Interplay between Humoral and CLA+ T Cell Response against Candida albicans in Psoriasis.

Candida albicans (CA) infections have been associated with psoriasis onset or disease flares. However, the integrated immune response against this fungus is still poorly characterized in psoriasis. We studied specific immunoglobulins in plasma and the CA response in cocultures of circulating memory CD45RA- cutaneous lymphocyte antigen (CLA)+/- T cell with autologous epidermal cells from plaque and guttate psoriasis patients (cohort 1, n = 52), and also healthy individuals (n = 17). A complete proteomic profile was also evaluated in plaque psoriasis patients (cohort 2, n = 114) regarding their anti-CA IgA levels. Increased anti-CA IgA and IgG levels are present in the plasma from plaque but not guttate psoriasis compared to healthy controls. CA cellular response is confined to CLA+ T cells and is primarily Th17. The levels of anti-CA IgA are directly associated with CLA+ Th17 response in plaque psoriasis. Proteomic analysis revealed distinct profiles in psoriasis patients with high anti-CA IgA. C-C motif chemokine ligand 18, chitinase-3-like protein 1 and azurocidin were significantly elevated in the plasma from plaque psoriasis patients with high anti-CA levels and severe disease. Our results indicate a mechanism by which Candida albicans exposure can trigger a clinically relevant IL-17 response in psoriasis. Assessing anti-CA IgA levels may be useful in order to evaluate chronic psoriasis patients.

IL-15 and IL-23 synergize to trigger Th17 response by CLA+ T cells in psoriasis.

IL-15 has emerged as a potentially relevant target in the IL-17 response in psoriasis. However, its mechanism is poorly characterized in humans. IL-15 and IL-23 are constitutively expressed in the psoriatic lesion. Also, IL-15 is considered a susceptibility-associated gene in psoriasis, as are IL-23R, and HLACW6. Here, we studied the effect of IL-15 and IL-23 stimulation on the cytokine response of CLA+/CLA- T cells from 9 psoriasis patients and 3 healthy control subjects. To this end, CLA + and CLA- T cells from blood samples were cultured with epidermal cells from skin biopsies and treated with IL-15 and IL-23. After five days of culture, cytokines in supernatant were measured by ELISA or fluorescent bead-based immunoassay. There was a statistically significant increase in IL-17F and IL-17A production (P < .001) in cocultures of psoriasis skin-homing CLA + T cells with epidermal cells when stimulated with IL-15 and IL-23, but this effect was not observed in the cells of healthy controls. Interestingly, this response was reduced by around 50 to 80% by blocking HLA class I and II molecules. Our results point to the synergic action of IL-15 and IL-23 selectively for CLA + cells in psoriasis, leading to the induction of Th17 cell-related cytokines.

Streptococcus pyogenes-induced cutaneous lymphocyte antigen-positive T cell-dependent epidermal cell activation triggers TH17 responses in patients with guttate psoriasis.

BACKGROUND: Guttate psoriasis (GP) is characterized by acute onset of small, rounded psoriatic lesions. Although this particular phenotype of psoriasis is usually associated with streptococcal throat infections and mainly occurs in HLA-Cw6(+) patients, the specific immunologic response to this innate stimulus that causes these skin lesions is poorly understood. OBJECTIVE: This study aims to elucidate how key cellular elements of patients with GP respond to Streptococcus pyogenes and whether this initial immune response is favored by the genetic and environmental background of these patients. METHODS: Circulating memory T cells and autologous epidermal cells from samples from either patients with GP (n = 14) or healthy control subjects (n = 6) were cocultured ex vivo in the presence of an S pyogenes extract. Levels of the psoriasis-associated cytokines IL-17A, IL-17F, IFN-γ, TNF-α, IL-6, and IL-8 were determined. The expression of several genes with increased (DEFB4, S100A7, LCN2, IL36G, IL8, CXCL9, CXCL10, and CXCL11) or decreased (FLG and LOR) transcripts in psoriatic lesions was examined in keratinocytes treated with coculture supernatants. RESULTS: When skin-homing effector memory cutaneous lymphocyte antigen-positive T cells were used in cocultures, a TH17-dominant response was observed, as reflected by the higher amounts of IL-17A and IL-17F than IFN-γ. Moreover, a higher TH17 response was observed in cells isolated from patients with flares associated with a streptococcal tonsillitis and with the HLA-Cw6 allele (cohort 1). In addition, in normal keratinocytes the supernatants from these cocultures induced an increase in IL-17-associated genes, such as DEFB4, S100A7, LCN2, IL36G, and IL8 but a decrease in FLG and LOR, thereby confirming the role of activated TH17 cells. CONCLUSION: This study reveals a dominant TH17 response of cutaneous lymphocyte antigen-positive T cells activated by epidermal cells and S pyogenes in patients with GP.

Memory T Cell Subpopulations as Early Predictors of Remission to Vedolizumab in Ulcerative Colitis.

Background: Vedolizumab is a humanized monoclonal antibody targeting the α4ß7 integrin used for the treatment of ulcerative colitis. Few biomarkers related to vedolizumab response have been identified. The aim of this work was to assess whether baseline circulating CD4+ and CD8+ memory T-lymphocyte subpopulations could help to identify patients with response to vedolizumab treatment in ulcerative colitis. Methods: Prospective pilot study in 15 patients with active ulcerative colitis and previous failure to anti-TNFα starting vedolizumab treatment. Peripheral blood samples were obtained before the first dose of vedolizumab and at week 6 and 14 of treatment. Clinical remission was defined as a Mayo Clinic partial score of ≤2 points without any concomitant dose of steroids. Biochemical remission or endoscopic improvement was defined as fecal calprotectin <250 mcg/g or Mayo endoscopic subscore ≤1. Results: At week 14, nine patients achieved clinical remission and eight patients achieved biochemical remission or endoscopic improvement. Patients in clinical remission presented higher baseline CD8 α4ß7 + memory T cells concentration when compared with patients with no remission. In addition, patients with biochemical remission or endoscopic improvement at week 14 presented higher baseline concentration of CD8 α4ß7 + memory T cells. No differences were identified according to flare severity, extent of disease or type of anti-TNFα failure. There were no significant differences regarding changes in T cell subsets during vedolizumab induction. Conclusion: CD8+ α4ß7 + memory T cells before starting vedolizumab therapy could be an early predictor of remission in ulcerative colitis patients and therefore help to select a subset of responders.

Specific IgA and CLA+ T-Cell IL-17 Response to Streptococcus pyogenes in Psoriasis.

Streptococcus pyogenes tonsillar infection is well known to trigger and exacerbate psoriasis lesions in both guttate and plaque forms of the disease. Although mucosal and cutaneous tissues are closely involved in psoriasis pathology, the interaction between their specific immune responses has not been deeply explored. This work aims to address and characterize the presence of humoral responses against S. pyogenes in patients with psoriasis and its putative association with cytokine responses detected in vitro in our psoriasis ex vivo model, based on the coculture of cutaneous lymphocyte-associated antigen+/- T cells with autologous epidermal cells. Patients with psoriasis presented increased IgA response to S. pyogenes when compared with control subjects. In patients with plaque psoriasis, despite being negative for anti-streptolysin O antibody titer, IgA plasma levels against S. pyogenes correlated with cutaneous lymphocyte-associated antigen+ T-cell-dependent IL-17F response in vitro. No association is observed for IgG levels in plaque psoriasis. Similar association is observed for IgA anti-S. pyogenes extract and IL-17A in patients with guttate psoriasis. We propose S. pyogenes-specific IgA as a potential new perspective for better understanding the role of S. pyogenes in psoriasis development.

CLA+ T Cell Response to Microbes in Psoriasis.

Streptococcus pyogenes throat infection is a clinically relevant trigger of both guttate and chronic plaque psoriasis, and it provides an ideal context in which to study the pathogenesis of these diseases using an antigen-dependent approach. Circulating cutaneous lymphocyte-associated antigen (CLA) positive (+) memory T cells are a subset of peripheral lymphocytes whose phenotype and function are related to immunological mechanisms in the skin. These cells are considered peripheral biomarkers of T-cell-mediated skin diseases. The coculture of autologous epidermal cells with CLA+ T cells from psoriasis patients activated by S. pyogenes allows the reproduction of the ex vivo initial molecular events that occur during psoriatic lesion formation. With cooperation of autologous epidermal cells, S. pyogenes selectively activates CLA+ T cells both in guttate and plaque psoriasis, inducing key mediators, including an IL-17 response. Here, we explore potential new mechanisms of psoriasis development including the influence of HLA-Cw6 on S. pyogenes CLA+ T cell activation in guttate psoriasis, the relevance of IL-9 on microbe induced IL-17 response in guttate and plaque psoriasis, and novel effector functions of Candida albicans. This review will summarize recent knowledge of psoriatic mechanisms elicited by microbes that have been studied through an innovative translational perspective based on CLA+ T cell-mediated cutaneous immune response.

Microbe-Dependent Induction of IL-9 by CLA+ T Cells in Psoriasis and Relationship with IL-17A.

IL-9 is present in psoriatic lesions and is produced by lymphocytes. However, it is not known whether this cytokine is induced by relevant pathogenic triggers of psoriasis, such as Streptococcus pyogenes. Here we addressed the production of IL-9 in response to various pathogens in a psoriatic ex vivo model. Extracts of S. pyogenes and Candida albicans triggered the production of IL-9 and also IL-17A and IFN-γ. This induction was dependent on the interaction between CLA+ T cells and epidermal cells. Neutralization of IL-9 reduced S. pyogenes-induced IL-17A production by CLA+ T cells but had no effect on IFN-γ production. Also, IL-9 increased the survival of circulating psoriatic CLA+ T cells. Co-cultures from patients with guttate or plaque psoriasis with S. pyogenes produced similar amounts of IL-9. High cytokine responses in streptococcal-driven guttate patients paralleled peaks in Psoriasis Area Severity Index and anti-streptolysin O levels. Our results confirm that IL-9 promotes inflammation in psoriasis by up-regulating IL-17A production and support the clinical association of the immune response by streptococcal-sensitized CLA+ T cells with this cytokine, especially in guttate psoriasis.

MCPIP1 RNase Is Aberrantly Distributed in Psoriatic Epidermis and Rapidly Induced by IL-17A.

ZC3H12A, which encodes the RNase monocyte chemotactic protein-induced protein 1 (MCPIP1), is up-regulated in psoriatic skin and reduced to normal levels after clinical treatments with anti-IL-17A/IL-17R neutralizing antibodies. In IL-17A-stimulated keratinocytes, MCPIP1 is rapidly increased at the transcript and protein levels. Also, IL-17A was found to be the main inducer of ZC3H12A expression in keratinocytes treated with supernatants derived from a Streptococcus pyogenes-activated psoriatic ex vivo model based on the co-culture of psoriatic cutaneous lymphocyte-associated antigen (CLA(+)) T cells and lesional epidermal cells. Moreover, MCPIP1 was aberrantly distributed in the suprabasal layers of psoriatic epidermis. In psoriatic samples, IL-17A-stimulated epidermal cell suspensions showed an increased MCPIP1 expression, especially in the mid-differentiated cellular compartment. The knockdown of ZC3H12A showed that this RNase participates in the regulation of the mRNAs present in suprabasal differentiated keratinocytes. Furthermore, JAK/STAT3 inhibition prevented the IL-17A-dependent induction of MCPIP1. In the mouse model of imiquimod-induced psoriasis, Zc3h12a expression was abrogated in Il17ra(-/-) mice. These results support the notion that IL-17A-mediated induction of MCPIP1 is involved in the regulation of local altered gene expression in suprabasal epidermal layers in psoriasis.