The Oxidative Stress-Induced miR-200c Is Upregulated in Psoriasis and Correlates with Disease Severity and Determinants of Cardiovascular Risk

Psoriasis is a chronic inflammatory skin disease associated with reactive oxygen species (ROS) increase and a higher risk of cardiovascular (CV) events. We previously showed that the miR-200 family (miR-200s) is induced by ROS, miR-200c being the most upregulated member responsible for apoptosis, senescence, ROS increase, and nitric oxide decrease, finally causing endothelial dysfunction. Moreover, circulating miR-200c increases in familial hypercholesterolemic children and in plaques and plasma of atherosclerotic patients, two pathologies associated with increased ROS. Given miR-200s' role in endothelial dysfunction, ROS, and inflammation, we hypothesized that miR-200s were modulated in lesional skin (LS) and plasma of psoriatic patients (Pso) and that their levels correlated with some CV risk determinants at a subclinical level. All Pso had severe psoriasis, i.e., Psoriasis Area and Severity Index (PASI) > 10, and one of the following: at least two systemic psoriasis treatments, age at onset < 40 years, and disease duration > 10 years. RNA was extracted from plasma (Pso, N = 29; Ctrl, N = 29) and from nonlesional skin (NLS) and LS of 6 Pso and 6 healthy subject skin (HS) biopsies. miR-200 levels were assayed by quantitative RT-PCR. We found that all miR-200s were increased in LS vs. NLS and miR-200c was the most expressed and upregulated in LS vs. HS. In addition, circulating miR-200c and miR-200a were upregulated in Pso vs. Ctrl. Further, miR-200c positively correlated with PASI, disease duration, left ventricular (LV) mass, LV relative wall thickness (RWT), and E/e', a marker of diastolic dysfunction. Multiple regression analysis indicates a direct association between miR-200c and both RWT and LV mass. Circulating miR-200a correlated positively only with LV mass and arterial pressure augmentation index, a measure of stiffness, although the correlations were nearly significant (P = 0.06). In conclusion, miR-200c is upregulated in LS and plasma of Pso, suggesting its role in ROS increase and inflammation associated with CV risk in psoriasis.

P4442miR-200c is up-regulated in lesional skin and plasma of patients affected by psoriasis and correlates with disease severity and cardiovascular risk

Background

Psoriasis is a common, chronic inflammatory disease involving skin. Psoriatic patients mostly show the plaque-type clinical form and several comorbidities, including cardiovascular (CV) diseases. We previously showed that miR-200 family members (miR-200s) is induced by reactive oxygen species (ROS). miR-200c is the most up-regulated member and is responsible for apoptosis, senescence, endothelial dysfunction, ROS increase and nitric oxide decrease. Circulating miR-200c is upregulated in Familial Hypercholesterolemia in children, a pathology associated with ROS increase and atherosclerosis. miR-200c increases also in carotid plaques and plasma of atherosclerotic pts vs healthy subjects and positively correlates with plaque instability biomarkers.

Purpose

Given the role of miR-200s in ROS modulation, endothelial dysfunction, cardiac remodelling and inflammation, all features associated with psoriasis, we wondered whether miR-200s were modulated in lesional skin (LS) and plasma of psoriatic patients (Pso) and whether miR-200 levels correlated with CV risk.

Methods

29 Pso were compared to 29 control subjects (Ctrl) age- and sex-matched. All Pso had a severe psoriasis, defined as Psoriasis Area and Severity Index (PASI) >10 and one of the following: at least two systemic psoriasis treatments, psoriasis onset <40 years of age, disease duration >10 years. Exclusion criteria were: diabetes, cerebrovascular events, myocardial infarction, and/or myocardial revascularization, psoriatic arthritis. Total RNA was extracted from plasma and miR-200 levels assayed by quantitative real-time PCR. The clinical parameters were similar between the two groups except for Total Cholesterol (mg/dl) (Ctrl 193.3±6.2; Pso 213.2±6.9; P<0.05). Blood pressure measurement, wave reflection analysis and pulse wave velocity (PWV) were similar between groups, echocardiographic parameters were different for left ventricular (LV) mass index (g/m2) (Ctrl 84.2±5.2; Pso 102.5±4.7; P<0.05) and relative wall thickness (RWT) (Ctrl 0.4±0.0; Pso 0.48±0.0; P<0.01). Total RNA was extracted from biopsies of nonlesional (NLS) and LS of 6 Pso and 6 healthy subject skin (HS).

Results

miR-200s were increased in LS vs NLS samples. miR-200c was the most expressed and was upregulated also in LS vs HS (2.0+0.2 fold-increase; P<0.01). Circulating miR-200c (2.5+0.5 fold-increase; P<0.05) and miR-200a (4.8+0.7 fold; P<0.0001) were up-regulated in Pso vs Ctr. Circulating miR-200c positively correlated with LV mass (Rs=0.32; P<0.05), RWT (Rs=0.32; P<0.05) and diastolic dysfunction assessed with E/e' parameters (Rs=0.34; P<0.05). Circulating miR-200a correlated only with LV mass, although not significantly (Rs=0.30; P=0.06). miR-200c exhibited a significant positive correlation with PASI (Rs=0.43; P<0.05) and with disease duration of (Rs=0.40; P<0.05). Conclusion miR-200c is upregulated in skin plaques and plasma of Pso, and might be involved in inflammatory and CV risk increase in these patients.

Acknowledgement/Funding

Ministero della Salute RF-2016-02362708 to AM and MCC

Luteolin-7-glucoside inhibits IL-22/STAT3 pathway, reducing proliferation, acanthosis, and inflammation in keratinocytes and in mouse psoriatic model

The epidermis is a dynamic tissue in which keratinocytes proliferate in the basal layer and undergo a tightly controlled differentiation while moving into the suprabasal layers. The balance between keratinocyte proliferation, differentiation, and death is essential, and its perturbation can result in pathological changes. Some common skin diseases, such as psoriasis, are characterized by hyperproliferation accompanied by inflammatory reactions, suggesting that molecules with topical anti-inflammatory and ROS scavenging abilities may be useful for their treatment. Here we investigate the potential of the flavone Luteolin-7-glucoside (LUT-7G) as a treatment for psoriasis. We show that LUT-7G leads to a modification of the cell cycle and the induction of keratinocyte differentiation, with modification of energy, fatty acid, and redox metabolism. LUT-7G treatment also neutralizes the proliferative stimulus induced by the proinflammatory cytokines IL-22 and IL-6 in HEKn. Moreover, in the Imiquimod (IMQ) mouse model of psoriasis, topical administration of LUT-7G leads to a marked reduction of acanthosis and re-expression of epidermal differentiation markers. Dissection of the IL-22 signalling pathway, activated by IMQ treatment, demonstrates that LUT-7G impairs the nuclear translocation of phosphorylated (activated) STAT3, blocking the IL-22 signalling cascade. Thus LUT-7G appears to be a promising compound for the treatment of hyperproliferative and inflammatory skin diseases, such as psoriasis.

Pathobiology of chronic inflammatory skin diseases: interplay between keratinocytes and immune cells as a target for anti-inflammatory drugs

Inflammatory dermatoses encompass an enormous area of dermatopathology. These diseases are triggered and maintained by aberrant responses of the cells of the skin immune system. In the last decade it has become clear that epidermal keratinocytes are highly active immunological cells, with a major control over the acute and the chronic phase of skin inflammation by means of cytokine/chemokine production and surface molecule expression. In their turn, these rather disease-specific events driven by keratinocytes lead to a rich inflammatory infiltrate in the whole skin including the upper layers of the epidermis, and eventually in the aggravation and/or perpetuation of the skin disorder. Recently introduced single molecule-targeted biological drugs are offering the best demonstration that a fine definition of the molecular pathways underlying skin disorders is now necessary to identify the relevant therapeutic targets and finally obtain successful treatment of these diseases. In this review, we will summarize recent progress in our understanding of the immunologic basis of psoriasis, allergic contact dermatitis and atopic dermatitis, with special emphasis on potentially effective targets for novel anti-inflammatory drugs.

T-cell subpopulations in the development of atopic and contact allergy

Remarkable progress has been made in our understanding of the pathogenesis of skin diseases mediated by T cells. T-cell subsets responsible for the expression and regulation of allergic contact dermatitis to small chemicals or 'haptens' have been defined further, and the dynamics of T cells involved in the pathogenesis of atopic dermatitis have been clarified. In addition, studies are beginning to reveal the important contribution of skin resident cells to atopic dermatitis and the underlying molecular mechanisms.

A cytokine-to-chemokine axis between T lymphocytes and keratinocytes can favor Th1 cell accumulation in chronic inflammatory skin diseases

The recruitment of T cells into the skin is regulated by chemokines released by resident cells. In this study, we found that normal human keratinocytes activated with Th1-derived supernatant (sup) expressed early (6-12 h) IP-10/CXCL10, MCP-1/CCL2, IL-8/CXCL8, and I-309/CCL1 mRNAs and with slower kinetics (24-96 h), RANTES/CCL5 and MDC/CCL22 mRNAs. Upon stimulation with the Th1 sup, keratinocytes secreted high levels of RANTES, IP-10, MCP-1, and IL-8 and moderate levels of I-309 and MDC. Although much less efficiently, Th2 sup could also induce keratinocyte expression of IL-8, IP-10, RANTES, and MCP-1 but not of I-309 and MDC. TARC/CCL17 was not significantly induced by any stimuli. Sup from keratinocytes activated with Th1-derived cytokines elicited a strong migratory response of Th1 cells and a limited migration of Th2 cells, whereas sup from Th2-activated keratinocytes promoted a moderate migration of Th1 and Th2 lymphocytes. Thus, keratinocytes appear considerably more sensitive to Th1- than to Th2-derived lymphokines in terms of chemokine release and can support the preferential accumulation of Th1 lymphocytes in the skin.

Fractalkine (CX3CL1) as an amplification circuit of polarized Th1 responses

Fractalkine (FKN, CX3CL1) is a membrane-bound CX3C chemokine induced by primary proinflammatory signals in vascular endothelial cells (ECs). Here we examined the role of FKN in polarized Th1 or Th2 responses. Proinflammatory signals, including LPS, IL-1, TNF, and CD40 ligand, induced FKN, as did IFN-gamma, which had synergistic activity with TNF. IL-4 and IL-13 did not stimulate the expression of FKN and markedly reduced induction by TNF and IFN-gamma. TNF alone or combined with IFN-gamma also induced release of soluble FKN, which was inhibited by IL-4 and IL-13. In light of this differential regulation of FKN by the master cytokines that control polarized responses, we analyzed the interaction of FKN with natural killer (NK) cells and polarized T-cell populations. NK cells expressed high levels of the FKN receptor CX3CR1 and responded to FKN. CX3CR1 was preferentially expressed in Th1 compared with Th2 cells. Th1 but not Th2 cells responded to FKN. By immunohistochemistry, FKN was expressed on ECs in psoriasis, a Th1-dominated skin disorder, but not in Th2-driven atopic dermatitis. Similarly, ECs in Mycobacterium tuberculosis granulomatous lymphadenitis, but not those in reactive lymph node hyperplasia or in Castelman's disease, showed immunoreactive FKN. These results indicate that regulated expression of FKN in ECs participates in an amplification circuit of polarized type I responses.

Regulatory activity of autocrine IL-10 on dendritic cell functions

IL-10 is a critical cytokine that blocks the maturation of dendritic cells (DCs), but the relevance of autocrine IL-10 on DC functions has not been investigated. In this study, we found that immature monocyte-derived DCs released low but sizeable amounts of IL-10. After stimulation with bacteria, LPS, lipoteichoic acid, or soluble CD40 ligand, DCs secreted high levels of IL-10. Addition of an anti-IL-10-neutralizing Ab to immature DCs as well as to soluble CD40 ligand- or LPS-maturing DCs led to enhanced expression of surface CD83, CD80, CD86, and MHC molecules and markedly augmented release of TNF-alpha and IL-12, but diminished IL-10 mRNA expression. Moreover, DCs treated with anti-IL-10 Ab showed an increased capacity to activate allogeneic T cells and primed naive T cells to a more prominent Th1 polarization. DC maturation and IL-10 neutralization were associated with enhanced accumulation of the IL-10 receptor binding chain (IL-10R1) mRNA and intracellular IL-10R1 protein. In contrast, surface IL-10R1 and IL-10 binding activity diminished in mature DCs. These results indicate that autocrine IL-10 prevents spontaneous maturation of DCs in vitro, limits LPS- and CD40-mediated maturation, and increases IL-10 production by DCs. Moreover, IL-10R expression appears to be regulated by both transcriptional and posttranscriptional mechanisms. Endogenous IL-10 and IL-10R can be relevant targets for the manipulation of DC functions.

Effector and regulatory T cells in allergic contact dermatitis

Allergic contact dermatitis is a prototypic T-cell-mediated disease that has a socio-economic impact in industrialized countries. Here, Andrea Cavani and colleagues highlight recent developments in the T-cell-based effector and regulatory mechanisms of this common skin disorder.

Dendritic cells as a major source of macrophage-derived chemokine/CCL22 in vitro and in vivo

Macrophage-derived chemokine (MDC)/CCL22 is a CC chemokine active on dendritic cells (DC), NK cells and Th2 lymphocytes. The present study was aimed at comprehensively investigating MDC production in vitro and in vivo. DC were the most potent producers of MDC among leukocytes tested. Endothelial cells did not produce MDC under a variety of conditions. Signals that induce maturation (lipopolysaccharide, IL-1, TNF, CD40 ligand, recognition of bacteria and yeast) dramatically augmented MDC production, and dexamethasone and vitamin D3 blocked it. Prostaglandin E(2), which blocked the acquisition of IL-12 production and the capacity to promote Th1 generation, did not affect MDC production. Using mass spectrometry-based techniques, DC supernatants were found to contain N-terminally truncated forms of MDC [MDC(3-69), MDC(5-69) and MD(C7-69)] as well as the full-length molecule. In vivo, CD1a(+), CD83(+), MDC(+) DC were found in reactive lymph nodes, and in Langerhans' cell histiocytosis. Skin lesions of atopic dermatitis patients showed that CD1a(+) or CD1b(+) DC, and DC with a CD83(+) phenotype were responsible for MDC production in this Th2-oriented disorder. Thus, DC are the predominant source of MDC in vitro and in vivo under a variety of experimental and clinical conditions. Processing of MDC to MDC(3-69) and shorter forms which do not recognize CCR4 is likely to represent a feedback mechanism of negative regulation.

Chemokine receptor expression and function in CD4+ T lymphocytes with regulatory activity

We have investigated the chemokine receptor expression and migratory behavior of a new subset of nickel-specific skin-homing regulatory CD4(+) T cells (Th(IL-10)) releasing high levels of IL-10, low IFN-gamma, and undetectable IL-4. These cells inhibit in a IL-10-dependent manner the capacity of dendritic cells to activate nickel-specific Tc1 and Th1 lymphocytes. RNase protection assay and FACS analysis revealed the expression of a vast repertoire of chemokine receptors on resting Th(IL-10), including the Th1-associated CXCR3 and CCR5, and the Th2-associated CCR3, CCR4, and CCR8, the latter at higher levels compared with Th2 cells. The most active chemokines for resting Th(IL-10), in terms of calcium mobilization and in vitro migration, were in order of potency: CCL2 (monocyte chemoattractant protein-1, CCR2 ligand), CCL4 (macrophage-inflammatory protein-1beta, CCR5 ligand), CCL3 (macrophage-inflammatory protein-1alpha, CCR1/5 ligand), CCL17 (thymus and activation-regulated chemokine, CCR4 ligand), CCL1 (I-309, CCR8 ligand), CXCL12 (stromal-derived factor-1, CXCR4), and CCL11 (eotaxin, CCR3 ligand). Consistent with receptor expression down-regulation, activated Th(IL-10) exhibited a reduced or absent response to most chemokines, but retained a significant migratory capacity to I-309, monocyte chemoattractant protein-1, and thymus and activation-regulated chemokine. I-309, which was ineffective on Th1 lymphocytes, attracted more efficiently Th(IL-10) than Th2 cells. I-309 and CCR8 mRNAs were not detected in unaffected skin and were up-regulated at the skin site of nickel-allergic reaction, with an earlier expression kinetics compared with IL-10 and IL-4. Results indicate that skin-homing regulatory Th(IL-10) lymphocytes coexpress functional Th1- and Th2-associated chemokine receptors, and that CCR8/I-309-driven recruitment of both resting and activated Th(IL-10) cells may be critically involved in the regulation of Th1-mediated skin allergic disorders.

Huriez syndrome: case report with a detailed analysis of skin dendritic cells

We report a 60-year-old man with familial scleroatrophic syndrome of Huriez who developed squamous cell carcinomas on the affected skin of the right palm. Immunohistochemical analysis showed a marked reduction in the number of CD1a+, Lag+ and S100+ epidermal Langerhans cells, but not of CD1b+ and factor XIIIa+ dermal dendritic cells, limited to palmoplantar skin. The Langerhans cell depletion was not associated with an abnormal skin content of mRNA for factors involved in Langerhans cell development or recruitment in the epidermis, including granulocyte/macrophage colony-stimulating factor, transforming growth factor-beta1 and macrophage inflammatory protein-3alpha. The results indicate that other as yet unknown mechanisms may account for the reduced number of Langerhans cells in the affected skin of such patients.

Disparate cytotoxic activity of nickel-specific CD8+ and CD4+ T cell subsets against keratinocytes

Allergic contact dermatitis (ACD) is the result of an exaggerated immune reaction to haptens mediated by skin-homing T cells, but the effector mechanisms responsible for the tissue damage are poorly understood. Here we studied the capacity of distinct subsets of hapten-specific T cells to induce apoptosis in autologous keratinocytes. Skin- and blood-derived nickel-specific CD8+ T cytotoxic 1 (Tc1) and Tc2 clones as well as CD4+ Th1 and Th2 expressed the cutaneous lymphocyte-associated Ag and exhibited strong MHC-restricted cytotoxicity against nickel-coupled B lymphoblasts, as detected by the [3H]TdR release assay. Both Tc1 and Tc2 clones, but not CD4+ T cells, displayed a significant cytotoxic activity against resting nickel-modified keratinocytes. Following IFN-gamma treatment, keratinocytes expressed MHC class II and ICAM-1 and became susceptible to Th1-mediated, but not Th2-mediated, cytotoxicity. The molecules of the two major cytotoxic pathways, Fas ligand (FasL) and perforin, were expressed by Tc1, Tc2, and Th1 cells, whereas Th2 cells expressed only FasL. Experiments performed in the presence of specific inhibitors of the perforin (concanamycin A) and FasL (brefeldin A) pathway indicated that perforin-mediated killing dominated in Tc1 and Tc2, and FasL-mediated cytotoxicity prevailed in Th2 clones, with a more heterogeneous behavior in the case of Th1 cells. Finally, perforin mRNA was expressed in ACD lesional skin, as assessed by RT-PCR analysis. In aggregate, our results indicate that keratinocytes can be target of multiple hapten-specific CTL responses, that may have distinct roles in the epidermal injury during ACD.

IL-4 enhances keratinocyte expression of CXCR3 agonistic chemokines

IFN-induced protein of 10 kDa (IP-10), monokine induced by IFN-gamma (Mig), and IFN-inducible T-cell alpha-chemoattractant (I-TAC) belong to the non-glutamate-leucine-arginine motif CXC chemokine family and act solely through the CXCR3 receptor for potent attraction of T lymphocytes. In this study, we evaluated the capacity of the T cell-derived cytokines IL-4, IL-10, and IL-17 to modulate IP-10, Mig, and I-TAC in cultured human keratinocytes and CXCR3 expression in T cells from allergic contact dermatitis (ACD). IL-4, but not IL-10 or IL-17, significantly up-regulated IFN-gamma- or TNF-alpha-induced IP-10, Mig, and I-TAC mRNA accumulation in keratinocytes and increased the levels of IP-10 and Mig in keratinocyte supernatants. Immunohistochemistry of skin affected by ACD revealed that >70% of infiltrating cells were reactive for CXCR3 and that CXCR3 staining colocalized in CD4+ and CD8+ T cells. Nickel-specific CD4+ and CD8+ T cell lines established from ACD skin produced IFN-gamma and IL-4 and expressed moderate to high levels of CXCR3. Finally, CXCR3 agonistic chemokines released by stimulated keratinocytes triggered calcium mobilization in skin-derived nickel-specific CD4+ T cells and promoted their migration, with supernatant from keratinocyte cultures stimulated with IFN-gamma and IL-4 attracting more efficaciously than supernatant from keratinocytes activated with IFN-gamma alone. In conclusion, IL-4 exerts a proinflammatory function on keratinocytes by potentiating IFN-gamma and TNF-alpha induction of IP-10, Mig, and I-TAC, which in turn may determine a prominent recruitment of CXCR3+ T lymphocytes at inflammatory reaction sites.

Interleukin-17 is produced by both Th1 and Th2 lymphocytes, and modulates interferon-gamma- and interleukin-4-induced activation of human keratinocytes

Interleukin-17 is a T-cell-derived cytokine, detected in skin affected by allergic contact dermatitis and psoriasis, which regulates keratinocyte expression of adhesion molecules and chemokines. In this study, we have analyzed whether interleukin-17 production segregates with a particular T helper (Th) cell subset, and have examined the capacity of interleukin-17 to modulate the activation of keratinocytes induced by Th1 and Th2 cytokines. A panel of 80 nickel-specific CD4+ T cell clones (36 Th0, 30 Th1, and 14 Th2) was isolated from peripheral blood or lesional skin of allergic contact dermatitis patients. Significant amounts (> 50 pg per ml) of interleukin-17 were released by about 50% of activated Th0, Th1, and Th2 cells. Interleukin-17 alone and in cooperation with interleukin-4, or to a lesser extent with interferon-gamma, decreased the interleukin-1 receptor antagonist to interleukin-1alpha ratio in the supernatants as well as in cell lysates from keratinocytes. In addition, interleukin-17 stimulated the release of growth-regulated oncogene-alpha, granulocyte-macrophage colony stimulating factor, and interleukin-6, with synergistic or additive effects when used together with interferon-gamma or interleukin-4. Interleukin-17 and interleukin-4 also increased stem cell factor release, a function that was inhibited by interferon-gamma. Moreover, interleukin-17 and interleukin-4 enhanced interferon-gamma-induced expression of intercellular adhesion molecule 1, but not CD40, on keratinocytes. The constitutive expression of interleukin-17 and interferon-gamma receptors on keratinocytes was not modulated by interleukin-17, interferon-gamma, or interleukin-4, whereas the interleukin-4 receptor was significantly downregulated by interferon-gamma. As a whole, the results indicate that interleukin-17 can participate relevantly in T-cell-mediated skin immune responses by amplifying both interferon-gamma- and interleukin-4-induced activation of keratinocytes.

Human CD4+ T lymphocytes with remarkable regulatory functions on dendritic cells and nickel-specific Th1 immune responses

The contribution of T helper (Th) and T cytotoxic (Tc) type 1 lymphocytes in the expression of allergic contact dermatitis to haptens has been amply documented. Conversely, the existence of T cell-based regulatory mechanisms has been poorly investigated. Here, we examined the properties of a subset of nickel-specific CD4+ T cells displaying the cytokine profile (IL-10 , IL-5 , IFN-gamma+/-, IL-4+/-) of T regulatory cells 1 (Tr1) and with the potential to down-modulate immune responses to nickel. Tr1 clones were isolated from skin challenged with NiSO4 and peripheral blood of nickel-allergic patients, and from the blood of healthy individuals. Tr1 clones expressed CD25, CD28, CD30, CD26, and the IL-12 receptor beta2 chain upon activation, whereas the lymphocyte activation antigen-3 was present on 50% of the clones. Monocytes precultured with Tr1 cells in the presence of nickel, or treated with Tr1-derived supernatant, exhibited a markedly diminished capacity to stimulate nickel-specific Th1 responses. Tr1 supernatants also blocked the differentiation of dendritic cells (DC) from monocytes, as well as DC maturation and IL-12 production induced by lipopolysaccharide. As a consequence, the ability of DC to stimulate nickel-specific Th1 and Tc1 responses was greatly impaired. These inhibitory effects were completely prevented by IL-10, but not IL-5, neutralization. In aggregate, the results indicate that Tr1 cells can potently regulate the expression of Th1-mediated allergic diseases via release of IL-10.

Cross-linking of membrane CD43 mediates dendritic cell maturation

CD43/leukosialin is a major sialoglycoprotein of the dendritic cell (DC) surface, which can regulate cell adhesion and has the potential to mediate cell activation signals. Monocyte-derived DC transiently incubated with the anti-CD43 mAb, MEM-59, or with F(ab')2 fragments, but not with monovalent Fab fragments or control IgG, 24 h later showed increased levels of membrane HLA-DR, CD54, CD40, CD80, CD86, and CD83. In parallel, CD43 cross-linking induced synthesis and release of IL-1beta, IL-6, TNF-alpha, IL-12, and IL-10. CD43 ligation inhibited the endocytic activity of DC, and enhanced the capacity of DC to stimulate T cell proliferation in the primary allogeneic and autologous MLR assay. In addition, anti-CD43-treated DC were less efficient at presenting native HIV-1 reverse transcriptase to a specific CD4+ T cell clone, whereas presentation of the reverse transcriptase 55-72 peptide to the same clone was increased. Finally, MEM-59 or its F(ab')2 fragments elicited a rise in intracellular free calcium and tyrosine phosphorylation of a 25-kDa protein in DC. The results thus indicate that CD43 cross-linking with specific ligands induces activation and functional maturation of DC.

IL-17 is produced by nickel-specific T lymphocytes and regulates ICAM-1 expression and chemokine production in human keratinocytes: synergistic or antagonist effects with IFN-gamma and TNF-alpha

IL-17 is a novel T cell-derived cytokine that can regulate the functions of a variety of cell types. In this study, we investigated whether hapten-specific T cells isolated from patients with allergic contact dermatitis (ACD) to nickel produce IL-17 and the effects of IL-17 alone or in combination with IFN-gamma or TNF-alpha on the immune activation of keratinocytes. Skin affected with ACD to nickel and skin-derived, nickel-specific CD4+ T cell lines expressed IFN-gamma, TNF-alpha, and IL-17 mRNAs. Four of seven nickel-specific CD4+ T cell clones positive for the skin-homing receptor, cutaneous lymphocyte-associated Ag, were shown to corelease IL-17, IFN-gamma, and TNF-alpha. In contrast, two nickel-specific CD8+ T cell clones failed to synthesize IL-17. Normal human keratinocytes were found to express constitutively the IL-17 receptor gene. IL-17 specifically and dose-dependently augmented IFN-gamma-induced ICAM-1 expression on keratinocytes at both the mRNA and the protein level, whereas HLA-DR, MHC class I, and CD40 levels were not modulated by IL-17. On the other hand, IL-17 alone did not affect ICAM-1 or enhance TNF-alpha-induced ICAM-1. In addition, IL-17, both directly and in synergism with IFN-gamma and/or TNF-alpha, stimulated synthesis and release of IL-8 by keratinocytes. In contrast, IFN-gamma- and TNF-alpha-induced production of RANTES was markedly inhibited by IL-17, and the synthesis of macrophage chemotactic protein 1 was not changed. Taken together, the results suggest that IL-17 is an important player of T cell-mediated skin immune responses, with synergistic or antagonist effects on IFN-gamma- and TNF-alpha-stimulated keratinocyte activation.

Interferon-gamma-stimulated human keratinocytes express the genes necessary for the production of peptide-loaded MHC class II molecules

Keratinocytes exposed to interferon (IFN)-gamma synthesize major histocompatibility complex class II antigens both in vivo and in vitro; however, the expression of class II accessory genes has not yet been investigated. In this study, we examined the capacity of normal human keratinocytes activated with IFN-gamma to express HLA-DR, HLA-DM, and invariant chain genes as well as two major transcription regulatory genes, class II transactivator and RFX5. Cultured keratinocytes were shown to synthesize low levels of DM alpha, invariant chain p33, and RFX5 transcription factor. Upon treatment with IFN-gamma, expression of RFX5, DM alpha, and invariant chain p33 mRNA increased, whereas class II transactivator mRNA appeared de novo, followed by the expression of DR alpha, DMbeta, and invariant chain p41 genes. Western blot analysis showed that both p33 and p41 invariant chain forms and DM became detectable in keratinocytes after stimulation with IFN-gamma, with a higher p41/p33 ratio compared with Raji B cells. Finally, HLA-DR molecules present on IFN-alpha-treated keratinocytes were shown to be remarkably resistant to sodium dodecyl sulfate denaturation at room temperature, a feature that class II molecules acquire when their groove is properly loaded with peptide. These results suggest that human keratinocytes activated with IFN-gamma possess the biochemical requirements for the generation of functional class II peptide complexes.

Cetirizine and hydrocortisone differentially regulate ICAM-1 expression and chemokine release in cultured human keratinocytes

BACKGROUND

Cetirizine is a H1 histamine antagonist which possesses anti-inflammatory properties through inhibition of leucocyte recruitment and activation, and reduction of ICAM-1 expression on mucosal epithelial cells. No studies have addressed the potential anti-inflammatory activities of cetirizine on skin keratinocytes.

OBJECTIVES

Cetirizine and hydrocortisone were compared in their capacity to counteract human keratinocytes activation by IFNgamma. In particular, expression of immuno-modulatory membrane molecules and chemokine release have been examined.

METHODS

Keratinocyte cultures established from normal skin of healthy donors were activated by IFNgamma (100-500 U/mL) in the absence or presence of cetirizine (10(-3)-10(3) microM) or hydrocortisone (10(-3)-10(2) microM), and tested for expression of ICAM-1, HLA-DR, MHC class I and CD40 as well as for release of RANTES, IL-8, macrophage chemotactic protein-1 (MCP-1) and granulocyte macrophage-colony stimulating factor (GM-CSF).

RESULTS

Cetirizine at high concentrations (10(2)-10(3) microM) markedly inhibited IFNgamma-induced expression of membrane ICAM-1, HLA-DR and up-regulation of MHC class I, but had no effect on CD40 expression. In contrast, hydrocortisone (10(2) microM) enhanced IFNgamma-induced membrane ICAM-1, reduced expression of HLA-DR and did not alter expression of MHC class I and CD40. Consistently, high doses of cetirizine decreased, whereas hydrocortisone increased, soluble ICAM-1 levels in the supernatants of IFNgamma-treated keratinocytes. The inhibiting and stimulating effects of cetirizine and hydrocortisone, respectively, on ICAM-1 expression were confirmed at the mRNA level by Northern blot analysis. Finally, cetirizine, but not hydrocortisone, inhibited the release of MCP-1 and RANTES from IFNgamma-stimulated keratinocytes. In contrast, hydrocortisone, but not cetirizine, reduced GM-CSF and IL-8 release.

CONCLUSIONS

The results indicate that cetirizine has the capacity to block the IFNgamma-induced activation of keratinocytes, and thus can exert important regulatory effects on TH1 cell-mediated immune responses in the skin. The high doses required for evidencing these activities suggest the potential benefits of a topical use of cetirizine.

Granulocyte macrophage colony-stimulating factor is overproduced by keratinocytes in atopic dermatitis. Implications for sustained dendritic cell activation in the skin

Lesional skin of atopic dermatitis (AD) harbors high numbers of dendritic cells with enhanced stimulatory capacity for T lymphocytes. In this study, lesional AD skin was shown to stain heavily in both epidermal and dermal compartments for GM-CSF, a cytokine crucial to dendritic cell functions. Keratinocyte cultures established from uninvolved skin of AD patients exhibited markedly increased spontaneous and PMA-stimulated release of GM-CSF compared with keratinocytes from nonatopic controls. Correspondingly, keratinocytes from AD patients showed higher constitutive as well as PMA-induced GM-CSF gene expression. Larger amounts of GM-CSF were produced by AD keratinocytes, also in response to IL-1alpha, but not after stimulation with LPS, lipoteichoic acid, or staphylococcal enterotoxin B. Hydrocortisone reduced GM-CSF gene expression and protein release in both atopic and control keratinocytes. Supernatants from atopic keratinocytes were able to strongly stimulate PBMC proliferation in a GM-CSF-dependent manner. Moreover, conditioned medium from PMA-treated AD keratinocytes, together with exogenous IL-4, could support phenotypical and functional maturation of peripheral blood precursors into dendritic cells. Enhanced production of GM-CSF by keratinocytes may contribute relevantly to the establishment and chronicity of AD lesions, in particular to the increased number, sustained activation, and enhanced antigen-presenting functions of dendritic cells.

Determination of the enantiomeric purity of N-propionyl-6,7-dimethoxy-2-aminotetralin by cyclodextrin-modified micellar electrokinetic chromatography

N-Propionyl-6,7-dimethoxy-2-aminotetralin (Z12231A), a useful intermediate in the synthesis of dopaminergic agonists, was resolved into its enantiomers by high-performance capillary electrophoresis. Cyclodextrin-modified micellar electrokinetic chromatography was employed with a combination of chiral selectors both in the aqueous phase (a hydroxyalkyl-beta-cyclodextrin) and in the micellar phase (sodium taurodeoxycholate). The absolute amount of the two chiral selectors as well as their ratio were found to be the most critical parameters in order to optimize separation. A resolution factor >3.5 was obtained, allowing a high amount of solute to be loaded in order to improve the detection limit. The reproducibility of the assay was also evaluated.

A cell- and developmental stage-specific promoter drives the expression of a truncated c-kit protein during mouse spermatid elongation

In the postnatal testis, the c-kit transmembrane tyrosine-kinase receptor is expressed in type A spermatogonia, and its transcription ceases at the meiotic phase of spermatogenesis. Alternative, shorter c-kit transcripts are expressed in post-meiotic germ cells. These transcripts should encode a truncated version of the c-kit protein, lacking the extracellular, the transmembrane and part of the intracellular tyrosine-kinase domains. The 5′ end of the alternative c-kit transcripts maps within an intron of the mouse c-kit gene. We now show that this intron contains a promoter active in nuclear extracts of round spermatids, and that two discrete sequences upstream of the transcriptional start site bind spermatid-specific nuclear factors. Deletion of both these sequences abolishes activity of the promoter in vitro. We have also established that this promoter is functional in vivo, in a tissue-and cell-specific fashion, since intronic sequences drive the expression of the E. coli lacZ reporter gene in transgenic mice specifically in the testis. Transgene expression is confined to haploid germ cells of seminiferous tubules, starting from spermatids at step 9, and disappearing at step 13, indicating that cryptic promoter within the 16th intron of the mouse c-kit gene is active in a short temporal window at the end of the transcriptional phase of spermiogenesis. In agreement with these data, western blot experiments using an antibody directed against the carboxy-terminal portion of the mouse c-kit protein showed that a polypeptide, of the size predicted by the open reading frame of the spermatid-specific c-kit cDNA, accumulates in the latest stages of spermatogenesis and in epididymal spermatozoa. An immunoreactive protein of the same size can be produced in both eukaryotic and prokaryotic artificial expression systems.

The same sequence mediates activation of the human urokinase promoter by cAMP in mouse Sertoli cells and by SV40 large T antigen in COS cells

Cell-specific activation by follicle-stimulating hormone and its intracellular mediator, cAMP, of the human urokinase promoter in mouse Sertoli cells requires overlapping purine-rich and GC-rich sequences between -54 and -42 from the transcriptional start site. We have previously shown that binding of unidentified nuclear factors to these sequences is induced by cAMP stimulation, and that sequences from the enhancerless SV40 replication origin can interfere with the binding, whereas consensus Sp1 binding sites are ineffective. We now show that sequences within the SV40 origin able to compete for the formation of cAMP-induced DNA-protein complexes in Sertoli cell nuclear extracts are binding sites for the SV40 large T antigen. Large T antigen expressed in COS cells binds the cAMP-responsive sequences of the human urokinase gene and transactivates the proximal promoter, thus mimicking the effect of nuclear factors induced by cAMP in Sertoli cells. We show that Egr-1 is one of the factors present in cAMP-induced DNA-protein complexes formed between the human urokinase promoter and Sertoli cell nuclear extracts. However, Egr-1 levels are similar in unstimulated and cAMP-treated Sertoli cells, suggesting that this factor interacts with a different GC-box binding factor, that we have previously shown to be strongly induced by cAMP treatment of Sertoli cells. We propose that SV40 large T antigen in COS cells can mimick the action of heterodimers formed in cAMP stimulated Sertoli cells between Egr-1 and a cell specific cAMP-induced GC-box binding factor.

Expression of the Xist gene in urogenital ridges of midgestation male embryos

We show by RT-PCR analysis that transcripts from the Xist gene, which is normally expressed from the inactive X chromosome of female somatic cells and postnatal male germ cells, are transiently expressed also in male embryos around the time of testis differentiation, mainly in somatic cells of urogenital ridges. In the postnatal testis, we find that Xist transcripts are mainly localized within the nucleus of haploid spermatids. These findings suggest that inactivation of the X-chromosome might occur not only in adult male germ cells, but also, transiently, in somatic cells of the male urogenital ridge. Both in the embryonal gonad and in differentiating germ cells Xist expression in males overlaps the pattern of expression of the testis determining gene Sry.

Identification of 3',5'-cyclic adenosine monophosphate-inducible nuclear factors binding to the human urokinase promoter in mouse Sertoli cells

Transcription factors which recognize both the SV40 promoter and the proximal promoter region of the human urokinase-type plasminogen activator (h-uPA) gene are present in nuclear extracts from primary cultures of mouse Sertoli cells; prolonged (more than 12 h) (Bu)2cAMP stimulation of Sertoli cells induces the formation of different specific DNA-protein complexes. A discrete region in the h-uPA promoter, between -54 and -42, is essential for the formation of the cAMP-induced DNA-protein complexes. Mutation of the sequence between -54 and -42 abolishes the response to cAMP of the proximal h-uPA promoter in Sertoli cells. A protein, recognizing a sequence centered around the GC-box present between -48 and -43, is detected by Southwestern analysis, and it is clearly induced by (Bu)2cAMP stimulation. Interaction between this protein and a second factor, recognizing a purine-rich sequence between -53 and -46, partially overlapping the GC-box, is needed for the formation of the cAMP-induced DNA-protein complexes. A preformed complex between the cAMP-induced GC-box-binding factor and the second factor can be detected using nondenaturing conditions during Southwestern analysis.

Direct evidence that the mouse sex-determining gene Sry is expressed in the somatic cells of male fetal gonads and in the germ cell line in the adult testis

Reverse transcriptase polymerase chain reaction (RT-PCR) analysis shows that Sry mRNA is expressed in male fetal urogenital ridges from 12.5 day p.c. embryos, but not in enriched populations of primordial germ cells from the same embryos, indicating that Sry is expressed in the somatic cells of the embryonal gonad at the time of testis determination. We also show that, in the adult male mouse testis, Sry mRNA is expressed at high levels in meiotic and postmeiotic germ cells and, at much lower levels, also in Sertoli cells. Treatment with cyclic adenosine monophosphate (cAMP) analogs of cultured Sertoli cells from postnatal testis completely abolishes Sry mRNA expression.

Follicle-stimulating hormone induction of steel factor (SLF) mRNA in mouse Sertoli cells and stimulation of DNA synthesis in spermatogonia by soluble SLF

Follicle-stimulating hormone (FSH) and its intracellular mediator, cAMP, increase the mRNA levels for the Steel factor (SLF, the c-kit ligand) in cultured primary mouse Sertoli cells. The inductive effect of cAMP is more evident in cultures from 13-day-old animals than in cultures from 18-day-old animals. Analysis through the polymerase chain reaction (PCR) indicates that (Bu)2cAMP or FSH treatment increases the levels of the mRNAs for both the potentially soluble form and the transmembrane form of SLF in cultured Sertoli cells. The ratio between mRNAs encoding the potentially soluble form and the transmembrane form of SLF increases during postnatal testis development, and it is higher in cultured Sertoli cells with respect to total testis, suggesting that, under the in vitro conditions, SLF could be produced by Sertoli cells mainly as a soluble factor. Soluble recombinant SLF stimulates, in a dose-dependent fashion, thymidine incorporation in cultures of isolated germ cell populations enriched in the mitotic stages (spermatogonia), independently of the presence of serum, whereas cAMP analogs have no effect. Autoradiographic analysis shows that SLF selectively stimulates DNA synthesis in type A spermatogonia.

A novel c-kit transcript, potentially encoding a truncated receptor, originates within a kit gene intron in mouse spermatids

We have cloned a novel c-kit mRNA of 3.2 kb expressed in postmeiotic male germ cells. This transcript initiates in the genomic region immediately upstream of the exon coding for the second box of the split c-kit tyrosine kinase domain. The open reading frame (ORF) contains 12 novel amino acids in frame with the C-terminal 190 amino acids of the c-kit protein. It lacks therefore the upstream region in the 5.5-kb c-kit mRNA encoding the extracellular and transmembrane domain, the ATP-binding site and the kinase insert domain present in the c-kit protein.

Lens formation from the cornea following implantation into hindlimbs of larval Xenopus laevis: the influence of limb innervation and extent of differentiation

Corneal fragments of larval Xenopus laevis at stage 48 (according to Nieuwkoop and Faber, '56), were implanted into sham denervated unamputated hindlimbs, denervated unamputated hindlimbs, amputated and sham denervated hindlimbs, and amputated and denervated hindlimbs of larvae at stages 52 and 57. The results show that unamputated limbs at stage 52, either innervated or denervated, manifest a weak capacity to promote the first lens-forming transformations of the outer cornea. This capacity is absent in both limb types at stage 57. After amputation, limbs of both early and late stages form a regenerative blastema and support lens formation from the outer cornea. Denervation of early stage limbs has no appreciable effect on blastema formation and lens-forming transformation of corneal implants. However, denervation of late stage limbs inhibits both processes. These results indicate that the limb tissues of the early stage limbs contain non-neural inductive factors at a low level and that after limb amputation and blastema formation the level of these factors becomes high enough to promote lens formation from implanted cornea, even after denervation. In contrast, the limb tissues of late stage limbs do not contain a suitable level of non-neural inductive factors.

Expression of the mRNA for the ligand of c-kit in mouse Sertoli cells

The expression of the mRNA for SLF (the c-kit ligand), a product of the "steel" locus, has been investigated in postnatal mouse testis and homogeneous populations of testicular cells. The message was found expressed in postnatal mouse testis but not in germ cells. Studies on primary mouse Sertoli cell cultures from 18 day old mice show that Sertoli cells are the site of SLF mRNA expression in the seminiferous tubules. Treatment of Sertoli cell cultures with cAMP analogs led to a significant increase in the SLF mRNA levels.