Chemokine IP-10 expression in cultured human keratinocytes

The critical role of IFNγ in the epidermotropic migration of lymphocytes in oral lichen planus

INTRODUCTION

The chemokines play a crucial role in the recruitment of lymphocytes in oral lichen planus, and the activated epithelial cells are the main producers of the chemokines. However, the signals provoking chemokine secretion still remain to be elucidated.

METHODS

The global expression profile of chemokines in oral epithelial cell line induced by IFNγ was determined by microarray analysis. The gene and protein expression was validated in primary culture of oral epithelial cells, and the effects of IFNγ on regulating chemokine production were compared with that of TNFα and IL2. Moreover, the capability of primary culture of oral epithelial cells to attract peripheral lymphocytes in response to IFNγ was investigated in oral lichen planus patients, and the cell phenotype of the recruited lymphocytes was analyzed using flow cytometry.

RESULTS

IFNγ triggered the expression of multiple chemokines in the oral epithelial cells. The expression pattern of the chemokines closely resembled that in the epithelial cell layer of oral lichen planus lesions. Compared with IL2 and TNFα, IFNγ demonstrated a distinct maximal effect on the chemokines secretion in primary culture of oral epithelial cells. The migration of peripheral lymphocytes toward the culture supernatant of IFNγ-treated primary culture of oral epithelial cells was significantly enhanced in the oral lichen planus group compared to that in the healthy control group.

CONCLUSION

IFNγ plays an important role in the chemokine secretion and epidermotropic migration of lymphocytes in oral lichen planus.

CXCL10 and its related key genes as potential biomarkers for psoriasis: Evidence from bioinformatics and real-time quantitative polymerase chain reaction

Although several studies have attempted to investigate the etiology of and mechanism underlying psoriasis, the precise molecular mechanism remains unclear. Our study aimed to explore the molecular mechanism underlying psoriasis based on bioinformatics.GSE30999, GSE34248, GSE41662, and GSE50790 datasets were obtained from the Gene Expression Omnibus database. The Gene Expression Omnibus profiles were integrated to obtain differentially expressed genes in R software. Then a series of analyses was performed, such as Gene Ontology annotation, Kyoto Encyclopedia of Genes and Genomes pathway analysis, protein-protein interaction network analysis, among others. The key genes were obtained by CytoHubba, and validated by real-time quantitative polymerase chain reaction.A total of 359 differentially expressed genes were identified between 270 paired lesional and non-lesional skin groups. The common enriched pathways were nucleotide-binding and oligomerization domain-like receptor signaling pathway, and cytokine-cytokine receptor interaction. Seven key genes were identified, including CXCL1, ISG15, CXCL10, STAT1, OASL, IFIT1, and IFIT3. These key genes were validated as upregulated in the 4 datasets and M5-induced HaCaT cells.Our study identified 7 key genes, namely CXCL1, ISG15, CXCL10, STAT1, OASL, IFIT1, and IFIT3, and 2 mostly enriched pathways (nucleotide-binding and oligomerization domain-like receptor signaling pathway, and cytokine-cytokine receptor interaction) involved in psoriatic pathogenesis. More importantly, CXCL1, ISG15, STAT1, OASL, IFIT1, IFIT3, and especially CXCL10 may be potential biomarkers. Therefore, our findings may bring a new perspective to the molecular mechanism underlying psoriasis and suggest potential biomarkers.

SSeCKS/AKAP12 scaffolding functions suppress B16F10-induced peritoneal metastasis by attenuating CXCL9/10 secretion by resident fibroblasts

SSeCKS/Gravin/AKAP12 (SSeCKS) is a kinase scaffolding protein known to suppress metastasis by attenuating tumor-intrinsic PKC- and Src-mediated signaling pathways [1]. In addition to downregulation in metastatic cells, in silico analyses identified SSeCKS downregulation in prostate or breast cancer-derived stroma, suggesting a microenvironmental cell role in controlling malignancy. Although orthotopic B16F10 and SM1WT1[Braf^V600E] mouse melanoma tumors grew similarly in syngeneic WT or SSeCKS-null (KO) mice, KO hosts exhibited 5- to 10-fold higher levels of peritoneal metastasis, and this enhancement could be adoptively transferred by pre-injecting naïve WT mice with peritoneal fluid (PF), but not non-adherent peritoneal cells (PC), from naïve KO mice. B16F10 and SM1WT1 cells showed increased chemotaxis to KO-PF compared to WT-PF, corresponding to increased PF levels of multiple inflammatory mediators, including the Cxcr3 ligands, Cxcl9 and 10. Cxcr3 knockdown abrogated enhanced chemotaxis to KO-PF and peritoneal metastasis in KO hosts. Conditioned media from KO peritoneal membrane fibroblasts (PMF), but not from KO-PC, induced increased B16F10 chemotaxis over controls, which could be blocked with Cxcl10 neutralizing antibody. KO-PMF exhibited increased levels of the senescence markers, SA-β-galactosidase, p21^waf1 and p16^ink4a, and enhanced Cxcl10 secretion induced by inflammatory mediators, lipopolysaccharide, TNFα, IFNα and IFNγ. SSeCKS scaffolding-site mutants and small molecule kinase inhibitors were used to show that the loss of SSeCKS-regulated PKC, PKA and PI3K/Akt pathways are responsible for the enhanced Cxcl10 secretion. These data mark the first description of a role for stromal SSeCKS/AKAP12 in suppressing metastasis, specifically by attenuating signaling pathways that promote secretion of tumor chemoattractants in the peritoneum.

Tissue-specific regulation of CXCL9/10/11 chemokines in keratinocytes: Implications for oral inflammatory disease

The IFN-γ-inducible chemokines CXCL9, CXCL10, and CXCL11 play a key role in many inflammatory conditions, particularly those mediated by T cells. Therefore, the production of these chemokines in peripheral tissues could be instrumental in the pathophysiology of tissue-specific immunological diseases such as oral lichen planus (OLP). In the present study, we assessed the production of keratinocyte-derived CXCL9/10/11 under basal and inflammatory conditions and investigated whether these chemokines were involved in the pathogenesis of OLP. We used semi-quantitative PCR, ELISA, chemotaxis assays, and fluorescence-activated cell sorting (FACS) to assess the expression and functional role of CXCL9/10/11 in oral keratinocytes (three strains of normal human oral keratinocytes (NHOK), and the H357 oral cancer cell line) in the presence or absence of IFN-γ. CXCL9/10/11 were also assessed in tissues from normal patients and those with oral lichen planus (OLP). The time course study in oral keratinocytes treated with IFN-γ showed that expression of CXCL9/10/11 chemokines was significantly enhanced by IFN-γ in a time-dependent manner. In particular, CXCL10, a prominent chemokine that was overexpressed by IFN-γ-stimulated NHOK, was able to effectively recruit CD4 lymphocytes, mainly CD4+CD45RA- cells. Significantly higher levels of CXCL9/10/11 were found in tissues from patients with OLP compared to normal oral mucosa. Taken together, the results demonstrate that normal oral keratinocytes produce chemotactic molecules that mediate T cell recruitment. This study furthers understanding of chemokine production in oral keratinocytes and their role in the pathophysiology of oral mucosa, with particular relevance to OLP.

Psoriasis, Psoriatic Arthritis, and Thyroid Autoimmunity

Psoriasis (PsO) is a chronic relapsing/remitting autoimmune skin disease, associated with an increased risk of other autoimmune disorders. Psoriatic arthritis (PsA) is a chronic inflammatory arthritis occurring approximately in 30% of PsO patients. Sporadic cases of association between PsO and autoimmune thyroid disorders (AITDs) have been reported. However, two different recent studies did not find any association between them. In patients with PsO and PsA, an association with AITD has been shown by most of the studies in adults, but not in the juvenile form. In PsA women and men, thyroid autoimmunity [positive antithyroid peroxidase (AbTPO) antibodies, hypoechoic thyroid pattern] and subclinical hypothyroidism were more prevalent than in the general population. An association has been shown also in patients with PsO, arthritis, and inflammatory bowel disease, who have more frequently AITD. A Th1 immune predominance has been shown in early PsO, and PsA, with high serum CXCL10 (Th1 prototype chemokine), overall in the presence of autoimmune thyroiditis. This Th1 immune predominance might be the immunopathogenetic base of the association of these disorders. A raised incidence of new cases of hypothyroidism, thyroid dysfunction, positive AbTPO, and appearance of a hypoechoic thyroid pattern in PsA patients, especially in women, has been shown recently, suggesting to evaluate AbTPO levels, thyroid function, and thyroid ultrasound, especially in PsA women. Thyroid function follow-up and suitable treatments should be performed regularly in PsA female patients at high risk (thyroid-stimulating hormone within the normal range but at the higher limit, positive AbTPO, hypoechoic, and small thyroid).

Differential gene and protein expression of chemokines and cytokines in synovial fluid of patients with arthritis

Background

Psoriatic arthritis (PsA), an inflammatory musculoskeletal disease, develops in approximately 30% of patients with psoriasis. Previously, chemokine (C-X-C motif) ligand 10 (CXCL10) was identified as a predictive biomarker of PsA in patients with psoriasis and was reduced after development of PsA. The purpose of the present study was to explore messenger RNA (mRNA) and protein expression of CXCL10 and its receptor, chemokine (C-X-C motif) receptor 3 (CXCR3), in the joints of patients with PsA to gain insight into their role in the pathogenesis of the disease.

Methods

Sera from 47 patients with PsA and 33 healthy control subjects were compared for expression of CXCL10 by Luminex assay. Synovial fluid (SF) was obtained from patients with PsA (n = 40), osteoarthritis (OA; n = 14), gout (n = 8), and rheumatoid arthritis (RA; n = 11) during clinical care. SF mRNA and protein expression of CXCL10, interleukin-17A (IL-17A), CXCR3, TBX21, RORC and/or interferon γ (IFNγ) were compared among the above-mentioned disease groups, as well as in paired SF and serum samples from patients with PsA using real-time polymerase chain reaction and Luminex assays, respectively.

Results

Serum CXCL10 was significantly higher in patients with PsA than in control subjects (p = 0.0007). CXCL10, IL-17A, and TBX21 expression were elevated in SF cells of patients with PsA compared with those of patients with OA and gout, but not those of patients with RA. CXCR3 and RORC were elevated in PsA SF cells compared with all other patient groups. Concordant results were obtained for CXCL10 and IL-17A protein expression. IFNγ was elevated in PsA SF compared with OA SF (p = 0.015). CXCL10 protein expression was substantially increased in SF (median 7283.9 pg/ml, interquartile range [IQR] 1330–10,362 pg/ml) compared with paired serum samples (median 282.06, IQR 180.7–395.8 pg/ml; p = 0.001), whereas IFNγ was significantly reduced (SF median 6.03 pg/ml, IQR 4.47–8.94 pg/ml; versus serum median 23.70 pg/ml, IQR 3.2–104.6 pg/ml; p = 0.001).

Conclusions

CXCL10 may have an important etiological role in PsA that is analogous to that in RA, and it is a candidate biomarker to distinguish PsA from healthy individuals and from patients with OA and gout.

Antimicrobial activity and regulation of CXCL9 and CXCL10 in oral keratinocytes

Chemokine (C-X-C motif) ligand (CXCL)9 and CXCL10 are dysregulated in oral inflammatory conditions, and it is not known if these chemokines target microorganisms that form oral biofilm. The aim of this study was to investigate the antimicrobial activity of CXCL9 and CXCL10 on oral microflora and their expression profiles in oral keratinocytes following exposure to inflammatory and infectious stimuli. Streptococcus sanguinis was used as a model and Escherichia coli as a positive control. The antimicrobial effect of CXCL9/CXCL10 was tested using a radial diffusion assay. mRNA transcripts were isolated from lipopolysaccharide (LPS)-treated and untreated (control) oral keratinocyte cell lines at 2-, 4-, 6-, and 8-h time-points of culture. The CXCL9/10 expression profile in the presence or absence of interferon-γ (IFN-γ) was assessed using semiquantitative PCR. Although both chemokines demonstrated antimicrobial activity, CXCL9 was the most effective chemokine against both S. sanguinis and E coli. mRNA for CXCL10 was expressed in control cells and its production was enhanced at all time-points following stimulation with LPS. Conversely, CXCL9 mRNA was not expressed in control or LPS-stimulated cells. Finally, stimulation with IFN-γ enhanced basal expression of both CXCL9 and CXCL10 in oral keratinocytes. Chemokines derived from oral epithelium, particularly CXCL9, demonstrate antimicrobial properties. Bacterial and inflammatory-stimulated up-regulation of CXCL9/10 could represent a key element in oral bacterial colonization homeostasis and host-defense mechanisms.

CXCL10 in psoriasis

Chemokine (C-X-C motif) ligand (CXCL)10 is involved in the pathogenesis of psoriasis. It has been demonstrated that chemokine (C-X-C motif) receptors (CXCR)3 and CXCL10 were detected in keratinocytes and the dermal infiltrate obtained from active psoriatic plaques and that successful treatment of active plaques decreased the expression of CXCL10. Elevated CXCL10 serum levels have been shown in patients with psoriasis, with a type 1 T helper cells immune predominance at the beginning of the disease, while a decline of this chemokine has been evidenced later, in long lasting psoriasis. Circulating CXCL10 is significantly higher in patients with psoriasis in the presence of autoimmune thyroiditis. It has been hypothesized that CXCL10 could be a good marker to monitor the activity or progression of psoriasis. Efforts have been made to modulate or inhibit the CXCR3/CXCL10 axis in psoriasis to modify the course of the disease.

Human B cells produce chemokine CXCL10 in the presence of Mycobacterium tuberculosis specific T cells

BACKGROUND

The role of B cells in human host response to Mycobacterium tuberculosis (Mtb) infection is still controversial, but recent evidence suggest that B cell follicle like structures within the lung may influence host responses through regulation of the local cytokine environment. A candidate for such regulation could be the chemokine CXCL10. CXCL10 is mainly produced by human monocytes, but a few reports have also found CXCL10 production by human B cells. The objective of this study was to investigate CXCL10 production by human B cells in response to in vitro stimulation with Mtb antigens.

METHODOLOGY/PRINCIPAL FINDINGS

We analyzed human blood samples from 30 volunteer donors using multiparameter flow cytometry, and identified a subgroup of B cells producing CXCL10 in response to in vitro stimulation with antigens. T cells did not produce CXCL10, but CXCL10 production by B cells appeared to be mediated via IFN-γ and dependent on contact with antigen-specific T cells recognizing the antigen.

CONCLUSION

Human B cells are able to produce CXCL10 in an IFN-γ and T cell contact-dependent manner. The present findings suggest a possible mechanism through which B cells in part may influence granuloma formation in human tuberculosis (TB) and participate in infection control.

Moutan Cortex Radicis inhibits inflammatory changes of gene expression in lipopolysaccharide-stimulated gingival fibroblasts

Moutan Cortex Radicis (MCR), the root bark of Paeonia suffruticosa Andrews (Paeoniaceae), is found in the traditional Chinese medicinal formulae which were used to treat periodontal diseases. This study investigated the changes in gene expression by MCR treatment when stimulated with lipopolysaccharide (LPS) in cultured human gingival fibroblasts (HGFs). A genome-wide expression GeneChip was used for the gene array analysis, and real-time reverse transcription polymerase chain reaction (RT-PCR) analysis was also performed to confirm the gene expression. It was shown that 42 of the 643 genes up-regulated by LPS, when compared to the control, were down-regulated by the MCR treatment. Of these 42 genes, the inflammation and immune response-related genes were especially noted, which indicates that MCR inhibits the induction of inflammation by LPS stimulation. In addition, 33 of the 519 genes down-regulated by LPS, when compared to the control, were up-regulated by the MCR treatment. The expression patterns of some representative genes by real-time RT-PCR correlated with those of the genes shown in the microarray. In addition, the MCR extract contained paeonol and paeoniflorin, which are known to have the anti-inflammatory effect as the major phenolic components of MCR. This study showed that the MCR extract could comprehensively inhibit a wide variety of activations of inflammation-related genes, which may be due to paeonol and paeoniflorin. It is, thus, suggested that MCR may be applied to alleviate the inflammation of periodontal diseases.

Type 2 helper T-cell cytokines induce morphologic and molecular characteristics of atopic dermatitis in human skin equivalent

Both the immune system and the epidermis likely have an important role in the pathogenesis of atopic dermatitis (AD). The objective of the present study was to develop a human skin equivalent model exhibiting morphologic and molecular characteristics of AD in a controlled manner. Skin equivalents generated from normal adult human keratinocytes were stimulated with type 2 T-helper cell (Th2) cytokines IL-4 and IL-13, and morphologic features and gene expression of the epidermis were studied. Th2 cytokines induced intercellular edema similar to spongiotic changes observed in lesional AD as assessed at histopathologic analysis and electron microscopy. Furthermore, genes known to be specifically expressed in epidermis of patients with AD such as CAII and NELL2 were induced. In contrast, expression of psoriasis-associated genes such as elafin and hBD2 was not changed. Th2 cytokines caused DNA fragmentation in the keratinocytes, which could be inhibited by the caspase inhibitor Z-VAD, which suggests that apoptosis was induced. In addition, up-regulation of the death receptor Fas was observed in keratinocytes after Th2 cytokine stimulation. IL-4 and IL-13 induced phosphorylation of the signaling molecule STAT6. It was concluded that the skin equivalent model described herein may be useful in investigation of the epidermal aspects of AD and for study of drugs that act at the level of keratinocyte biology.

TNFα and IFNγ synergistically enhance transcriptional activation of CXCL10 in human airway smooth muscle cells via STAT-1, NF-κB, and the transcriptional coactivator CREB-binding protein

Asthmatic airway smooth muscle (ASM) expresses interferon-γ-inducible protein-10 (CXCL10), a chemokine known to mediate mast cell migration into ASM bundles that has been reported in the airways of asthmatic patients. CXCL10 is elevated in patients suffering from viral exacerbations of asthma and in patients with chronic obstructive pulmonary disease (COPD), diseases in which corticosteroids are largely ineffective. IFNγ and TNFα synergistically induce CXCL10 release from human ASM cells in a steroid-insensitive manner, via an as yet undefined mechanism. We report that TNFα activates the classical NF-κB (nuclear factor κB) pathway, whereas IFNγ activates JAK2/STAT-1α and that inhibition of the JAK/STAT pathway is more effective in abrogating CXCL10 release than the steroid fluticasone. The synergy observed with TNFα and IFNγ together, however, did not lie at the level of NF-κB activation, STAT-1α phosphorylation, or in vivo binding of these transcription factors to the CXCL10 promoter. Stimulation of human ASM cells with TNFα and IFNγ induced histone H4 but not histone H3 acetylation at the CXCL10 promoter, although no synergism was observed when both cytokines were combined. We show, however, that TNFα and IFNγ exert a synergistic effect on the recruitment of CREB-binding protein (CBP) to the CXCL10, which is accompanied by increased RNA polymerase II. Our results provide evidence that synergism between TNFα and IFNγ lies at the level of coactivator recruitment in human ASM and suggest that inhibition of JAK/STAT signaling may be of therapeutic benefit in steroid-resistant airway disease.

Influence of apple polyphenols on inflammatory gene expression

Apples (Malus spp., Rosaceae) and products thereof contain high amounts of polyphenols which show diverse biological activities and may contribute to beneficial health effects, like protecting the intestine against inflammation initiated by chronic inflammatory bowel diseases (IBD). IBD are characterized by an excessive release of several proinflammatory cytokines and chemokines by different cell types which results consequently in an increased inflammatory response. In the present study we investigated the preventive effectiveness of polyphenolic juice extracts and single major constituents on inflammatory gene expression in immunorelevant human cell lines (DLD-1, T84, MonoMac6, Jurkat) induced with specific stimuli. Besides the influence on proinflammatory gene expression, the effect on NF-kappaB-, IP-10-, IL-8-promoter-, STAT1-dependent signal transduction, and the relative protein levels of multiple released cytokines and chemokines were studied. DNA microarray analysis of several genes known to be strongly regulated during gastrointestinal inflammation, combined with quantitative real-time PCR (qRT-PCR) revealed that the apple juice extract AE04 (100-200 microg/mL) significantly inhibited the expression of NF-kappaB regulated proinflammatory genes (TNF-alpha, IL-1beta, CXCL9, CXCL10), inflammatory relevant enzymes (COX-2, CYP3A4), and transcription factors (STAT1, IRF1) in LPS/IFN-gamma stimulated MonoMac6 cells without significant effects on the expression of house-keeping genes. A screening of some major compounds of AE04 revealed that the flavan-3-ol dimer procyanidin B(2 )is mainly responsible for the anti-inflammatory activity of AE04. Furthermore, the dihydrochalcone aglycone phloretin and the dimeric flavan-3-ol procyanidin B(1 )significantly inhibited proinflammatory gene expression and repressed NF-kappaB-, IP-10-, IL-8-promoter-, and STAT1-dependent signal transduction in a dose-dependent manner. The influence on proinflammatory gene expression by the applied polyphenols thereby strongly correlated with the increased protein levels investigated by human cytokine array studies. In summary, we evaluated selected compounds responsible for the anti-inflammatory activity of AE04. In particular, procyanidin B(1), procyanidin B(2), and phloretin revealed anti-inflammatory activities in vitro and therefore may serve as transcription-based inhibitors of proinflammatory gene expression.

Etanercept treatment reduces the serum levels of interleukin-15 and interferon-gamma inducible protein-10 in patients with rheumatoid arthritis

Tumor necrosis factor-alpha (TNF-alpha) has an essential role in the pathogenesis of rheumatoid arthritis (RA) and has been known to induce the production of several inflammatory molecules in vivo. To analyze in vivo the active mechanism of the TNF-alpha blocking agent, etanercept, the serum levels of the cytokine interleukin-15 (IL-15) and the chemokines growth-regulated protein-alpha (Gro-alpha), and interferon-gamma inducible protein-10 (IP-10) in RA patients were measured. Twenty-two patients with RA were administered etanercept once or twice a week for more than 6 months. The clinical and laboratory parameters were measured and serum levels of IL-15, Gro-alpha, and IP-10 were determined using enzyme-linked immunosorbent assay (ELISA) kits at the baseline and at 3 and 6 months after the initial treatment. Additionally, the production of IL-15 and IP-10 by cultured synovial cells stimulated with TNF-alpha from RA patients was determined by ELISA. A significant decrease in serum levels of IL-15 and IP-10 was observed at 3 and 6 months after initial treatment with etanercept, but not in those of Gro-alpha. TNF-alpha induced production of IP-10, but not IL-15 in cultured synovial cells from RA patients. This study demonstrated for the first time the reduction of IP-10 and IL-15 production in RA patients as active mechanisms of etanercept.

Mycobacterium bovis Bacillus Calmette-Guérin (BCG)-induced activation of PI3K/Akt and NF-kB signaling pathways regulates expression of CXCL10 in epithelial cells

CXCL10 production is a critical step in limiting mycobacterial infection. Although induction of this chemokine by mycobacteria in epithelial cells has been reported, it is still unclear how CXCL10 is regulated in Mycobacterium bovis BCG-infected epithelial cells. In this study, we demonstrate that phosphatidylinoditol 3-kinase (PI3K)/Akt and the nuclear factor kB (NF-kB) signaling pathways play an important role in CXCL10 expression at the protein and mRNA level in A549 cells. We demonstrate that treatment of A549 cells with LY294002 and wortmannin, two PI3K inhibitors, inhibited M. bovis BCG-induced CXCL10 expression. In addition, treatment of A549 cells with an Akt inhibitor significantly blocked M. bovis BCG-induced CXCL10 production. Moreover, our data show that treatment of epithelial cells with CAPE, BAY 11-7082, and PDTC three selective inhibitors of NF-kB, significantly reduced the effect of M. bovis BCG on induced CXCL10 mRNA expression (74%, 69% and 83% inhibition by 8microM CAPE, 10microM BAY 11-7082 and 3microM PDTC as assessed by real-time PCR, respectively). In accordance with the gene induction, the production of CXCL10 was also significantly reduced by these inhibitors. Finally, the inhibition of PI3K affect NF-kB activation in M. bovis BCG-infected cells, indicating that PI3K activity is required for the M. bovis BCG-induced activation of NF-kB. The functional association between PI3K/Akt and NF-kB demonstrates another mechanism in the regulation of M. bovis BCG-induced CXCL10 in A549 cells.

Regulation of CXCL9/10/11 in Oral Keratinocytes and Fibroblasts

Th1 and Th2 cytokines such as interferon-γ (IFN-γ ) , tumor necrosis factor- α (TNF-α ), and IL-4 are expressed in T-cell-mediated inflammation in the oral cavity. We tested the hypothesis that those cytokines may act on CXCR3-agonistic chemokines, T-cell recruiting factors, and on neighboring cells, including oral keratinocytes and fibroblasts. Human immortalized oral keratinocytes (RT7) and fibroblasts (GT1) after 24-hour stimulation with IFN-γ showed increased mRNA levels of CXCL9 (600- and 700-fold), CXCL10 (10,000- and 150-fold), and CXCL11 (5000- and 300-fold), respectively. In contrast, TNF-α caused an increase in CXCL9 (300-fold), CXCL10 (2000-fold), and CXCL11 (2000-fold) mRNA levels in GT1, but not RT7 cells, at 24 hrs. IL-4 reinforced the promotion of CXCL9, CXCL10, and CXCL11 expression by IFN-γ in RT7 cells, whereas IL-4 inhibited the increased levels by IFN-γ and TNF-α in GT1 cells. Thus, IFN-γ , TNF-α , and IL-4 appear cooperatively to regulate CXCR3-agonistic chemokines in oral keratinocytes and fibroblasts in T-cell-mediated oral inflammation sites.

NF-kappaB-dependent synergistic regulation of CXCL10 gene expression by IL-1beta and IFN-gamma in human intestinal epithelial cell lines

BACKGROUND AND AIMS

Little is known about the intestinal epithelial expression and secretion of CXCL10 (IP-10), a chemokine involved in recruiting T cells and monocytes. We aimed to study CXCL10 gene expression and regulation by the pro-inflammatory cytokines interleukin (IL)-1beta, interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha in intestinal epithelial cell lines.

MATERIALS AND METHODS

CXCL10 expression and secretion kinetics were assessed in Caco-2, HT-29 and DLD1 human colon epithelial cells, treated with IL-1beta, TNF-alpha, IFN-gamma alone or in combination with each other by real-time polymerase chain reaction (PCR), Northern blotting and enzyme-linked immunoabsorbent assay (ELISA). Transient transfections with TGL-IP10 (CXCL10 promoter) and TGL-IP10-kappaB2 mutant promoter and gelshifts and supershifts for nuclear factor (NF)-kappaB were also performed.

RESULTS

Real-time PCRs and ELISA experiments revealed that IL-1beta was the strongest and earliest inducer of CXCL10 messenger ribonucleic acid (mRNA) expression and protein secretion in Caco-2 cell line, whereas INF-gamma had a delayed kinetics. There was a strong synergistic effect of either TNF-alpha or IL-1beta with IFN-gamma both on CXCL10 mRNA expression and protein secretion in all three cell lines. Real-time PCR and ELISA experiments using a specific NF-kappaB inhibitor and transfection experiments with a NF-kappaB-binding defective CXCL10 promoter construct revealed that the induction of CXCL10 by IL-1beta and its synergism with IFN-gamma is NF-kappaB dependent.

CONCLUSION

These data demonstrate that in colonic epithelial cells, depending on the cellular context and utilizing the NF-kappaB pathway, IL-1beta alone and/or in synergism with IFN-gamma may play a major role in the induction of CXCL10.

Epidermal chemokines and modulation by antihistamines, antibiotics and antifungals

Growing evidence has demonstrated that chemokines released from epidermal cells control inflammatory skin diseases. Keratinocytes elaborate both Th1- and Th2-associated chemokines, although the former is more abundantly produced than the latter. Downmodulation of keratinocyte production of chemokines is one of the therapeutic approaches for cutaneous inflammatory disorders. Recent observations have shown that keratinocyte chemokine production can be modulated by well-used drugs, including antihistamines, antibiotics and antifungals. Utilization of the beneficial side effects of these drugs may by clinically valuable.

The IL-17F signaling pathway is involved in the induction of IFN-gamma-inducible protein 10 in bronchial epithelial cells

BACKGROUND

IL-17F is involved in airway inflammation, but its biologic activity and signaling pathway remain incompletely defined. Interferon-gamma-inducible protein 10 (IP-10) is widely expressed and plays a role in airway inflammatory diseases.

OBJECTIVE

We sought to investigate the functional linkage between IL-17F and IP-10 expression in bronchial epithelial cells.

METHODS

Bronchial epithelial cells were cultured in the presence or absence of IL-17F, and/or a T(H)1 cytokine, T(H)2 cytokines, proinflammatory cytokines, various kinase inhibitors, or a Raf1 dominant-negative mutant to analyze the expression of IP-10. Moreover, the involvement of p90 ribosomal S6 kinase (p90RSK) and cyclic AMP response element-binding protein (CREB) in IL-17F-induced IP-10 expression were investigated.

RESULTS

IL-17F induces the gene and protein expression of IP-10. The addition of IFN-gamma, IL-1beta, and TNF-alpha augmented IL-17F-induced IP-10 expression. The mitogen-activated protein kinase kinase (MEK) inhibitors PD98059, U0126, and Raf1 kinase inhibitor I significantly inhibited its production. In contrast, a p38 inhibitor, a JNK inhibitor, protein kinase C inhibitors, and a phosphatidylinositol 3-kinase inhibitor, showed no inhibitory effect. Furthermore, overexpression of a Raf1 dominant-negative mutant inhibited its expression. Of interest, IL-17F phosphorylated p90RSK and CREB, and transfection of the cells with a short interfering RNA for p90RSK or CREB inhibited its expression, suggesting p90RSK and CREB as novel signaling molecules of IL-17F.

CONCLUSION

IL-17F is a potent inducer of IP-10 in bronchial epithelial cells through the activation of the Raf1-MEK1/2-extracellular signal-regulated kinase 1/2-p90RSK-CREB pathway, supporting its regulatory role in airway inflammation.

CLINICAL IMPLICATIONS

The IL-17F-IP-10 axis might be a novel and critical therapeutic target for airway inflammatory diseases.

An Anti-IL-12p40 Antibody Down-Regulates Type 1 Cytokines, Chemokines, and IL-12/IL-23 in Psoriasis

Psoriasis is characterized by activation of T cells with a type 1 cytokine profile. IL-12 and IL-23 produced by APCs are essential for inducing Th1 effector cells. Promising clinical results of administration of an Ab specific for the p40 subunit of IL-12 and IL-23 (anti-IL-12p40) have been reported recently. This study evaluated histological changes and mRNA expression of relevant cytokines and chemokines in psoriatic skin lesions following a single administration of anti-IL-12p40, using immunohistochemistry and real-time RT-PCR. Expression levels of type 1 cytokine (IFN-gamma) and chemokines (IL-8, IFN-gamma-inducible protein-10, and MCP-1) were significantly reduced at 2 wk posttreatment. The rapid decrease of these expression levels preceded clinical response and histologic changes. Interestingly, the level of an anti-inflammatory cytokine, IL-10, was also significantly reduced. Significant reductions in TNF-alpha levels and infiltrating T cells were observed in high responders (improvement in clinical score, > or =75% at 16 wk), but not in low responders. Of importance, the levels of APC cytokines, IL-12p40 and IL-23p19, were significantly decreased in both responder populations, with larger decreases in high responders. In addition, baseline levels of TNF-alpha significantly correlated with the clinical improvement at 16 wk, suggesting that these levels may predict therapeutic responsiveness to anti-IL-12p40. Thus, in a human Th1-mediated disease, blockade of APC cytokines by anti-IL-12p40 down-regulates expression of type 1 cytokines and chemokines that are downstream of IL-12/IL-23, and also IL-12/IL-23 themselves, with a pattern indicative of coordinated deactivation of APCs and Th1 cells.

Targeted in vivo expression of IFN-gamma-inducible protein 10 induces specific antitumor activity

Although it is known that the chemoattractant effect of IFN-gamma inducible protein 10 (IP-10), a CXC chemokine (CXCL10), plays an important role in T cell-mediated antitumor immunity in vivo, whether IP-10 is involved in modulating the proliferation, survival and functional activation of tumor-specific T cells remains poorly investigated. Using an experimental mouse tumor model, we demonstrated that the in vivo growth of 4T1 tumor cells harboring IP-10 gene (4T1-IP-10) was inhibited. Mice inoculated with 4T1-IP-10 tumor cells expressing functional IP-10 survived over 90 days, whereas mice injected with control parental 4T1 cells and mice of control 4T1 cells transduced with control plasmid all succumbed to the tumor by day 38 after tumor inoculation. Mechanical analysis showed that targeted expression of IP-10 in 4T1 tumor cells markedly enhanced the infiltration of tumor-specific T cells into the 4T1-IP-10 tumor. These tumor infiltrating T lymphocytes (TILs) recruited by IP-10 were potent cytolytic killers against 4T1 tumor cells and were able to proliferate and produce high levels of IFN-gamma in response to 4T1 cells. In vivo administration of IP-10-recruited TILs induced vigorous proliferation of these TILs in situ in the 4T1-IP-10 tumor but not in the 4T1-pcDNA3 and parental 4T1 tumors. Furthermore, culture of TILs together with recombinant IP-10 significantly enhanced the proliferation and expansion of IP-10-recruited TILs in response to 4T1 tumor antigens. These results suggest that IP-10 is not only able to chemoattract tumor-specific T cells into the local tissue, but also enhance the proliferation, survival, and functional activation of these TILs, leading to the tumor regression. Thus, targeted expression of IP-10 in vivo will allow for the development of a novel approach for immunotherapy of tumor.

The Selective Protein Kinase C β Inhibitor Enzastaurin Induces Apoptosis in Cutaneous T-Cell Lymphoma Cell Lines through the AKT Pathway

Enzastaurin displays pro-apoptotic properties against a spectrum of malignancies and is currently being investigated in clinical trials. We have investigated the effects of enzastaurin on the viability of the cutaneous T-cell lymphoma cell lines HuT-78 and HH by using 3-(4,5-dimethylthiazol-2-yl)-5(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay, cell cycle analysis, propidium iodide and annexin-V staining, and caspase-3-mediated proteolytic activation. Enzastaurin-treatment decreased cell viability, increased annexin V-FITC-positive cells, and increased the proportion of sub-G1 populations in both cell lines that was not reversed by the T-cell growth stimulating cytokines IL-2, IL-7, IL-15. Enzastaurin-induced cell death involved caspase-3-activated cleavage of poly(ADP-ribose) polymerase that was inhibited by the pan-caspase inhibitor ZVAD-fmk, whereas the increase in sub-G1 population was only partially inhibited by ZVAD-fmk. Furthermore, enzastaurin downregulated AKT activity and its downstream effectors GSK3beta and ribosomal protein S6. The phosphatidylinositol 3-kinase (PI3K)/AKT pathway has been implicated in the growth and survival of hematologic malignancies and inhibition of this pathway is considered as a therapeutic target. Protein kinase C activation contributes to PI3K/AKT activation, but it is unknown how enzastaurin may interfere with signaling through this pathway. These results demonstrate that enzastaurin, at clinically achievable concentrations, induces apoptosis and affects AKT signaling, and provide a rationale for further in vivo studies addressing the therapeutic efficacy in cutaneous T-cell lymphoma patients.

Human Keratinocytes Respond to Interleukin-18: Implication for the Course of Chronic Inflammatory Skin Diseases

Interleukin (IL)-18 has been described to play a role in several inflammatory skin diseases such as eczema and psoriasis. In this study, we aimed to elucidate keratinocytes as potential targets for IL-18 effects. In human primary keratinocytes expression of IL-18Ralpha as well as responses to IL-18 were determined. In keratinocytes freshly isolated from skin biopsies of lesional atopic dermatitis or psoriasis, we observed a significantly higher expression of the IL-18Ralpha as compared with keratinocytes from normal donors. A marked upregulation was induced in vitro upon stimulation with interferon (IFN)gamma+tumor necrosis factor (TNF)alpha or poly I:C. IL-4 led to downregulation of IL-18Ralpha. IL-18-induced CXCL10/IP-10 production in freshly isolated keratinocytes from lesional psoriasis as well as in cultured normal keratinocytes. Furthermore, IL-18 upregulated major histocompatibility complex (MHC) class II expression on IFNgamma-stimulated keratinocytes. This was of functional significance as verified in coculture experiments with CD4+ T cells in the presence of superantigen. T cells produced significant amounts of IFNgamma after coculture with IL-18-induced MHC class II expressing keratinocytes. In conclusion, we have shown that keratinocytes functionally respond to IL-18 with upregulation of MHC II and production of the chemokine CXCL10/IP-10. These findings further support an important role of IL-18 in inflammatory skin diseases in the epidermal compartment.

Identification of genes differentially expressed in T cells following stimulation with the chemokines CXCL12 and CXCL10

BACKGROUND

Chemokines are involved in many biological activities ranging from leukocyte differentiation to neuronal morphogenesis. Despite numerous reports describing chemokine function, little is known about the molecular changes induced by cytokines.

METHODS

We have isolated and identified by differential display analysis 182 differentially expressed cDNAs from CXCR3-transfected Jurkat T cells following treatment with CXCL12 or CXCL10. These chemokine-modulated genes were further verified using quantitative RT-PCR and Western blot analysis.

RESULTS

One hundred and forty-six of the cDNAs were successfully cloned, sequenced, and identified by BLAST. Following removal of redundant and non-informative clones, seventeen mRNAs were found to be differentially expressed post treatment with either chemokine ligand with several representing known genes with established functions. Twenty-one genes were upregulated in these transfected Jurkat cells following both CXCL12 and CXCL10, four genes displayed a discordant response and seven genes were downregulated upon treatment with either chemokine. Identified genes include geminin (GEM), thioredoxin (TXN), DEAD/H box polypeptide 1 (DDX1), growth hormone inducible transmembrane protein (GHITM), and transcription elongation regulator 1 (TCERG1). Subsequent analysis of several of these genes using semi-quantitative PCR and western blot analysis confirmed their differential expression post ligand treatment.

CONCLUSIONS

Together, these results provide insight into chemokine-induced gene activation and identify potentially novel functions for known genes in chemokine biology.

Roxithromycin downmodulates Th2 chemokine production by keratinocytes and chemokine receptor expression on Th2 cells: its dual inhibitory effects on the ligands and the receptors

Roxithromycin (RXM), an anti-bacterial macrolide, has various immunomodulatory activities. To investigate the ability of RXM to downregulate skin-infiltration of T-lymphocytes, we examined the effects of RXM on keratinocyte production of chemokines and T cell expression of chemokine receptors. Normal human and HaCaT keratinocytes were cultured with RXM and stimulants. RXM at 1 or 10 microM significantly suppressed the production/expression of Th2 chemokines MDC and TARC in these keratinocytes, but the production of IP-10 was not affected. The effect of RXM on T-cell expression of the corresponding chemokine receptors was also tested in Th2-rich peripheral blood lymphocytes. The IL-2-enhanced expression level of Th2 chemokine receptor CCR4 was decreased by RXM at 10 microM, whereas the expression of CXCR3 was unchanged. Thus, RXM downmodulates both the production and receptor expression of Th2 but not Th1 chemokines involved in cutaneous immunity, suggesting its beneficial therapeutic effects on Th2-mediated or allergic skin disorders.

Regulation of TNF‐α and IFN‐γ induced CXCL10 expression: participation of the airway smooth muscle in the pulmonary inflammatory response in chronic obstructive pulmonary disease

The chemokine CXCL10 is produced by many inflammatory cells found in the diseased lung and has been implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD). The present study demonstrates elevated CXCL10 protein in the lungs of COPD patients, which appears histologically in airway smooth muscle (hASM). In primary cultured hASM cells taken from normal donors, CXCL10 protein expression was induced by IFN-gamma and TNF-alpha, cytokines reported as elevated in COPD, and a synergistic response was obtained when they were combined. TNF-alpha stimulation of hASM enhanced accumulation of CXCL10 mRNA, indicating regulation at the transcriptional level, while IFN-gamma stimulation resulted in a smaller accumulation of CXCL10 mRNA. When these cytokines were applied simultaneously, an additive effect was obtained. TNF-alpha-induced CXCL10 expression in hASM was dependent on NFkappaB activation, and a salicylanilide NFkappaB inhibitor blocked the CXCL10 expression. In contrast, IFN-gamma stimulation resulted in transient NFkappaB activation, and the inhibitor had little effect on CXCL10 expression. When these cytokines were added simultaneously, NFkappaB was activated earlier and lasted longer, and the effect was blocked by the inhibitor. These data demonstrate a potential active role for hASM in pulmonary inflammatory diseases such as COPD by producing CXCL10.

Expression of the chemokine IP-10 (CXCL10) by hepatocytes in chronic hepatitis C virus infection correlates with histological severity and lobular inflammation

The factors influencing lymphocyte trafficking to the liver lobule during chronic hepaititis C virus (HCV) infection are currently not well defined. Interferon-gamma-inducible protein 10 (IP-10), a chemokine that recruits activated T lymphocytes, has recently been shown by in situ hybridization to be expressed in the liver during chronic HCV infection. This study sought to define the cellular source of IP-10 in the liver by immunohistochemistry, to examine the expression of its receptor, CXCR3, on T lymphocytes isolated from blood and liver tissue, and to correlate IP-10 expression with the histological markers of inflammation and fibrosis. IP-10 was expressed by hepatocytes but not by other cell types within the liver, and the most intense immunoreactivity was evident in the areas of lobular inflammation. The IP-10 receptor was expressed on a significantly higher proportion of T lymphocytes in the liver compared with blood. CD8 T lymphocytes, which predominate in the liver lobule, were almost uniformly CXCR3-positive. The expression of IP-10 mRNA correlated with lobular necroinflammatory activity but not with inflammation or fibrosis in the portal tracts. These findings suggest that IP-10 may be induced by HCV within hepatocytes and may be important in the pathogenesis of chronic HCV infection, as recruitment of inflammatory cells into the lobule is an important predictor of disease progression.

The inhibitory effect of VitD3 on proliferation of keratinocyte cell line HACAT is mediated by down-regulation of CXCR2 expression

Psoriasis is a disease characterized by inflammation and increased population of hyperproliferative keratinocytes. It is well known that chemokines and chemokine receptors, such as interleukin-8 and its receptors (CXCR1 and CXCR2), play important roles in the pathogenesis of psoriasis. So far, examination of CXCR2 expression in psoriatic lesional keratinocytes by FACS calibur has not been reported and whether VitD3 inhibits psoriatic lesional keratinocyte proliferation through down-regulation of CXCR2 expression has not been elucidated. In the present study, CXCR2 expression in psoriatic lesional keratinocytes and HACAT treated with VitD3 was detected by flow cytometry. The proliferative capacity of HACAT treated with VitD3 was assayed by MTT assay. The results showed that CXCR2 expression in psoriatic lesional keratinocytes was higher than that in normal human keratinocytes. At the correct concentration VitD3 could inhibit human keratinocyte proliferation and down-regulate CXCR2 expression in HACAT. The data demonstrate that the inhibitory effect of VitD3 on keratinocyte proliferation might be mediated by down-regulation of CXCR2 expression.

17beta-estradiol inhibits the production of interferon-induced protein of 10 kDa by human keratinocytes

The natural course of psoriasis is often modulated during pregnancy, indicating the regulatory effect of estrogen or progesterone on psoriasis. Interferon-induced protein of 10 kDa chemoattracts T helper 1 cells, and interferon-induced protein of 10 kDa production by keratinocytes is enhanced in psoriatic skin lesions. We examined in vitro effects of sex hormones on the interferon-induced protein of 10 kDa production by human keratinocytes. 17beta-estradiol inhibited interferon-gamma-induced interferon-induced protein of 10 kDa secretion, mRNA expression, and promoter activity. Interferon-stimulated response element on the promoter was responsible for the inhibition by 17beta-estradiol. Interferon-gamma-induced protein of 10 kDa production was also inhibited by anti-estrogens, ICI 182 780 and tamoxifen, and membrane-impermeable bovine serum albumin-conjugated 17beta-estradiol, suggesting the effects via membrane estrogen receptor, whereas 17alpha-estradiol, progesterone, and dihydrotestosterone had no effects. 17beta-estradiol and bovine serum albumin-conjugated 17beta-estradiol suppressed interferon-gamma-induced transcription through the interferon-stimulated response element and signal transducer and activator of transcription 1alpha binding to interferon-stimulated response element. 17beta-estradiol and bovine serum albumin-conjugated 17beta-estradiol suppressed interferon-gamma-induced tyrosine phosphorylation of signal transducer and activator of transcription 1alpha, and Janus tyrosine kinase 1 and 2. 17beta-estradiol-mediated suppression on the interferon-gamma-induced signal transducer and activator of transcription 1alpha activation and interferon-induced protein of 10 kDa synthesis was counteracted by adenylate cyclase inhibitor SQ22536. 17beta-estradiol, bovine serum albumin-conjugated 17beta-estradiol, ICI 182 780, and tamoxifen increased intracellular 3',5'-adenosine cyclic monophosphate level by activating adenylate cyclase in keratinocytes. Fluorescein isothiocyanate-labeled bovine serum albumin-conjugated 17beta-estradiol bound to the surface of keratinocytes, and mRNA for estrogen receptor beta but not for estrogen receptor alpha was detected in keratinocytes. These results suggest that 17beta-estradiol may interact with the membrane receptor on keratinocytes and generate 3',5'-adenosine cyclic monophosphate by activating adenylate cyclase, which may lead to the inhibition of interferon-gamma-induced signal transducer and activator of transcription 1alpha activation and interferon-induced protein of 10 kDa synthesis.

Substance P enhances the production of interferon-induced protein of 10 kDa by human keratinocytes in synergy with interferon-gamma

A neuropeptide substance P is related to skin inflammation. Interferon-induced protein of 10 kDa (IP-10) chemoattracts T helper 1 cells, and interferon-induced protein of 10 kDa production by keratinocytes is enhanced in inflammatory skin diseases such as psoriasis. We examined the in vitro effects of substance P on interferon-induced protein of 10 kDa production by human keratinocytes. Though substance P alone did not induce interferon-induced protein of 10 kDa production, it enhanced interferon-induced protein of 10 kDa secretion, mRNA expression, and promoter activity induced by suboptimal concentrations of interferon-gamma. Interferon-stimulated response element and two nuclear factor-kappaB sites on interferon-induced protein of 10 kDa promoter were responsible for the enhancement by substance P. Substance P alone enhanced transcriptional activity and transcription factor binding through the two nuclear factor-kappaB sites, whereas it did not alter interferon-gamma-induced transcriptional activity and transcription factor binding through interferon-stimulated response element. The effects of substance P on interferon-induced protein of 10 kDa production and nuclear factor-kappaB activation were inhibited by neurokinin-1 receptor antagonist, phospholipase C inhibitor, intracellular Ca2+ chelator, and anti-oxidant. These results suggest that substance P may induce nuclear factor-kappaB activation and interferon-induced protein of 10 kDa production in synergy with interferon-gamma via neurokinin-1 receptor on keratinocytes. These effects of substance P may be mediated via phospholipase C activation, intra-cellular Ca2+ signal, and reactive oxygen intermediates.

Histamine inhibits the production of interferon-induced protein of 10 kDa in human squamous cell carcinoma and melanoma

Interferon-induced protein of (IP-10) inhibits tumor progression. Tumor cells can produce interferon-induced protein of IP-10 in response to interferon-g. Histamine in the vicinity of tumor cells may sustain the tumor progression. We examined the in vitro effects of histamine on interferon-induced protein of IP-10 production in human squamous cell carcinoma and melanoma. Histamine suppressed interferon-g-mediated interferon-induced protein of IP-10 secretion and mRNA expression in SV40-transformed keratinocytes, SCC15, SCC4, and melanoma WM115, WM266-4, and C32. Histamine suppressed interferon-g-induced interferon-mediated protein of IP-10 promoter activation in these cells, and the interferon-stimulated response element on the promoter was responsible for the suppression. Histamine suppressed interferon-g-mediated transcription through the interferon-stimulated response element and signal transducer and activator of transcription 1alpha binding to the interferon-stimulated response element. Histamine suppressed interferon-g-induced tyrosine phosphorylation of the signal transducer and activator of transcription 1alpha, Janus tyrosine kinase 1, and Janus tyrosine kinase 2. Histamine-mediated suppression on the interferon-g-induced interferon-mediated protein of IP-10 synthesis was counteracted by the H2 receptor antagonist cimetidine, adenylate cyclase inhibitor SQ22536, and protein kinase A inhibitor H-89, but were not affected by H1 receptor antagonist mepyramine. Cimetidine, SQ22536, and H-89 also counteracted histamine-mediated suppression on the interferon-g-induced transcription through the interferon-stimulated response element, signal transducer and activator of transcription 1alpha binding to the interferon-stimulated response element, and tyrosine phosphorylation of the signal transducer and activator of transcription 1alpha, Janus tyrosine kinase 1, and Janus tyrosine kinase 2. Histamine increased intracellular 3',5'-adenosine cyclic monophosphate level and protein kinase A activity in squamous cell carcinoma and melanoma, and the effects of histamine were blocked by cimetidine. These results suggest that histamine may interact with H2 receptor on squamous cell carcinoma and melanoma and generate 3',5'-adenosine cyclic monophosphate, which may activate protein kinase A. The cyclic 3',5'-adenosine monophosphate/protein kinase A signaling pathway induced by histamine may inhibit interferon-g-induced signal transducer and activator of transcription 1alpha activation and suppress interferon-induced protein of IP-10 synthesis.

Cyclooxygenase-2 inhibitor enhances whereas prostaglandin E2 inhibits the production of interferon-induced protein of 10 kDa in epidermoid carcinoma A431

Interferon-induced protein of 10 kDa (IP-10) induces antitumor immunity. Cyclooxygenase-2 and its metabolite prostaglandin E2 (PGE2) are overexpressed in tumor cells, which may suppress antitumor immunity. We examined the in vitro effects of cyclooxygenase-2 inhibitor NS398 on IP-10 production in human epidermoid carcinoma A431. NS398 enhanced interferon-gamma-induced IP-10 secretion, mRNA expression, and promoter activation in A431, and exogenous PGE2 antagonized the enhancement. Interferon-stimulated response element (ISRE) on IP-10 promoter was responsible for the transcriptional regulation by NS398 and PGE2. NS398 enhanced interferon-gamma-induced transcription through ISRE and binding of signal transducer and activator of transcription 1alpha (STAT1alpha to ISRE in A431, and PGE2 antagonized the enhancement. NS398 enhanced interferon-gamma-induced tyrosine phosphorylation of STAT1alpha, Janus tyrosine kinase 1, and Janus tyrosine kinase 2, and PGE2 antagonized the enhancement. PGE2-mediated suppression of IP-10 synthesis was counteracted by adenylate cyclase inhibitor SQ22536 and protein kinase A inhibitor H-89, and PGE2 receptor EP4 antagonist AH23848B. AH23848B, SQ22536, and H-89 counteracted the PGE2-mediated suppression of ISRE-dependent transcription, STAT1alpha binding to ISRE, and tyrosine phosphorylation of STAT1alpha, Janus tyrosine kinase 1, and Janus tyrosine kinase 2. PGE2 increased intracellular cAMP level and protein kinase A activity in A431 pretreated with NS398, and AH23848B blocked the effects of PGE2. These results suggest that A431-derived PGE2 may generate cAMP signal via EP4 in A431, which may activate protein kinase A, and may resultantly inhibit interferon-gamma-induced STAT1alpha activation and IP-10 synthesis. The results also suggest that NS398 may restore IP-10 synthesis by preventing PGE2 production in A431 and thus may be therapeutically useful for skin cancer.

Diesel exposure favors Th2 cell recruitment by mononuclear cells and alveolar macrophages from allergic patients by differentially regulating macrophage-derived chemokine and IFN-gamma-induced protein-10 production

Diesel exhausts and their associated organic compounds may be involved in the recent increase in the prevalence of allergic disorders, through their ability to favor a type 2 immune response. Type 2 T cells have been shown to be preferentially recruited by the chemokines eotaxin (CCL11), macrophage-derived chemokine (MDC, CCL22), and thymus activation-regulated chemokine (CCL17) through their interaction with CCR3 and CCR4, respectively, whereas type 1 T cells are mainly recruited by IFN-gamma-induced protein-10 (CXCL10) through CXCR3 binding. The aim of the study was to evaluate the effect of diesel exposure on the expression of chemokines involved in type 1 and 2 T cell recruitment. PBMC and alveolar macrophages from house dust mite allergic patients were incubated with combinations of diesel extracts and Der p 1 allergen, and chemokine production was analyzed. Diesel exposure alone decreased the constitutive IP-10 production, while it further augmented allergen-induced MDC production, resulting in a significantly increased capacity to chemoattract human Th2, but not Th1 clones. Inhibition experiments with anti-type 1 or type 2 cytokine Abs as well as cytokine mRNA kinetic evaluation showed that the chemokine variations were not dependent upon IL-4, IL-13, or IFN-gamma expression. In contrast, inhibition of the B7:CD28 pathway using a CTLA-4-Ig fusion protein completely inhibited diesel-dependent increase of allergen-induced MDC production. This inhibition was mainly dependent upon the CD86 pathway and to a lesser extent upon the CD80 pathway. These results suggest that the exposure to diesel exhausts and allergen may likely amplify a deleterious type 2 immune response via a differential regulation of chemokine production through the CD28 pathway.

Dominant expression of CXCR3 is associated with induced expression of IP-10 at hapten-challenged sites of murine contact hypersensitivity: a possible role for interferon-gamma-producing CD8(+) T cells in IP-10 expression

Murine contact hypersensitivity is elicited as a consequence of immunologic reactions triggered by skin-applied antigen, interactions among Langerhans cells, T cells, keratinocytes and mast cells, and a variety of chemokines generated by cellular interactions. In this study, we sensitized and challenged BALB/c mice with hapten, dinitrofluorobenzene or picryl chloride, and examined the expressions of mRNA for chemokines and their receptors by reverse transcription-polymerase chain reaction in the skin of elicited earlobes. CXC chemokines, IP-10 and Mig, were transcribed 24-48 h after challenge. This was associated with the expression of their agonistic receptor CXCR3, while mRNA for TARC and MDC, and their receptor CCR4 were not detected. Since CXCR3 and CCR4 are expressed preferentially on types 1 (Th1/Tc1) and 2 (Th2) T cells, respectively, the results suggested that the former type of T cells predominantly infiltrate at the elicited sites. Immune lymph node cells of the sensitized mice also expressed mRNA for CXCR3 but not CCR4 with concomitant transcription of interferon-gamma (IFN-gamma) but not interleukin-4 subsequent to challenge. The percentage of lymph node CD8(+) T cells was increased from 16% in naive mice to 30-50% in hapten-challenged mice, and in the immune lymph nodes, CD8(+) cells were the major source of IFN-gamma compared to CD4(+) cells. Since IFN-gamma is known to stimulate keratinocytes to produce IP-10 and Mig, it is suggested that these IFN-gamma-producing CD8(+) T cells enhance the production of these chemokines, thereby functioning as not only the effector cells but also the cytokine source to sustain the challenge reaction.

Cell-density-regulated chemotactic responsiveness of keratinocytes in vitro

Keratinocytes represent the main constituents of the epidermis and have been found to play a regulatory role in a variety of inflammatory skin diseases. The functional activity of keratinocytes is highly heterogeneous, and depends on the cell localization in the epidermal architecture, and the maturation or differentiation state of the cells. Spontaneously proliferating HaCaT cells, showing several similarities to basal epidermal keratinocytes, were found to respond to external chemoattractants, including the chemokines RANTES (regulated on activation normal T cell expressed and secreted) and interleukin-8 and the mu-opioid agonist DAMGO ([d-ala2, N-Me-Phe4, Gly-ol5]enkephalin) in migration assays. The chemotactic responsiveness was highly dependent on the cell density of the monolayer, with greatest chemotactic activity at the highest cell density. Whereas RANTES was found to be the most potent chemoattractant, constitutive RANTES production was also detected in the HaCaT cultures. We found an inverse correlation between constitutive RANTES production and chemotactic responsiveness toward external RANTES, suggesting a possible functional down-modulation of the RANTES receptors, CC chemokine receptor 1 and CC chemokine receptor 5, during culture. Results from confocal laser scanning microscopy showed reduced CC chemokine receptor 1, but not CC chemokine receptor 5, expression by HaCaT cells at low cell densities, which was abolished in the presence of neutralizing antibodies against RANTES. The total CC chemokine receptor 1 pool (surface and intracellular receptors), however, showed no significant change during in vitro culture. Chemotactic responsiveness toward RANTES was directly correlated with the level of CC chemokine receptor 1 surface expression. Taken together these results show that with keratinocyte proliferation and the progressive increase in cell density there are dramatic alterations in keratinocyte function.

Processing of natural and recombinant CXCR3-targeting chemokines and implications for biological activity

Chemokines comprise a class of peptides with chemotactic activity towards leukocytes. The potency of different chemokines for the same receptor often varies as a result of differences in primary structure. In addition, post-translational modifications have been shown to affect the effectiveness of chemokines. Although in several studies, natural CXCR3-targeting chemokines have been isolated, detailed information about the proteins and their possible modifications is lacking. Using a combination of liquid chromatography and mass spectrometry we studied the protein profile of CXCR3-targeting chemokines expressed by interferon-gamma-stimulated human keratinocytes. The biological implications of one of the identified modifications was studied in more detail using calcium mobilization and chemotaxis assays. We found that the primary structure of human CXCL10 is different from the generally accepted sequence. In addition we identified a C-terminally truncated CXCL10, lacking the last four amino acids. Native CXCL11 was primarily found in its intact mature form but we also found a mass corresponding to an N-terminally truncated human CXCL11, lacking the first two amino acids FP, indicating that this chemokine is a substrate for dipeptidylpeptidase IV. Interestingly, this same truncation was found when we expressed human CXCL11 in Drosophila S2 cells. The biological activity of this truncated form of CXCL11 was greatly reduced, both in calcium mobilization (using CXCR3 expressing CHO cells) as well as its chemotactic activity for CXCR3-expressing T-cells. It is concluded that detailed information on chemokines at the protein level is important to characterize the exact profile of these chemotactic peptides as modifications can severely alter their biological activity.

Differential expression of CXCR3 targeting chemokines CXCL10, CXCL9, and CXCL11 in different types of skin inflammation

Recruitment of activated T-cells to the skin is a common feature in a wide variety of inflammatory skin diseases. As CXCR3 activating chemokines CXCL10 (IP-10), CXCL9 (Mig), and CXCL11 (IP-9/I-TAC) specifically attract activated T-cells, this study addressed the question of whether differences in the expression of these chemokines correlate with the site and cellular composition of the skin infiltrates in different types of inflammatory skin disease. Skin biopsies from lichen planus, chronic discoid lupus erythematosus, allergic patch test reactions, psoriasis, and Jessner's lymphocytic infiltration of the skin were investigated for chemokine expression using RNA in situ hybridization, and for the expression of CXCR3 using immunohistochemistry. The results showed differential expression of CXCL10, CXCL9, and CXCL11, which correlated with differences in the localization and cellular composition of the infiltrates. Whereas CXCL10 and CXCL11 were mainly expressed by basal keratinoctyes, CXCL9 mRNA expression was located predominantly in the dermal infiltrates. Correlation with immunohistochemical data suggested that macrophages and activated keratinocytes were the main producers of these chemokines. CXCR3 was expressed by a majority of both CD4+ and CD8+ infiltrating T-cells, suggesting a functional interaction between locally produced chemokines and CXCR3-expressing T-cells. In conclusion, these findings indicate that these CXCR3 activating chemokines play a significant role in the recruitment and maintenance of T-cell infiltrates in the inflammatory skin diseases studied.

The antipsoriatic drug dimethylfumarate strongly suppresses chemokine production in human keratinocytes and peripheral blood mononuclear cells

BACKGROUND

The effectiveness of systemic treatment of psoriasis with fumaric acid esters has been proven, but their mode of action at the cellular and molecular level has not yet been fully elucidated.

OBJECTIVES

To study the effect of dimethylfumarate (DMF) on the production of the chemokines CXCL1, CXCL8, CXCL9, CXCL10 and CXCL11, formerly known as GROalpha, interleukin-8, Mig, IP-10 and IP-9/I-TAC, respectively, in human keratinocytes and peripheral blood mononuclear cells (PBMC).

METHODS

Cultured keratinocytes were stimulated with interferon (IFN) -gamma to produce CXCL9, CXCL10 and CXCL11 and with phorbol myristate acetate to produce CXCL1 and CXCL8 in the absence and presence of DMF (5, 15 and 45 micromol L(-1)). PBMC were stimulated with either IFN-gamma to produce CXCL9 and CXCL10 or lipopolysaccharide to produce CXCL8, in the absence and presence of DMF (5, 15 and 45 micromol L(-1)). RNA preparations from isolated keratinocytes were analysed by Northern blotting; protein production by keratinocytes and PBMC was monitored by an enzyme-linked immunosorbent assay.

RESULTS

Northern blot analysis on isolated keratinocyte RNA preparations showed a dose-dependent inhibition of CXCL1, CXCL8, CXCL9, CXCL10 and CXCL11 transcription by DMF. At 45 micromol L(-1) the inhibition was almost complete. In addition, keratinocytes and PBMC showed in the presence of DMF a dose-dependent inhibition of CXCL8, CXCL9 and CXCL10 protein production.

CONCLUSIONS

These results show the ability of DMF to inhibit the production of chemokines that may be critically involved in the development and perpetuation of psoriatic lesions. This might explain, at least in part, the beneficial effects of treatment with fumaric acid esters in psoriasis patients.

Appearance of peculiar vessels with immunohistological features of high endothelial venules in the dermis of moxibustion-stimulated rat skin

Morphological changes of the dermal blood vessels ofmoxibustion-stimulated rat skin were examined with reference to the lymphocyte migration. After long-term stimulation with direct moxibustion to the acupoint tsu-san-li (St-36), peculiar vessels that possess immunohistological features of high endothelial venules could be observed in the moxa-stimulated acupoint dermis. Endothelial cells of the vessels had well-developed Golgi apparatus in their plump cytoplasms, and they strongly expressed intercellular adhesion molecule-1 on the luminal surface. These data suggest that the appearance of the peculiar vessels in the dermis acts toward the active infiltration of blood-lymphocytes into the acupoint skin.

Up-regulation of macrophage inflammatory protein-3 alpha/CCL20 and CC chemokine receptor 6 in psoriasis

Autoimmunity plays a key role in the immunopathogenesis of psoriasis; however, little is known about the recruitment of pathogenic cells to skin lesions. We report here that the CC chemokine, macrophage inflammatory protein-3 alpha, recently renamed CCL20, and its receptor CCR6 are markedly up-regulated in psoriasis. CCL20-expressing keratinocytes colocalize with skin-infiltrating T cells in lesional psoriatic skin. PBMCs derived from psoriatic patients show significantly increased CCR6 mRNA levels. Moreover, skin-homing CLA+ memory T cells express high levels of surface CCR6. Furthermore, the expression of CCR6 mRNA is 100- to 1000-fold higher on sorted CLA+ memory T cells than other chemokine receptors, including CXCR1, CXCR2, CXCR3, CCR2, CCR3, and CCR5. In vitro, CCL20 attracted skin-homing CLA+ T cells of both normal and psoriatic donors; however, psoriatic lymphocytes responded to lower concentrations of chemokine and showed higher chemotactic responses. Using ELISA as well as real-time quantitative PCR, we show that cultured primary keratinocytes, dermal fibroblasts, and dermal microvascular endothelial and dendritic cells are major sources of CCL20, and that the expression of this chemokine can be induced by proinflammatory mediators such as TNF-alpha/IL-1 beta, CD40 ligand, IFN-gamma, or IL-17. Taken together, these findings strongly suggest that CCL20/CCR6 may play a role in the recruitment of T cells to lesional psoriatic skin.

The CXCR3 activating chemokines IP-10, Mig, and IP-9 are expressed in allergic but not in irritant patch test reactions

Differentiation between allergic and irritant contact dermatitis reactions is difficult, as both inflammatory diseases are clinically, histologically, and immunohistologically very similar. Previous studies in mice revealed that the chemokine IP-10 is exclusively expressed in allergic contact dermatitis reactions. In the present study, we investigated whether the mRNA expression of IP-10 and the related CXCR3 activating chemokines, Mig and IP-9 are also differentially expressed in human allergic contact dermatitis and irritant contact dermatitis reactions. Skin biopsies from allergic (13 cases) and sodium lauryl sulfate-induced irritant patch test reactions (13 cases), obtained 1-72 h after patch testing, were studied by means of an in situ hybridization technique. Results of chemokine mRNA expression were correlated with clinical scoring, histology, and immunohistochemical data including the proportion of inflammatory cells expressing CXCR3, the receptor for IP-10, Mig, and IP-9, and ICAM-1 and HLA-DR expression on keratinocytes. IP-10, Mig, and IP-9 mRNA were detected in seven of nine allergic contact dermatitis reactions after 24-72 h, but not in sodium lauryl sulfate-induced irritant contact dermatitis reactions. ICAM-1 expression by keratinocytes was only found in allergic contact dermatitis reactions and correlated with chemokine expression. Moreover, up to 50% of the infiltrating cells in allergic contact dermatitis expressed CXCR3, in contrast to only 20% in irritant contact dermatitis reactions. In conclusion, we have demonstrated differences in chemokine expression between allergic contact dermatitis and irritant contact dermatitis reactions, which might reflect different regulatory mechanisms operating in these diseases and may be an important clue for differentiation between allergic contact dermatitis and irritant contact dermatitis reactions.

Genomic organization, sequence and transcriptional regulation of the human CXCL 11(1) gene

CXCL 11, encoded by the cDNA sequences designated beta-R1, H-174, or I-TAC, is a CXC chemokine ligand for CXCR3 and assumed to be involved in inflammatory diseases characterized by the presence of activated T-cells. We here describe the genomic organization (four exons interrupted by three introns of 585, 98 and 230 bp) and sequence including 960 bp from the immediate 5'-upstream region of the human CXCL 11 gene. Within the promoter region, consensus sequences for regulatory elements (ISRE, GAS, NF-kappaB) important for cytokine-induced gene transcription were identified. The effect of (pro)inflammatory cytokines on CXCL 11 mRNA expression in monocytic cell lines (THP-1, U937) and primary cultures of dermal fibroblasts and endothelial cells were examined using Northern blot analysis. For these cell types, IFN-gamma was a potent inducer of CXCL 11 transcription, which was synergistically enhanced by TNF-alpha.

IP-10 mRNA expression in cultured keratinocytes is suppressed by inhibition of protein kinase-C and tyrosine kinase and elevation of cAMP

IFN-gamma-inducible protein-10 (IP-10) is a chemokine, which plays an important role in mediating inflammation by attracting activated T cells, and it has been demonstrated in inflammatory skin diseases and cutaneous T cell lymphomas. Keratinocytes can abundantly produce IP-10 mRNA after IFN-gamma treatment. In this study we explored possibilities to downregulate IP-10 expression using human cultured keratinocytes as a model system. Decreased IP-10 mRNA levels were found using specific inhibitors of protein kinase (PK)-C (H-7 and Calphostin C). Moreover, depletion of PK-C by pretreatment of the cells with phorbol myristate (PMA) also down-regulated IP-10 mRNA expression. In addition, elevated cAMP levels were shown to inhibit IP-10 mRNA expression as could be concluded from experiments with forskolin and W-7, substances which, directly or indirectly, raise the intracellular cAMP level. With Genistein, an inhibitor of tyrosine kinase, the IFN-gamma-induced IP-10 mRNA expression was also found to be diminished. These data suggest that inhibitors of the IP-10 mRNA expression in cultured keratinocytes may be potentially of clinical relevance to suppress inflammatory processes in the skin.

Human IP-9: A keratinocyte-derived high affinity CXC-chemokine ligand for the IP-10/Mig receptor (CXCR3)

Chemokines and their receptors play a crucial part in the recruitment of leukocytes into inflammatory sites. The CXC chemokines IP-10 and Mig are selective attractants for activated (memory) T cells, the predominant cell type in skin infiltrates in many inflammatory dermatoses. The selectivity for activated T cells can be explained by the fact that both chemokines exert their effects through a common receptor, CXCR3, which is nearly exclusively expressed on activated T cells. The aim of this study was to identify biologically active CXCR3 ligands produced by keratinocytes. To that end, Chinese hamster ovary cells expressing a cDNA encoding CXCR3 were challenged with proteins obtained from interferon-gamma stimulated keratinocytes and subsequently monitored for effects on second messenger systems. By this approach we were able to isolate IP-10 and Mig, and in addition identified a novel highly potent ligand for the CXCR3 receptor, designated interferon-gamma-inducible protein-9, which proved to be chemotactic for activated T cells expressing CXCR3. Protein sequence and mass spectrometric analysis followed by molecular cloning of the cDNA encoding interferon-gamma-inducible protein-9, revealed that interferon-gamma-inducible protein-9 is a CXC chemokine with a molecular mass of 8303 Da. From a GenBank database query it became clear that interferon-gamma-inducible protein-9 is in fact the protein encoded by the cDNA sequence also known as beta-R1, H174 or I-TAC. In situ hybridization experiments showed that interferon-gamma-inducible protein-9 mRNA is expressed by basal layer keratinocytes in a variety of skin disorders, including allergic contact dermatitis, lichen planus, and mycosis fungoides suggesting a functional role for this chemokine in skin immune responses.