions of patients before and during guselkumab (IL-23p19 blocker) or secukinumab (IL-17A blocker) treatment. Among CD11c+HLA-DR+ mononuclear phagocytes, CD64brightCD163−CD14brightCD1c−CD1a‒ inflammatory monocyte‒like cells were the predominant IL-23–producing cells and, together with CD64−CD163−CD14−IL-23p19−TNF-α+ inflammatory dendritic cell‒like cells, were increased in lesional compared with those in nonlesional skin taken from the same patient. Within T cells, CD8+CD49a+ and/or CD103+ tissue-resident memory T cells, CD4+CD25+FoxP3+ regulatory T cells, and CD4+CD49a−CD103− T cells were increased. Moreover, CD4+CD49a−CD103− T cells and the relatively rare CD8+ memory T cells equally contributed to IL-17A production. Both treatments decreased the frequencies of inflammatory monocyte‒like, inflammatory dendritic cell‒like, and CD4+CD49a−CD103− T cells. In contrast, guselkumab reduced memory T cells while maintaining regulatory T cells and vice versa for secukinumab. Neither drug modified the frequencies of IL-17A+IL‒17F+/– CD4+ or CD8+ T cells. This study reveals the identity of the major IL-23+ mononuclear phagocyte and IL-17+ T-cell subsets in psoriatic skin lesions and paves the way for a better understanding of the mode of action of drugs targeting the IL-23/IL-17A pathway in psoriasis.
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Viral respiratory tract infections are the main causative agents of the onset of infection-induced asthma and asthma exacerbations that remain mechanistically unexplained. Here we found that ...deficiency in signaling via type I interferon receptor led to deregulated activation of group 2 innate lymphoid cells (ILC2 cells) and infection-associated type 2 immunopathology. Type I interferons directly and negatively regulated mouse and human ILC2 cells in a manner dependent on the transcriptional activator ISGF3 that led to altered cytokine production, cell proliferation and increased cell death. In addition, interferon-γ (IFN-γ) and interleukin 27 (IL-27) altered ILC2 function dependent on the transcription factor STAT1. These results demonstrate that type I and type II interferons, together with IL-27, regulate ILC2 cells to restrict type 2 immunopathology.
Background
The potential benefit of inducing delayed‐type hypersensitivity (DTH) reaction in healthy volunteers (HVs) as experimental models to study skin inflammatory disorders was recently reported ...using bulk molecular technologies. Immunophenotype of skin T cells, including cellular source of Type 1, 2, and 3 cytokines, in a local DTH reaction and their modulation by oral drugs remain to be investigated.
Method
Purified protein derivative (PPD), nickel, diphencyprone (DPCP), or house dust mite (HDM) was administered as sensitizer to 40 HVs. In addition, 20 HVs were randomized to receive oral prednisone or placebo before DPCP challenge. We characterized the immunophenotype and cytokine profile of CD3+ T cell infiltrate, and examined the modulation by oral prednisone at single‐cell level using multiparameter flow cytometry and unsupervised analysis.
Results
PPD was biased toward a Th1 and Tc1 response, and HDM a Th2/Th17 and Tc2. Nickel and DPCP displayed a mixed Th1/Th2/Th17 and Tc1 response. CD4+CD25+FoxP3+ regulatory T cells (Tregs), the minor CD4+CD25+FoxP3−ICOS+PD‐1+ (activated PD‐1+ Th), and CD103+ tissue resident memory (TRM) cells were detected in all groups. DPCP uniquely elicited rare CD8+CD103+CD25+RoRγt+PD‐1+ICOS+IFNγ+ T cells (activated CD8+IFNγ+PD‐1+ TRM). Oral prednisone decreased frequencies of activated PD‐1+ Th and CD8+IFNγ+PD‐1+ TRM subsets relative to placebo in DPCP reaction. The latter was positively correlated with improvement of clinical parameters with prednisone.
Conclusion
DTH and skin CD3+ T cell profiles elicited by common sensitizers can be modulated by oral drugs. Corticosteroids reduce the frequencies of activated PD‐1+ Th and CD8+IFNγ+PD‐1+ TRM cells after DPCP exposure.
PPD predominantly elicited Th1 and Tc1 responses, HDM triggered Th2 and Th17 responses, while nickel induced a broad range of cytokine responses but at lower frequencies than DPCP during a DTH reaction. DPCP induced the broadest skin Th1/Th2/Th17, Tc1, Treg, and TRM responses. Oral prednisone decreased SHR diameter, ICDRG score, and skin CD25+PD‐1+ Th and CD25+CD8+IFNγ+PD‐1+ TRM post‐DPCP. Abbreviations: DTH, delayed‐type hypersensitivity; DPCP, diphencyprone; HDM, house dust mite; ICDRG, international contact dermatitis research group; PPD, purified protein derivative; SHR, secondary hypersensitivity reaction; Th, T helper cells; Treg, regulatory T cell; TRM, tissue‐resident memory; UMAP, Uniform Manifold Approximation and Projection
Platelets can be activated by IgE and are therefore involved in IgE-mediated effector mechanisms against parasites and in allergic disorders. Here we show that, besides the low-affinity IgE receptor ...(Fc epsilon RII/CD23), platelets express the high-affinity receptor for IgE (Fc epsilon RI). Flow cytometry analysis revealed the existence of surface Fc epsilon RI on platelets with a large heterogeneity among individual donors, and a low proportion of platelets co-expressing Fc epsilon RI and FC epsilon RII/CD23. Northern hybridization and reverse transcription polymerase chain reaction confirmed the presence of mRNA encoding the alpha, beta and gamma chains of Fc epsilon RI in platelets and in their megakaryocytic precursors. Cross-linking of Fc epsilon RI with monoclonal antibody (mAb) to alpha chain using either the whole molecule or F(ab')2 triggered platelet cytotoxicity for Schistosoma mansoni larvae. Anti-Fc epsilon RII/CD23 mAb significantly inhibited IgE- or Fc epsilon RI-mediated cytotoxicity, indicating down-regulatory effects of Fc epsilon RII/CD23 on Fc epsilon RI-dependent functions. These results demonstrate functional properties for Fc epsilon RI on platelets and indicate unsuspected interactions between the low- and the high-affinity IgE receptors.
Patients with systemic sclerosis (SSc) display altered intestinal microbiota. However, the influence of intestinal dysbiosis on the development of experimental SSc remains unknown. Topoisomerase I ...peptide-loaded dendritic cell immunization induces SSc-like disease, with progressive skin and lung fibrosis. Breeders were given streptomycin and pups continued to receive antibiotic (ATB) until endpoint (lifelongATB). Alternately, ATB was withdrawn (earlyATB) or initiated (adultATB) during adulthood. Topoisomerase I peptide-loaded dendritic cell (no ATB) immunization induced pronounced skin fibrosis, with increased matrix (Col1a1), profibrotic (Il13, Tweakr), and vascular function (Serpine1) gene expression. Remarkably, earlyATB exposure was sufficient to augment skin Col5a1 and Il13 expression, and inflammatory cell infiltration, which included IL-13+ cells, mononuclear phagocytes, and mast cells. Moreover, skin pathology exacerbation was also observed in lifelongATB and adultATB groups. Oral streptomycin administration induced intestinal dysbiosis, with exposure limited to early life (earlyATB) being sufficient to cause long-term modification of the microbiota and a shift toward increased Bacteroidetes/Firmicutes ratio. Finally, aggravated lung fibrosis and dysregulated pulmonary T-cell responses were observed in earlyATB and lifelongATB but not adultATB-exposed mice. Collectively, intestinal microbiota manipulation with streptomycin exacerbated pathology in two distinct sites, skin and lungs, with early life being a critical window to affect the course of SSc-like disease.
Mitochondrial metabolism is a tightly regulated process that plays a central role throughout the lifespan of hematopoietic cells. Herein, we analyze the consequences of the mitochondrial oxidative ...phosphorylation (OXPHOS)/metabolism disorder associated with the cell-specific hematopoietic ablation of apoptosis-inducing factor (AIF). AIF-null (AIF
) mice developed pancytopenia that was associated with hypocellular bone marrow (BM) and thymus atrophy. Although myeloid cells were relatively spared, the B-cell and erythroid lineages were altered with increased frequencies of precursor B cells, pro-erythroblasts I, and basophilic erythroblasts II. T-cell populations were dramatically reduced with a thymopoiesis blockade at a double negative (DN) immature state, with DN1 accumulation and delayed DN2/DN3 and DN3/DN4 transitions. In BM cells, the OXPHOS/metabolism dysfunction provoked by the loss of AIF was counterbalanced by the augmentation of the mitochondrial biogenesis and a shift towards anaerobic glycolysis. Nevertheless, in a caspase-independent process, the resulting excess of reactive oxygen species compromised the viability of the hematopoietic stem cells (HSC) and progenitors. This led to the progressive exhaustion of the HSC pool, a reduced capacity of the BM progenitors to differentiate into colonies in methylcellulose assays, and the absence of cell-autonomous HSC repopulating potential in vivo. In contrast to BM cells, AIF
thymocytes compensated for the OXPHOS breakdown by enhancing fatty acid β-oxidation. By over-expressing CPT1, ACADL and PDK4, three key enzymes facilitating fatty acid β-oxidation (e.g., palmitic acid assimilation), the AIF
thymocytes retrieved the ATP levels of the AIF
cells. As a consequence, it was possible to significantly reestablish AIF
thymopoiesis in vivo by feeding the animals with a high-fat diet complemented with an antioxidant. Overall, our data reveal that the mitochondrial signals regulated by AIF are critical to hematopoietic decision-making. Emerging as a link between mitochondrial metabolism and hematopoietic cell fate, AIF-mediated OXPHOS regulation represents a target for the development of new immunomodulatory therapeutics.
Human Slan DCs have been studied in patients with psoriasis, rheumatoid arthritis, cancer, and autoimmune diseases. In this study, we investigated the frequency, phenotype, and function of Slan DCs ...in blood, colon, as well as mLNs of patients with IBD. We first show that the frequency of circulating CD14(dull)Slan DCs was reduced in CD patients refractory to immunosuppressive drugs or TNF-α blockers relative to untreated CD, UC, and healthy subjects. In blood of CD patients, Slan DCs expressed CD172a, as detected by CD47 fusion protein binding, when compared with its lack of expression in control subjects. Next, we demonstrate that CD172a(+)Slan DCs that produced IL-1β and TNF-α accumulated in mLNs and colons of CD patients. The CD172a(+)Slan DCs up-regulated their expression of CD14 in CD tissues and the proinflammatory cytokines were produced in CD14(bright)CD172a(+)Slan DCs. By contrast, no difference was noted in the frequency of Slan DCs between inflamed, noninflamed colonic mucosa of UC patients and control, non-IBD donors. Finally, the percentage of cytokine-producing Slan DCs also augmented in response to TLR2 and NOD2 in in vitro stimulation in PBMCs of CD, but not UC, patients. In conclusion, we propose that proinflammatory CD14(bright)CD172a(+)Slan DCs are a distinguishing feature between CD and UC, as these cells accumulate uniquely in mLNs and colonic mucosa of CD patients. Thus, Slan DCs may contribute to CD immunopathogenesis.
In this study, Santos Susin and colleagues demonstrate that a serum-stable CD47 agonist peptide is highly effective at inducing apoptosis in chronic lymphocytic leukemia B-cells and mice.
Thymus-derived CD4+ CD25+ T regulatory cells (Tregs) are essential for the maintenance of self-tolerance. What critical factors and conditions are required for the extra-thymic development of Tregs ...remains an important question. In this study, we show that the anti-inflammatory extracellular matrix protein, thrombospondin-1, promoted the generation of human peripheral regulatory T cells through the ligation of one of its receptor, CD47. CD47 stimulation by mAb or a thrombospondin-1 peptide induced naive or memory CD4+ CD25- T cells to become suppressive. The latter expressed increased amounts of CTLA-4, OX40, GITR, and Foxp3 and inhibited autologous Th0, Th1, and Th2 cells. Their regulatory activity was contact dependent, TGF-beta independent, and partially circumvented by IL-2. This previously unknown mechanism to induce human peripheral Tregs in response to inflammation may participate to the limitation of collateral damage induced by exacerbated responses to self or foreign Ags and thus be relevant for therapeutic intervention in autoimmune diseases and transplantation.
Basophils are, together with mast cells, typical innate effector cells of allergen-induced IgE-dependent allergic diseases. Both cell types express the high-affinity receptor for IgE (FcεR1), release ...histamine, inflammatory mediators, and cytokines following FcεR1 cross-linking. Basophils are rare granulocytes in blood, lymphoid, and non-lymphoid tissues, and the difficulties to detect and isolate these cells has hampered the study of their biology and the understanding of their possible role in pathology. Furthermore, the existence of other FcεR1-expressing cells, including professional Ag-presenting dendritic cells, generated some controversy regarding the ability of basophils to express MHC Class II molecules, present Ag and drive naïve T cell differentiation into Th2 cells. The focus of this review is to present the recent advances on the interactions between basophils and peripheral blood and tissue memory Th1, Th2, and Th17 cells, as well as their potential role in IgE-independent non-allergic chronic inflammatory disorders, including human inflammatory bowel diseases. Basophils interactions with the innate players of IgE-dependent allergic inflammation, particularly innate lymphoid cells, will also be considered. The previously unrecognized function for basophils in skewing adaptive immune responses opens novel perspectives for the understanding of their contribution to the pathogenesis of inflammatory diseases.
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