Juana Gonzalez

Th17 cytokines interleukin (IL)-17 and IL-22 modulate distinct inflammatory and keratinocyte-response pathways

Background  Psoriasis vulgaris is an inflammatory skin disease mediated by Th1 and Th17 cytokines, yet the relative contribution of interferon (IFN)‐γ, interleukin (IL)‐17 and IL‐22 on disease pathogenesis is still unknown.

Psoriasis is characterized by accumulation of immunostimulatory and Th1/Th17 cell-polarizing myeloid dendritic cells.

Myeloid dermal dendritic cells (DCs) accumulate in chronically inflamed tissues such as psoriasis. The importance of these cells for psoriasis pathogenesis is suggested by comparative T-cell and DC-cell counts, where DCs outnumber T cells. We have previously identified CD11c(+)-blood dendritic cell antigen (BDCA)-1(+) cells as the main resident dermal DC population found in normal skin. We now show that psoriatic lesional skin has two populations of dermal DCs: (1) CD11c(+)BDCA-1(+) cells, which are phenotypically similar to those contained in normal skin and (2) CD11c(+)BDCA-1(-) cells, which are phenotypically immature and produce inflammatory cytokines. Although BDCA-1(+) DCs are not increased in number in psoriatic lesional skin compared with normal skin, BDCA-1(-) DCs are increased 30-fold. For functional studies, we FACS-sorted psoriatic dermal single-cell suspensions to isolate these two cutaneous DC populations, and cultured them as stimulators in an allogeneic mixed leukocyte reaction. Both BDCA-1(+) and BDCA-1(-) myeloid dermal DC populations induced T-cell proliferation, and polarized T cells to become T helper 1 (Th1) and T helper 17 (Th17) cells. In addition, psoriatic dermal DCs induced a population of activated T cells that simultaneously produced IL-17 and IFN-gamma, which was not induced by normal skin dermal DCs. As psoriasis is believed to be a mixed Th17/Th1 disease, it is possible that induction of these IL-17(+)IFN-gamma(+) cells is pathogenic. These cytokines, the T cells that produce them, and the inducing inflammatory DCs may all be important new therapeutic targets in psoriasis.

Human Langerhans cells induce distinct IL-22-producing CD4+ T cells lacking IL-17 production

IL-22 is a cytokine that acts mainly on epithelial cells. In the skin, it mediates keratinocyte proliferation and epidermal hyperplasia and is thought to play a central role in inflammatory diseases with marked epidermal acanthosis, such as psoriasis. Although IL-22 was initially considered a Th17 cytokine, increasing evidence suggests that T helper cells can produce IL-22 even without IL-17 expression. In addition, we have shown the existence of this unique IL-22-producing T cell in normal skin and in the skin of psoriasis and atopic dermatitis patients. In the present study, we investigated the ability of cutaneous resident dendritic cells (DCs) to differentiate IL-22-producing cells. Using FACS, we isolated Langerhans cells (LCs; HLA-DR+CD207+ cells) and dermal DCs (HLA-DRhiCD11c+BDCA-1+ cells) from normal human epidermis and dermis, respectively. Both LCs and dermal DCs significantly induced IL-22-producing CD4+ and CD8+ T cells from peripheral blood T cells and naive CD4+ T cells in mixed leukocyte reactions. LCs were more powerful in the induction of IL-22-producing cells than dermal DCs. Moreover, in vitro-generated LC-type DCs induced IL-22-producing cells more efficiently than monocyte-derived DCs. The induced IL-22 production was more correlated with IFN-γ than IL-17. Surprisingly, the majority of IL-22-producing cells induced by LCs and dermal DCs lacked the expression of IL-17, IFN-γ, and IL-4. Thus, LCs and dermal DCs preferentially induced helper T cells to produce only IL-22, possibly “Th22” cells. Our data indicate that cutaneous DCs, especially LCs, may control the generation of distinct IL-22 producing Th22 cells infiltrating into the skin.

Severe atopic dermatitis is characterized by selective expansion of circulating TH2/TC2 and TH22/TC22, but not TH17/TC17, cells within the skin-homing T-cell population

BACKGROUND Past studies of blood T-cell phenotyping in patients with atopic dermatitis (AD) have provided controversial results and were mostly performed before the identification of TH9, TH17, and TH22 T-cell populations in human subjects. OBJECTIVE We sought to quantify TH1, TH2, TH9, TH17, and TH22 T-cell populations and corresponding CD8(+) T-cell subsets in both cutaneous lymphocyte antigen (CLA)-positive and CLA(-) T-cell subsets in patients with AD and control subjects. METHODS We studied 42 adults with severe AD (mean SCORAD score, 65) and 25 healthy subjects using an 11-color flow cytometric antibody panel. Frequencies of IFN-γ-, IL-22-, IL-13-, IL-17-, and IL-9-producing CD4(+) and CD8(+) T cells were compared in CLA(-) and CLA(+) populations. RESULTS We measured increased TH2/TC2/IL-13(+) and TH22/TC22/IL-22(+) populations (P < .1) in patients with severe AD versus control subjects, with significant differences in CLA(+) T-cell numbers (P < .01). A significantly lower frequency of CLA(+) IFN-γ-producing cells was observed in patients with AD, with no significant differences in CLA(-) T-cell numbers. The CLA(+) TH1/TH2 and TC1/TC2 ratio was highly imbalanced in patients with AD (10 vs 3 [P = .005] and 19 vs 7 [P < .001], respectively). Positive correlations were found between frequencies of IL-13- and IL-22-producing CD4(+) and CD8(+) T cells (r = 0.5 and 0.8, respectively; P < .0001), and frequencies of IL-13-producing CLA(+) cells were also correlated with IgE levels and SCORAD scores. Patients with AD with skin infections had higher CD4(+) IL-22(+) and IL-17(+) cell frequencies, which were highly significant among CLA(-) cells (IL-22: 3.7 vs 1.7 [P < .001] and IL-17: 1.7 vs 0.6 [P < .001]), with less significant effects among CLA(+) T cells (IL-22: 11 vs 7.5, P = .04). CONCLUSIONS Severe AD is accompanied by expansion of skin-homing TH2/TC2 and TH22/TC22 subsets with lower TH1/TC1 frequencies. These data create a critical basis for studying alterations in immune activation in adults and pediatric patients with AD.

Cyclosporine in patients with atopic dermatitis modulates activated inflammatory pathways and reverses epidermal pathology.

BACKGROUND Atopic dermatitis (AD) is the most common inflammatory disease. Evolving disease models link changes in epidermal growth and differentiation to T(H)2/T(H)22 cytokine activation. However, these models have not been tested by in vivo suppression of T-cell cytokines. Cyclosporine (CsA) is an immunosuppressant that is highly effective for severe disease, but its mechanism in AD skin lesions has not been studied. OBJECTIVE We sought to establish the ability of a systemic immunosuppressant to modulate immune and epidermal alterations that form the pathogenic disease phenotype and to correlate changes with clinical improvement. METHODS CsAs effects on AD skin pathology were evaluated by using gene expression and immunohistochemistry studies in baseline, week 2, and week 12 lesional and nonlesional biopsy specimens from 19 patients treated with 5 mg/kg/d CsA for 12 weeks. RESULTS After 2 and 12 weeks of treatment, we observed significant reductions of 51% and 72%, respectively, in SCORAD scores. Clinical improvements were associated with significant gene expression changes in lesional but also nonlesional skin, particularly reductions in levels of T(H)2-, T(H)22-, and some T(H)17-related molecules (ie, IL-13, IL-22, CCL17, S100As, and elafin/peptidase inhibitor 3), and modulation of epidermal hyperplasia and differentiation measures. CONCLUSIONS This is the first study that establishes a relationship between cytokine activation and molecular epidermal alterations, as well as correlations between disease biomarkers in the skin and clinical improvement. The reversal of the molecular phenotype with CsA and the associated biomarkers can serve as a reference for the successful modulation of tissue inflammation with specific immune antagonists in future studies, contributing to the understanding of the specific cytokines involved in epidermal pathology.

IL-17 and TNF Synergistically Modulate Cytokine Expression while Suppressing Melanogenesis: Potential Relevance to Psoriasis

Inflammation-associated pigmentation changes are extremely common, but the etiology behind this clinical observation remains elusive. Particularly, it is unclear how the myriad of cytokines known to be involved in inflammatory skin processes affect epidermal melanocytes. We sought to determine how IL-17 and TNF influence normal human melanocytes, as these two cytokines have been implicated in various skin diseases. IL-17 and TNF jointly stimulated broad inductions of cytokines , including melanoma mitogens CXCL1 and IL-8. Moreover, IL-17 and TNF synergistically inhibited pigmentation-related signaling and melanin production, and induced keratinocytes production of β-defensin 3, an antagonist for melanocortin-receptor 1. When analyzing psoriasis lesions that are known to over express IL-17 and TNF, we observed an increase in melanocyte number and a simultaneous decrease in pigmentation signaling. Furthermore, therapeutic neutralization of TNF and IL-17 with mAbs results in a rapid recovery of pigment gene expression in psoriasis lesions. These results demonstrate that IL-17 and TNF can impact both the growth and pigment production of melanocytes, which may contribute to the pigmentation changes associated with psoriasis. These findings may allow the development of novel therapeutics for pigmentary disorders and bring new insights into the immune milieu surrounding melanocytes and related neoplasms.

Extracellular Tau Oligomers Produce An Immediate Impairment of LTP and Memory

Non-fibrillar soluble oligomeric forms of amyloid-β peptide (oAβ) and tau proteins are likely to play a major role in Alzheimer’s disease (AD). The prevailing hypothesis on the disease etiopathogenesis is that oAβ initiates tau pathology that slowly spreads throughout the medial temporal cortex and neocortices independently of Aβ, eventually leading to memory loss. Here we show that a brief exposure to extracellular recombinant human tau oligomers (oTau), but not monomers, produces an impairment of long-term potentiation (LTP) and memory, independent of the presence of high oAβ levels. The impairment is immediate as it raises as soon as 20 min after exposure to the oligomers. These effects are reproduced either by oTau extracted from AD human specimens, or naturally produced in mice overexpressing human tau. Finally, we found that oTau could also act in combination with oAβ to produce these effects, as sub-toxic doses of the two peptides combined lead to LTP and memory impairment. These findings provide a novel view of the effects of tau and Aβ on memory loss, offering new therapeutic opportunities in the therapy of AD and other neurodegenerative diseases associated with Aβ and tau pathology.

Increased Tc22 and Treg/CD8 Ratio Contribute to Aggressive Growth of Transplant Associated Squamous Cell Carcinoma

Immune suppressed organ transplant recipients suffer increased morbidity and mortality from primary cutaneous SCC. We studied tumor microenvironment in transplant-associated SCC (TSCC), immune-competent SCC and normal skin by IHC, IF and RT-PCR on surgical discard. We determined T cell polarization in TSCC and SCC by intracellular cytokine staining of T cell crawl outs from human skin explants. We studied the effects of IL-22, an inducer of keratinocyte proliferation, on SCC proliferation in vitro. SCC and TSCC are both associated with significantly higher numbers of CD3+ and CD8+ T cells compared to normal skin. TSCC showed a higher proportion of Foxp3+ T regs to CD8+ T cells compared to SCC and a lower percentage of IFN-γ producing CD4+ T cells. TSCC, however, had a higher percentage of IL-22 producing CD8+ T cells compared to SCC. TSCC showed more diffuse Ki67 and IL-22 receptor (IL-22R) expression by IHC. IL-22 induced SCC proliferation in vitro despite serum starvation. Diminished cytotoxic T cell function in TSCC due to decreased CD8/T-reg ratio may permit tumor progression. Increased IL-22 and IL-22R expression could accelerate tumor growth in transplant patients. IL-22 may be an attractive candidate for targeted therapy of SCC without endangering allograft survival.

Dominant Th1 and Minimal Th17 Skewing in Discoid Lupus Revealed by Transcriptomic Comparison with Psoriasis

Discoid lupus erythematosus (DLE) is the most common skin manifestation of lupus. Despite its high frequency in systemic lupus in addition to cases without extracutaneous manifestations, targeted treatments for DLE are lacking, likely due to a dearth of knowledge of the molecular landscape of DLE skin. Here, we profiled the transcriptome of DLE skin in order to identify signaling pathways and cellular signatures that may be targeted for treatment purposes. Further comparison of the DLE transcriptome to that of psoriasis, a useful reference given our extensive knowledge of molecular pathways in this disease, provided a framework to identify potential therapeutic targets. Although a growing body of data supports a role for IL-17 and Th17 cells in systemic lupus, we show a relative enrichment of IFN-γ-associated genes without that for IL-17-associated genes in DLE. Extraction of T cells from the skin of DLE patients identified a predominance of IFN-γ-producing Th1 cells and an absence of IL-17-producing Th17 cells, complementing the results from whole skin transcriptomic analyses. These data therefore support investigations into treatments for DLE that target Th1 cells or the IFN-γ signaling pathway.

Diverse activation and differentiation of multiple B-cell subsets in patients with atopic dermatitis but not in patients with psoriasis

BACKGROUND Atopic dermatitis (AD) and psoriasis pathogeneses involve skin barrier impairment and immune dysregulation; however, the contribution of B-cell imbalances to these diseases has not yet been determined. OBJECTIVE We sought to quantify B-cell populations and antibody-secreting cells in the blood of patients with AD, patients with psoriasis, and control subjects. METHODS We studied 34 adults with moderate-to-severe AD (mean SCORAD score, 65), 24 patients with psoriasis (mean Psoriasis Area and Severity Index score, 16), and 27 healthy subjects using an 11-color flow cytometric antibody panel. IgD/CD27 and CD24/CD38 core gating systems were used to determine frequencies of plasmablasts and naive, memory, transitional, and activated B cells. RESULTS We measured increased CD19(+)CD20(+) B-cell counts in the skin and blood of patients with AD (P < .01). Significantly higher frequencies of chronically activated CD27(+) memory and nonswitched memory B cells were observed in patients with AD (P < .05), with lower values of double-negative populations (4% for patients with AD vs. 7% for patients with psoriasis [P = .001] and 6% for control subjects [P = .02]). CD23 expression was highest in patients with AD and correlated with IgE levels (P < .01) and disease severity (r = 0.6, P = .0002). Plasmablast frequencies and IgE expression were highest in all memory subsets of patients with AD (P < .01). Finally, CD19(+)CD24(++)CD38(++) transitional and CD19(+)CD24(-)CD38(-) new memory B-cell counts were higher in patients with AD versus those in patients with psoriasis (2.8% vs. 1.4% [P = .001] and 9.2% vs. 5.7% [P = .02], respectively). CONCLUSIONS AD is accompanied by systemic expansion of transitional and chronically activated CD27(+) memory, plasmablast, and IgE-expressing memory subsets. These data create a critical basis for the future understanding of this debilitating skin disease.