Chemotactic cytokines in the epidermis

Dynamic salivary cytokine profile of recurrent aphthous stomatitis patients in thalidomide maintenance treatment

OBJECTIVE

To dynamically compare the longitudinal (time axis) and transverse (between groups) differences of the salivary cytokines during thalidomide maintenance treatment of recurrent aphthous stomatitis.

METHODS

A randomized, controlled, clinical trial was performed. After the initial prednisone treatment, thalidomide (50 mg/d vs. 25 mg/d) was used as a maintenance drug for 4 or 8 weeks. The salivary IL-4, 5, 6, 10, TNF-α, and IFN-γ were dynamically detected with a cytometric bead array.

RESULTS

Overall, the level of six elevated salivary cytokines after prednisone treatment was significantly downregulated, remained low during thalidomide maintenance, and rebounded at recurrence. The effect of 50 mg/d thalidomide on the salivary cytokines was not superior to 25 mg/d medication. The relapse-free period following drug withdrawal was the longest in the subgroup using 25 mg/d thalidomide for 8 weeks. The order of magnitude of IL-6 was the most obvious, and at week 8, only the level of IL-6 in the group (25 mg/d thalidomide for 8 weeks) continued to decline compared with the other groups.

CONCLUSION

Thalidomide maintenance treatment can effectively sustain low levels of salivary IL-4, 5, 6, 10, TNF-α, and IFN-γ of recurrent aphthous stomatitis patients. IL-6 displayed a good correlation with the disease and is expected to become an index for diagnosis and follow-up.

CLINICAL RELEVANCE

Low-dose long-term thalidomide maintenance treatment was supported for recurrent aphthous stomatitis.

TRIAL REGISTRATION

Trial registration number of ChiCTR-IPR-16009759 at http://www.chictr.org/index.aspx .

Sexy again: the renaissance of neutrophils in psoriasis

Notwithstanding their prominent presence in psoriatic skin, the functional role of neutrophilic granulocytes still remains somewhat enigmatic. Sparked by exciting scientific discoveries regarding neutrophil functions within the last years, the interest in these short-lived cells of the innate immune system has been boosted recently. While it had been known for some time that neutrophils produce and respond to a number of inflammatory mediators, recent research has linked neutrophils with the pathogenic functions of IL-17, possibly in conjunction with the formation of NETs (neutrophil extracellular traps). Antipsoriatic therapies exert their effects, at least in part, through interference with neutrophils. Neutrophils also appear to connect psoriasis with comorbid diseases. However, directly tampering with neutrophil functions is not trivial as evinced by the failure of therapeutic approaches targeting redundantly regulated cellular communication networks. It has also become apparent that neutrophils link important pathogenic functions of the innate and the adaptive immune system and that they are intricately involved in regulatory networks underlying the pathophysiology of psoriasis. In order to advocate intensified research into the role of this interesting cell population, we here highlight some features of neutrophils and put them into perspective with our current view of the pathophysiology of psoriasis.

Thalidomide: mechanisms of action

The classification of thalidomide as an orphan drug with anti-inflammatory actions has led to its off-label use in conditions refractory to other medications. Although the observed clinical effects of thalidomide suggest it to have immunomodulatory capabilities, the mechanism of action is unclear. Here we review both the positive and negative studies of thalidomide at the bench in order to improve our understanding of the possible mechanisms of this drug in treating a variety of diseases at the bedside. Studies on the effects of thalidomide on the innate and adaptive immune system as well as tumorigenesis and angiogenesis are discussed.

Transgenic overexpression of interleukin-8 in mouse liver protects against galactosamine/endotoxin toxicity

BACKGROUND/AIMS

CXC chemokines function as survival factors for several types of cells. In this study, we investigated whether CXC chemokines promote survival of liver cells following an apoptotic stimulus in vivo.

METHODS

Apoptosis was induced in mouse liver by treatment with galactosamine and endotoxin (Gal/ET). The influence of CXC chemokines was investigated by comparing Gal/ET responses in wild-type (WT) mice to those in mice with a transgene encoding the CXC chemokine interleukin-8 (IL-8 TG).

RESULTS

IL-8 TG mice displayed less apoptosis and better survival after Gal/ET treatment than did WT mice (60% fewer TUNEL-positive cells at 6 h; 36% better survival at 24 h). Gal/ET toxicity was also preventable in WT mice by pre-treatment with IL-8. Notably, IL-8 was not protective against hepatic apoptosis due to anti-Fas or concanavalin A. In Gal/ET-treated mice, IL-8 promoted liver cell survival by interfering with the mitochondrial pathway of apoptosis. Survival was not attributable to activation of NF-kappaB or up-regulation of anti-apoptotic proteins, but coincided instead with activation of Akt and phosphorylation of the pro-apoptotic protein Bad.

CONCLUSIONS

IL-8 protects liver cells from Gal/ET-mediated apoptosis by signaling through phosphatidylinositol-3 kinase (PI-3K). This is in keeping with the reported mechanism of chemokine-related survival in other tissues.

Candida albicans-induced inflammatory response in human keratinocytes. Candida albicans-induzierte Entzundungsantwort humaner Keratinozyten

Candida albicans strains 3153a, ATCC 48867, CBS 2730, DSM 70014, and Vir 13 were cultivated and sterile C. albicans filtrates were produced. The interaction of soluble Candida factors of these infiltrates with human HaCaT keratinocytes was assayed in vitro. The following parameters were analyzed: cell proliferation, protein synthesis, nuclear matrix protein (NMP) 41 release, cytokine release (IL-1beta, soluble IL-2 receptor, IL-6, and IL-8), and reactive oxygen species (ROS). Cell counts at 1, 12, and 24 h were significantly lower for C. albicans strains CBS 2730 and VIR 13 (P < 0.05). There was no significant change for the remaining strains. Neither the protein synthesis nor the NMP-41 release was significantly affected. IL-6 and IL-8 were stimulated by C. albicans filtrates to different amounts with higher levels in strains of low virulence. There was no effect on the other cytokines. The production of ROS by HaCaT keratinocytes was suppressed. The induction of an inflammatory keratinocyte response by soluble C. albicans factors may play a role among the host-yeast interactions.

Fibroblasts facilitate re-epithelialization in wounded human skin equivalents

The re-epithelialization of the wound involves the migration of keratinocytes from the edges of the wound. During this process, keratinocyte migration and proliferation will depend on the interaction of keratinocytes with dermal fibroblasts and the extracellular matrix. The present study aimed to investigate (1) the role of fibroblasts in the re-epithelialization process and on the reconstitution of the dermal-epidermal junction (DEJ) and (2) differential protein expression during re-epithelialization. For both purposes, three-dimensional human skin equivalents (HSE) were used. A full-thickness wound in HSE was introduced by freezing with liquid nitrogen and a superficial wound by linear incision with a scalpel. The closure of the wound in the absence or presence of exogenous growth factors was followed by monitoring the rate of re-epithelialization and regeneration of the DEJ. The results obtained in this study demonstrate that fibroblasts facilitate wound closure, but they differentially affected the deposition of various basement membrane components. The deposition of laminin 5 at the DEJ was delayed in superficial wounds as compared to the full-thickness wounds. During freeze injury, some basement membrane (BM) components remain associated with the dermal compartment and probably facilitate the BM reconstitution. The re-epithelialization process in full-thickness but not in superficial wounds was accelerated by the presence of keratinocyte growth factor and especially by epidermal growth factor. In addition, we have examined the deposition of various basement membrane components and the differences in protein expression in a laterally expanding epidermis in uninjured HSE. Laminin 5, type IV and VII collagen deposition was decreased in the laterally expanding epidermis, indicating that the presence of these proteins is not required for keratinocyte migration to occur in vitro. Using two-dimensional polyacrylamide gel electrophoresis, we have identified DJ-1, a protein not earlier reported to be differently expressed during the epithelialization process of the skin.

What is the 'true' function of skin?

Conventional textbook wisdom portrays the skin as an organ that literally enwraps whatever each of us stands for as a more or less functional, individual member of the mammalian species, and has it that the skin primarily establishes, controls and transmits contacts with the external world. In addition, the skin has long been recognized to protect the organism from deleterious environmental impacts (physical, chemical,microbiological), and is well-known as crucial for the maintenance of temperature, electrolyte and fluid balance. Now, ever more studies are being published that show the skin to also operate as a huge and highly active biofactory for the synthesis,processing and/or metabolism of an astounding range of e.g. structural proteins, glycans, lipids and signaling molecules. Increasingly, it becomes appreciated that the skin, furthermore, is an integral component of the immune, nervous and endocrine systems, with numerous lines of cross-talk between these systems established intracutaneously (e.g. Ann NY Acad Sci Vol 885, 1999; Endocrine Rev 21:457-487, 2000; Physiol Rev 80:980-1020, 2001; Exp Dermatol 10: 349-367, 2001). All these emerging cutaneous functions beyond the classical image of the skin as a barrier and sensory organ are immediately relevant for many of the quandaries that clinical dermatology, dermatopathology, and dermatopharmacology are still struggling with to-date, and offer the practising dermatologist attractive new targets for therapeutic intervention. Yet, many of these skin functions are not even mentioned in dermatology textbooks and await systematic therapeutic targeting. Following a suggestion by Enno Christophers, the current 'Controversies' feature brings together an unusually diverse council of biologists and clinicians, who share their thought-provoking views with the readers and allow us to peek into the future of research in cutaneous biology, not the least by reminding us of the -- often ignored -- evolutionary and embryonal origins of our favorite organ. Hopefully, this unique discussion feature will foster an understanding of the 'true' skin functions that is both more comprehensive and more profound than conventional teaching on this topic, and will stimulate more than 'skin-deep' reflections on the full range of skin functions.

General anti-microbial properties of the integument in fleece producing sheep and goats

Based on lectin histochemical methods, this study describes the production and distribution of various terminal sugars in the integument of Merino sheep and Angora goats. Additionally, pH measurements were performed for information about environmental conditions of microbes on the skin surface and in the fleece. The results demonstrated strongly positive reactions for alpha-L-fucose in the stratum corneum of Merino sheep, and in the secretions of the skin glands of Angora goats. Moreover, alpha-D-mannose, beta-D-N-acetylglucosamine, alpha-D-N-acetylgalactosamine, alpha-D-galactose and beta-D-galactose were very distinct in the secretions of the skin glands of both species. The skin products containing saccharide residues are deposited on the skin surface and in the fleece as part of wool grease, and the terminal sugars may be liberated by bacterial and fungal activities. All of these sugars are of specific interest because of their ability of inhibiting the adherence of different bacteria and fungi to the epidermal cells. Thus, free sugars impede attacks of skin micro-inhabitants against the integrity of the epidermal barrier. In contrast to these results, the skin pH-conditions were strongly alkaline, particularly in the fleece of Merino sheep (pH 6-9), so that proliferation of microbes may be promoted. This negative influence can only be countered by high production rates of sugar-containing skin products, which is normally the case based on long and intense activity of hair follicles in fine-wool producing sheep and goats.In conclusion, this study demonstrates that a basic anti-microbial biological system exists on the skin surface and within the hair coat, that operates with free sugars before the immune system is activated.

Elevated leukaemia inhibitory factor (LIF) expression in lesional psoriatic skin: correlation with interleukin (IL)-8 expression

Psoriasis is a disease marked by keratinocyte hyperproliferation, neutrophil and lymphocyte infiltration, and aberrant epidermal and dermal expression of cytokines. Previously, it has been shown that LIF appears to be involved in skin inflammation and can induce the expression of IL-8. We sought to determine whether expression of LIF is abnormal in lesional psoriatic skin and whether this correlates with the expression of IL-8. Using reverse transcription polymerase chain reaction, we measured the expression of LIF and IL-8 mRNA in biopsies from normal individuals, non-lesional psoriatic skin, and lesional psoriatic skin. No difference was seen between the expression of IL-8 and LIF in normal and in non-lesional psoriatic skin. However, LIF expression in lesional skin was increased 160% compared with normal biopsies or non-lesional skin (p < 0.001). Immunostaining of frozen sections showed that the expression of LIF protein was principally suprabasal and, in the majority of sections, concentrated mainly in the stratum corneum of the lesional skin, whereas it was mainly in the stratum spinosum of the normal/non-lesional skin. IL-8 mRNA expression did not differ between the non-lesional and normal skin, but expression in the lesional skin was 17.6-fold greater than in normal skin (p < 0.001), and this expression was correlated with the increased LIF expression (r = 0.67, p < 0.001). Although a significant negative correlation was demonstrated between LIF mRNA expression and the duration of the last outbreak of the disease, no other correlations were found between levels of cytokine expression and a variety of parameters including PASI score. These data suggest a role for keratinocyte LIF in the psoriatic lesion and a link between LIF and IL-8 expression.

Interleukin-8 receptor antagonists in pulmonary diseases

Inflammatory cells are thought to be instrumental in the pathophysiology of pulmonary diseases, and control of their recruitment and activation in the lung would appear to be an attractive strategy for therapeutic intervention. Interleukin-8 and related CXC chemokines are involved in the function of neutrophils and T cells, and have been implicated in several lung diseases. Small-molecule antagonists of the interleukin-8 receptors have been identified, which may help elucidate the role of interleukin-8 and related chemokines in the pathophysiology of lung diseases.

Regulated cutaneous gene delivery: the skin as a bioreactor

Epidermal keratinocytes can secrete polypeptides into the bloodstream, and they can be easily expanded in culture and genetically modified. It is thus possible to use epidermal keratinocytes for the systemic delivery of transgene products. Here we review the development of epidermal secretory systems, from cultured keratinocytes to skin grafts and transgenic mouse models. We also discuss a gene-switch approach for regulated cutaneous gene delivery.

The mechanism of mononuclear cell infiltration in oral lichen planus: the role of cytokines released from keratinocytes

To clarify the pathogenesis of oral lichen planus (OLP), we investigated the roles of keratinocytes (KC) in mononuclear cell infiltration. When peripheral blood mononuclear cells (PBMC) obtained from healthy donors were cultured in the presence of culture supernatants of KC separated from the noninflamed gingivae (Nor-KC) and cheek mucosae of patients with OLP (OLP-KC), the number of migrated PBMC across monolayered human umbilical vein endothelial cells (HUVEC) were increased to about 1.3-fold and 1.5-fold of the control level, respectively, with increases of the expression of CD11a, CD11b, CD18, and CD49d on PBMC and intracellular adhesion molecule-1, vascular cell adhesion molecule-1, and endothelial-leukocyte adhesion molecule-1 on HUVEC. The number of migrated PBMC was reduced to about 60% of the control level by pretreatment of PBMC with anti-CD11a or anti-CD18 MAb and reduced to about 70% by pretreatment of HUVEC with anti-CD54 MAb. The pretreatment of PBMC with genistein, H-7, wortmannin, or exoenzyme C3 decreased the migrated PBMC by about 70 to 90%. In agreement with these results, the culture supernatants of OLP-KC up-regulated tyrosine phosphorylation of 62-kDa, 70-kDa, and 102-kDa proteins, phosphatidylinositol-3 kinase, and protein kinase C activities and activated Rho protein level more so than did those of Nor-KC. Additionally, actin reorganization with the formation of membrane ruffles and lamellipodia was distinctly induced by the culture supernatants of OLP-KC. These results indicate that cytokines generated by KC transduce their signals in PBMC, up-regulating the expression of cell surface adhesion molecules and migration activity with reorganization of actin filaments.

Thalidomide increases human keratinocyte migration and proliferation

Thalidomide is reported to have therapeutic utility in the treatment of pyoderma gangrenosum, Behçet's disease, aphthous ulcers, and skin wounds. We investigated the effect of thalidomide on human keratinocyte proliferation and migration, two early and critical events in the re-epithelialization of skin wounds. Thalidomide at concentrations less than 1 microM did not affect keratinocyte viability. Using a thymidine incorporation assay, we found that thalidomide, at therapeutic concentrations, induced more than a 2. 5-fold increase in the proliferative potential of the cells. Keratinocyte migration was assessed by two independent motility assays: a colloidal gold assay and an in vitro scratch assay. At optimal concentrations, thalidomide increased keratinocyte migration on a collagen matrix more than 2-fold in the colloidal gold assay and more than 3-fold in the scratch assay over control. Although pro-migratory, thalidomide did not alter the level of metalloproteinase-9 secreted into culture medium. Thalidomide did, however, induce a 2-4-fold increase in keratinocyte-derived interleukin-8, a pro-migratory cellular autocrine factor. Human keratinocyte migration and proliferation are essential for re-epithelialization of skin wounds. Interleukin-8 increases human keratinocyte migration and proliferation and is chemotactic for keratinocytes. Therefore, thalidomide may modulate keratinocyte proliferation and motility by a chemokine-dependent pathway.

Systemic replacement therapy from genetically modified epidermal keratinocytes

Epidermal keratinocytes are a potential vehicle for gene transfer and systemic delivery. We review data showing that epidermis-secreted protein does indeed reach the circulation, and we discuss factors that bear upon the issue of how much protein epidermal keratinocytes can deliver to the circulation.

A partial catalog of proteins secreted by epidermal keratinocytes in culture

Proteins secreted by epidermal keratinocytes are known to engage in functions other than those directly associated with barrier formation. We have used a previously published culture model to collect proteins secreted by adult human epidermal keratinocytes. Electrophoresis and microsequencing allowed us to identify 20 proteins. The list of proteins includes those known to be produced by keratinocytes (beta-2 microglobulin, betaIG-H3, calgranulin A, cathepsin B and D, E-cadherin, gelatinase B, gelsolin, interstitial collagenase, laminin B2t, plasminogen activator inhibitor-1, protein 14-3-3epsilon, SCC antigen, stratifin, and translationally controlled tumor protein) as well as those not previously known to be secreted by keratinocytes (epididymis secretory protein, maspin, and anti-neoplastic urinary protein). In addition, two proteins were identified that are not known to be secreted (glutathione-S-transferase and heat shock protein 27/28 kDa). The varied nature of the proteins identified suggests that epidermal keratinocytes have physiologic functions that have yet to be identified.

Chemokine receptor CXCR4 expression in endothelium

The expression of chemokine receptor and viral coreceptor CXCR4 is reported in cultured endothelial cells and in arterial endothelium. A 1.9 kb transcript was cloned from cultured bovine aortic (BAEC) and human umbilical vein endothelial cells (HUVEC). CXCR4 mRNA was expressed at high levels in BAEC and HUVEC but was not expressed by cultured bovine arterial smooth muscle cells (BASM) or human umbilical vein smooth muscle cells (HUVSM). Western blotting with polyclonal antibodies demonstrated an approximate 46KD protein in endothelial cells only. In situ hybridization and immunocytochemistry (anti-CXCR4 monoclonal antibody 12G5) revealed both transcript and protein expression in cultured endothelial cells, and in the endothelium of normal aorta but not in aortic smooth muscle. The ligand for CXCR4, stromal cell derived factor 1 (SDF-1) stimulated mobilization of intracellular calcium at a moderate level (37% of the peak response to thrombin), confirming the expression of functional receptor at the endothelial surface. The involvement of CXCR4 in chemokine signaling, chemoattraction (through SDF-1), and its potential viral coreceptor activity suggest a multifunctional role in vascular homeostasis and pathophysiology.

An immunohistochemical study of oral submucous fibrosis

Oral submucous fibrosis (OSF) is a chronic disease of the oral cavity characterized by inflammation and progressive mucosal fibrosis. These reactions may be the result of either direct stimulation from exogenous antigens like areca alkaloids or by changes in tissue antigenicity that may lead to an autoimmune response. This study investigated the presence and distribution of inflammatory cells and MHC class II antigen expression by epithelial and immunocompetent cells using a three-stage immunoperoxidase method on frozen sections. Thirty OSF tissue specimens and ten normal buccal mucosae were studied and compared. All tissues were investigated using antibodies to T cells (CD3), T helper/inducer cells (CD4), T suppressor/ cytotoxic cells (CD8), B cells (CD20), naive T cells and monocytes (CD45RA), macrophages, Langerhans' cells (CD68) and HLA-DR-positive cells (HLA-DR alpha). The predominant cell populations detected in normal tissues were CD3, CD4 and HLA-DR-positive cells. The distribution of CD4-positive cells was similar to that of CD3-positive cells, which were scattered, often uniformly distributed, both in the epithelium and connective tissue. CD8-positive cells were occasionally seen in the normal epithelium and lamina propria. Few scattered B cells (CD20) and macrophages (CD68) were observed in normal mucosa. Naive T cells (CD45RA) were seen in all normal tissues focally concentrated around the connective tissue papillae, with a similar distribution to that of CD3-positive cells. All normal sections showed HLA-DR-positive cells scattered both in the epithelium and in the lamina propria. Epithelial cells did not show any positive reaction to this antibody and many intraepithelial positive cells showed a dendritic morphology. The cell population detected in OSF showed higher numbers of CD3 and HLA-DR-positive cells compared with those of the normal tissues. The pattern of staining for CD4-positive cells in OSF tissues was similar to that of CD3-positive cells both in the epithelium and connective tissue and was higher than that in normal tissues. A few scattered CD8-positive cells and only occasional CD20- and CD68-positive cells were seen in OSF sections. Few CD45RA-positive cells were found in the epithelium and lamina propria of OSF sections. However, OSF specimens showed high numbers of HLA-DR-positive cells in the basal layer of the epithelium, juxtaepithelium and in the lamina propria in a similar distribution to that of CD3 cells compared with the normal tissues. Most HLA-DR-positive cells in the epithelium showed dendrites directed vertically towards the surface. The increased evidence of CD4 and HLA-DR-positive cells in OSF tissues suggests that most lymphocytes were activated and shows an increased presence of Langerhans' cells. The presence of these immunocompetent cells and high ratio of CD4 to CD8 in OSF tissues suggest an ongoing cellular immune response leading to a possible imbalance of immunoregulation and alteration in local tissue architecture.

Reconstitution of chemokine-induced actin polymerization in undifferentiated human leukemia cells (HL-60) by heterologous expression of interleukin-8 receptors

The chemokines interleukin-8 (IL-8) and GRO alpha bind in neutrophils to the interleukin-8 receptor alpha and beta (IL-8R alpha and beta) triggering reorganization of the actin cytoskeleton and activation of phospholipase C (PLC). Reconstitution of chemokine-induced activation of PLC indicated coupling of IL-8R alpha and beta to pertussis toxin-insensitive G alpha 16-proteins as well as to pertussis toxin-sensitive G alpha i2- or G alpha i3-proteins. To identify the signal transduction mechanisms of chemokine-induced actin response, undifferentiated human leukemia cells (HL-60 cells) constitutively expressing G alpha 16-, G alpha i2- and G alpha i3-proteins were chosen for reconstitution studies. Expression of recombinant receptors after transfection of the cells with the cDNA of IL-8R alpha and beta was confirmed by binding studies with radiolabeled ligands. IL-8R alpha bound IL-8 with high affinity (Kd approximately 1 nM) and GRO alpha with low affinity (Kd approximately 1 microM), whereas IL-8R beta bound both IL-8 and GRO alpha with high affinity (Kd approximately 1nM). Flow cytometric actin measurements indicated that high affinity ligand-receptor interactions in both receptor transfectants displayed inducible responses. Pretreatment of transfectants with pertussis toxin caused ADP-ribosylation of G-proteins and blocked chemokine-induced polymerization, indicating involvement of G alpha i2- or G alpha i3-proteins, but not G alpha 16-proteins in this response.

Interleukin-8 and GRO alpha prime human neutrophils for superoxide anion production and induce up-regulation of N-formyl peptide receptors

Interleukin-8 (IL-8) and GRO alpha are leukocyte-attracting peptides of the chemokine family. To study the priming potential of these chemokines, we measured superoxide anion production and up-regulation of N-formyl peptide receptors in human neutrophils. IL-8 and GRO alpha themselves did not stimulate production of significant amounts of superoxide anions but potentiated N-formyl peptide-induced superoxide anion production in a concentration-dependent manner. Binding measurements by flow cytometry at 37 degrees C with fluorescein-labeled N-formyl peptide revealed enhanced total N-formyl peptide binding after pretreatment of neutrophils with IL-8 and GRO alpha. Binding measurements performed at 4 degrees C indicated that the chemokines stimulated the up-regulation of N-formyl peptide receptors at the cell surface but did not alter their affinity for the ligand. This study indicates that IL-8 and GRO alpha, in addition to their known chemotactic activity, prime neutrophils for superoxide anion production, presumably by up-regulating the number of receptors for strong superoxide-anion-triggering stimuli.

Cytokine production by keratinocytes and mononuclear infiltrates in oral lichen planus

Cytokine generation by tissue-infiltrating mononuclear cells (TIMC) and by keratinocytes (KC) was investigated in material obtained from the oral mucosal tissues of patients with oral lichen planus (OLP). Peripheral blood mononuclear cells (PBMC) and chronically inflamed and noninflamed gingival KC (CIG-KC, NOR-KC, respectively) were used as the controls. Compared to NOR-KC and CIG-KC, KC from OLP patients (OLP-KC) produced much more interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) and granulocyte-macrophage colony-stimulating factor (GM-CSF). The OLP-KC superiority in the production of these cytokines was more prominent when the KC were cultured in the presence of interleukin-1 beta (IL-1 beta), lipopolysaccharide and phorbol myristate acetate. OLP-KC also produced more monocyte-chemotactic factor(s) which were not inactivated by the antibodies against GM-CSF, macrophage colony-stimulating factor and monocyte chemoattractant protein-1. TIMC in OLP tissues (OLP-TIMC) were superior to PBMC in the generation of IL-6 and GM-CSF. OLP-TIMC were stimulated to produce more TNF-alpha by IL-1 beta, IL-6 and GM-CSF, more IL-6 by IL-1 beta and GM-CSF, and more GM-CSF by IL-1 beta and IL-6 than PBMC. When compared to cytokine generation in TIMC from the chronically inflamed gingivae, more interferon-gamma, IL-6 and TNF-alpha were generated by OLP-TIMC. These results indicate that KC play a critical role in OLP, producing cytokines including monocyte-chemotactic factor(s), and that the cytokines produced by TIMC and OLP-KC through autocrine and paracrine processes enhance the local inflammatory response.

Single-step purification of recombinant melanoma growth-stimulating activity by anion-exchange high-performance liquid chromatography

The cytokine melanoma growth-stimulating activity (MGSA) is a growth factor for melanoma cells and a chemotaxin for neutrophils. Known purification procedures of MGSA from human sources or expression systems give a low yield and require multiple chromatography steps. Here, a fast and high-yield method for the purification of recombinant MGSA is described. Approximately 500 micrograms MGSA were recovered from the bacterial lysate of a 10 liter culture within a day. For this purpose, total mRNA of Hs294T melanoma cells was isolated and cDNA of MGSA was obtained by reverse transcription and polymerase chain reaction. The cDNA of MGSA was subcloned into the expression vector pGEX-2T, generating a fusion with the Schistosoma japonicum glutathione S-transferase gene. The fusion protein was expressed in E. coli DH5a and purified from the bacterial lysate using glutathione-sepharose beads. MGSA was cleaved from the complex of fusion protein and glutathione-sepharose beads with thrombin and purified to homogeneity by anion-exchange high-performance liquid chromatography with a Mono-S-column. The bioactivity of the recombinant MGSA was assessed by chemotactic migration and triggered [Ca2+]i-transients in human neutrophils. In addition, [125I]MGSA bound specifically to undifferentiated human leukemia cells HL-60 transfected with the cDNA of the interleukin-8 (IL-8) receptor beta with similar properties as [125I]IL-8. Thus, this described method might be a powerful tool to generate large amounts of cytokines in a short time.

Actin polymerization, calcium-transients, and phospholipid metabolism in human neutrophils after stimulation with interleukin-8 and N-formyl peptide

Signal transduction of interleukin-8 (IL-8) was analyzed in neutrophils, and compared with the well known neutrophil activator N-formyl peptide. Stimulation of human neutrophils with IL-8 induced a rapid polymerization of actin as detected by 7-nitrobenz-2-oxa-1,3-diazol-(NBD)-phallacidin staining of f-actin and reduction of monitored right-angle light scatter. Actin polymerization peaked within 10 seconds after the addition of IL-8 and was short-lived as compared to N-formyl peptide-induced stimulation. Analysis of phospholipids by thin-layer chromatography and analysis of deacylation products of lipid extracts by high-pressure liquid chromatography (HPLC) showed that IL-8 triggered a rapid rise of [32P]phosphatidyl-inositol(3,4,5)trisphosphate (PtdInsP3) followed by a slower increase of [32P]phosphatidylinositol(3,4)bisphosphate (PtdIns-3,4-P2) along with a rapid decrease of [32P]phosphatidylinositol(4,5)bisphosphate (PtdIns-4,5-P2). Changes in polyphosphoinositide metabolism were more moderate and transient than those obtained by N-formyl peptide. Moreover, [32P]phosphatidic acid (PA) production stimulated by IL-8 was minimal and transient as compared to the response activated by N-formyl peptide. Both IL-8 and N-formyl peptide induced Ca++ mobilization from intracellular stores, but IL-8 in contrast to N-formyl peptide failed to trigger the secondary influx of Ca++ from the extracellular medium. In summary, IL-8 and N-formyl peptide stimulated similar and distinct patterns of intracellular activation steps. This study indicates that IL-8 is a potent activator of intracellular events presumably required for chemotaxis, but a relatively weak activator for events associated with superoxide anion generation and proinflammatory activity.

Cytokine system as potential target for antipsoriatic therapy

Cytokines are produced by a variety of cells and have numerous of overlapping activities. There is increasing evidence that cytokines play a crucial role in the pathogenesis of psoriasis and of other dermatologic diseases. This review summarizes current knowledge as to how the altered cytokine network is involved in the accumulation of inflammatory cells in lesional skin, and how the cytokines are involved in epidermal hyperproliferation. The actions of the most important therapeutic compounds, such as corticosteroids, dithranol, cyclosporine, retinoids, vitamin D3 analogues and ultraviolet radiation, on the cytokine system are also discussed. Consideration is given as to how the effects on the production of cytokines and/or cytokine receptors contribute to their therapeutic action.

Cytokine release by peripheral blood mononuclear cells is affected by 8-methoxypsoralen plus UV-A

Psoralen plus UV-A (PUVA) is an effective therapy for psoriasis but also for other inflammatory dermatoses. The precise mechanisms of action, however, are not absolutely clear. Therefore, the effect of PUVA on the release of the proinflammatory cytokines interleukin (IL)-1, IL-6, IL-8 and tumor necrosis factor alpha (TNF alpha) was studied. Peripheral blood mononuclear cells (PBMC) obtained from humans were incubated with 8-methoxypsoralen (8-MOP) and exposed to UV-A (20 kJ/m2). This treatment resulted in a significant reduction of IL-6 and IL-8 amounts in the supernatants. In addition, an inhibition of IL-1 beta and TNF alpha production by lipopolysaccharide (LPS)-stimulated PBMC was observed upon PUVA treatment. Accordingly, northern blot analysis showed decreased levels of mRNA encoding for IL-1 beta, IL-6, IL-8 and TNF alpha in PUVA-treated PBMC. Finally PBMC were obtained from psoriatics undergoing oral photochemotherapy before the beginning and after completion of treatment. The PBMC collected after PUVA spontaneously produced significantly less IL-6 and IL-8 in comparison to the respective samples obtained before therapy. A similar suppression of IL-1 beta and TNF alpha by in vivo PUVA was found in LPS-stimulated PBMC. The present data demonstrate that PUVA both in vitro and in vivo suppresses the production of the proinflammatory cytokines IL-1 beta, IL-6, IL-8 and TNF alpha by PBMC. Because these cytokines are important in the mediation of inflammatory reactions, one may speculate that the inhibitory effects could contribute to the antiinflammatory activity of PUVA.

GRO-alpha mRNA is selectively overexpressed in psoriatic epidermis and is reduced by cyclosporin A in vivo, but not in cultured keratinocytes

Interleukin (IL)-8 and gro peptides are members of the intercrine-alpha family of chemotaxins known to be present in biologically active form in psoriasis lesions. However, the relative contribution of the three different gro genes to the expression of this material is unknown, as is the stimulus for gro overexpression in psoriatic lesions. To address these questions, Northern blot and semiquantitative polymerase chain reaction analysis were performed on RNA extracted from keratome biopsies of normal skin, untreated plaques of psoriasis, or plaques treated for 1 week with low-dose cyclosporin A (CsA). Northern blot analysis revealed a significant correlation between gro and IL-8 mRNA levels in psoriasis lesions from 26 different individuals (r = 0.61, p = 0.0009), and overexpression of gro was markedly reduced by CsA prior to detectable clinical improvement (79.3%, p = 0.01, n = 22). To determine which form(s) of gro were overexpressed in psoriatic lesions, total keratome RNA (1 microgram) was analyzed by semiquantitative reverse transcription-polymerase chain reaction (SQRT-PCR). In five patients known to markedly overexpress gro and IL-8 mRNAs by Northern blotting, gro-alpha was approximately six times more abundant than gro-beta, and 25 times more abundant than gro-gamma. In cultured human keratinocytes, all three forms of gro mRNA were increased by IL-1 alpha or by interferon (IFN)-gamma plus tumor necrosis factor (TNF)-alpha. However, in contrast to the situation in vivo, CsA had no inhibitory effect on cytokine-stimulated gro expression in cultured keratinocytes. Taken together, these results demonstrate that the gro-alpha gene is selectively overexpressed in psoriatic lesions and strongly suggest that overexpression of gro is a keratinocyte response to activated T cells in psoriasis.

Mouse dendritic epidermal T cells exhibit chemotactic migration toward PAM 212 keratinocyte culture supernatants

Dendritic epidermal T cells (DETCs) are Thy-1+, CD45+, CD3+, CD4-, CD8-, and T-cell receptor-V gamma 3/V delta 1+ leukocytes that reside normally in adult mouse skin. We have demonstrated previously that keratinocytes serve as adhesion substrates for DETCs, and that interleukin 7 (IL-7), which is produced by keratinocytes, serves as a growth factor for DETCs. The present study was conducted to address the mechanisms by which DETCs migrate into the epidermis, reasoning that keratinocytes may also be a source of chemotactic activity. Short-term DETC lines were 35S-labeled and tested for migration toward Pam 212 keratinocyte culture supernatants using a modified Boyden chamber method; cell movement from upper chambers toward test samples in lower chambers was traced by counting radioactivity. DETC displayed rapid (within 60 min) and marked (> 50%) migration toward keratinocyte supernatants. The majority of cells that had migrated into keratinocyte supernatants expressed the V gamma 3 T-cell receptor, thus verifying that the migrating cells were DETCs. Addition of keratinocyte supernatants to the upper chambers completely blocked migration, suggesting its chemotactic nature. By contrast, no DETC migration was observed toward 3T3 fibroblast supernatants. Chemotactic activities were 1) produced by Pam 212 cells even in the absence of serum; 2) greater than 12 kD in size; 3) heat and pH labile; 4) trypsin sensitive; and 5) precipitated by 60-100% ammonium sulfate. Several cytokines (e.g., IL-1 alpha and IL-8) failed to mediate DETC migration when added to the lower chambers. Likewise, the same cytokines, when added to the upper chambers, failed to inhibit DETC migration toward Pam 212 supernatants. These results support our hypothesis that keratinocytes facilitate the residence of DETC in epidermis by secreting unique chemotactic factors, by providing adhesion substrates, and by elaborating specific growth factors.

Mode of release of interleukin-8 from proliferating human epidermal keratinocytes in vitro

Keratinocytes have been shown to express interleukin-8 (IL-8) mRNA on stimulation with IL-1 and other substances. This has been assumed to account for the large amount of this neutrophil chemotactic cytokine in psoriasis. We found that, without any added agents, commercially available normal human epidermal keratinocytes proliferating in Keratinocyte Growth Medium (KGM) released a chemotactic peptide extracellularly, which was confirmed to be IL-8. To determine whether most of the IL-8 is secreted extracellularly from proliferating keratinocytes or is mainly stored to be released only on stimulation. We quantified cell-associated and released immunoreactive IL-8 from keratinocytes cultured in KGM for up to 11 days at the peptide level. The keratinocytes proliferated, taking a sigmoid growth curve, to reach a plateau at day 7. We found that the amounts of immunoreactive IL-8 gradually increased in the culture supernatant with cell growth but its prominent release took place only after the cell growth reached a plateau. The cell-associated IL-8 was much smaller in amount than that noted in the supernatant. These results suggest that IL-8 constitutively produced by keratinocytes was mostly released extracellular but that the production by actively proliferating cells seems to be far less than that by non-proliferating cells that probably occurred in an autocrine fashion under the stimulation of keratinocyte-derived cytokines accumulated in the culture medium. Neutrophil chemotactic activity assayed concomitantly showed a consistent increase during the culture period, indicating that, with their growth, the keratinocytes release substances other than IL-8 that exert an influence on neutrophil chemotactic functions.