Production of IL-6 by Keratinocytes

Bioactive Lavandula angustifolia essential oil-loaded nanoemulsion dressing for burn wound healing. In vitro and in vivo studies

The aim of this study was to develop a dressing with bioactive lavender in a new form of nanoemulsion, and to verify its biosafety and effectiveness in burn wound healing. As part of this research, the composition of the bioactive carrier of lavender oil in the form of a nanoemulsion obtained using ultrasound was optimised. The mean particle size of the internal phase and polydispersity were determined using the dynamic light scattering method using a Zestasizer NanoZS by Malvern and using cryo-transmission electron microscopy (TEM). These studies confirmed that the selected formulation had a particle size of approximately 180 nm and remained stable over time. The preparation was also subjected to rheological analysis (viscosity approximately 480 mPa·s) and a pH test (approximately 6). A macroemulsion (ME) with the same qualitative composition was developed as a reference. Nanoformulations and MEs were tested for skin penetration using Raman spectroscopy in an in vitro model. Research has shown that both formulations deliver oil to living layers of the skin. Subsequently, studies were conducted to confirm the effect of lavender oil in emulsion systems on the mitigation of the inflammatory reaction and its pro-regenerative effect on the wound healing process in an in vitro cell culture model. The safe concentration of the oil in the emulsion preparation was also determined based on preliminary in vivo tests of skin sensitisation and irritation as well as an hemocompatibility test of the preparation.

Enhanced Biological Activity of a Novel Preparation of Lavandula angustifolia Essential Oil

Lavandula angustifolia, one of the most popular medicinal plants, is the source of a bioactive essential oil characterized by a wide spectrum of biological activity, e.g., antiseptic, analgesic, and anticancer effects. In dermatology, the oil helps to relieve skin inflammation and exhibit wound healing potential. However, the mechanism of action of the lavender oil depends on its composition, which in turn is dependent on the origin and growing conditions. Our study aimed to compare the composition and proregenerative properties of the commercially-available narrow-leaved lavender oil produced in Provence, France, with the oil obtained from the narrow-leaved lavender cultivated locally in Poland. GC/MS analysis showed that self-manufactured essential oil had lower linalool content than commercial oil (23.2 vs. 40.2%), comparable linalyl acetate content (40.6 vs. 44%), while the proportion of lavandulyl acetate was significantly higher (23.2 vs. 5.5%). To determine the influence of lavender oil on the production of proinflammatory cytokines and proregenerative growth factors, gene expression of the selected signaling molecules by HaCaT cells was investigated using real-time PCR. Results showed a concentration-dependent effect of lavender oils on the production of IL-6, IL-8, and VEGF by the keratinocyte cell line. Finally, the potential of the lavender oil to increase the production of VEGF, the most important angiogenic factor, with the in-house preparation performing significantly better in the in vitro cell models was identified.

Anti-acne vulgaris effect including skin barrier improvement and 5α-reductase inhibition by tellimagrandin I from Carpinus tschonoskii

BACKGROUND

Carpinus tschonoskii (CT) has been previously studied for various activities in the improvement of skin diseases. In the present study, we examined the in vitro anti-acne vulgaris (AV) effect of CT leaves (CTL) and tellimagrandin I (TI), one of the main ellagitannins from CT, including skin barrier improvement and 5α-reductase inhibitory activity.

METHODS

To test the anti-AV activities of CTL and TI, firstly, anti-oxidative and anti-inflammatory activities including DPPH radical scavenging activity, nitric oxide (NO) inhibitory activity, and cytokines [interleukin (IL)-6 and IL-8] were tested. Skin barrier improvement experiments were tested using developing cornified envelope (CE) formation, and filaggrin mRNA expression level was determined by RT-PCR. The 5α-reductase inhibitory activity was determined by measuring the testosterone levels in rat liver microsomes.

RESULTS

CTL and TI showed potent anti-oxidative activity and anti-inflammatory activities. Especially, the cytokine production inhibitory activities of TI were found to be similar to the positive control, epigallocatechin gallate (EGCG). CTL and TI enhanced the CE formation and filaggrin mRNA expression levels and showed potent activities compared to that in the positive control, 1.5 mM Ca²⁺. In additionally, CTL and TI showed 5α-reductase inhibitory activities in a dose-dependent manner.

CONCLUSION

The results showed that CTL and TI inhibit AV endogenous factors such as 5α-reductase and inflammatory cytokines and affect exogenous factors such as developing skin barrier function (CE and filaggrin levels). Therefore, CTL and TI may be plant-derived agent, promising in the treatment of acne vulgaris.

Effects of Derinat on ischemia-reperfusion-induced pressure ulcer mouse model

Sodium salt of deoxyribonucleic acid (DNA), Derinat, isolated from the soft roes of Russian sturgeon, has been utilized as an immunomodulator for the treatment of reactive oxygen species (ROS)-associated diseases in clinics. Here we show that treatment with Derinat has an anti-inflammatory and anti-oxidative effects on cutaneous ischemia-reperfusion (IR) injury in pressure ulcer (PU) model mice. Dorsal skin damage and dermal edema in mild PU model mice were attenuated by treatment with Derinat. Immunohistochemical and biochemical analyses showed that Derinat suppressed IR-induced oxidative damage, i.e. accumulation of 8-hydroxy-2'-deoxyguanosine (8-OHdG), and related inflammatory factors such as cyclooxygenase 2 (COX-2) and IL-6 receptor (IL-6R) in dorsal skin from PU model mice. We also verified that phospholyated/non-phosphorylated ratio of extracellular signal-regulated kinase (Erk) and p38 mitogen-activated protein kinase (MAPK) increased after IR, which were attenuated by Derinat. We then compared the effect of Derinat with that of salmon DNA and other PU therapeutic agents, prostaglandin E1 (PGE1) and basic fibroblast growth factor (bFGF), by using severe PU model mice. The effects of Derinat and salmon-DNA were compatible with those of PGE1 and bFGF. These results suggest that Derinat other fish-derived DNA formulation could be effective enough and become intriguing new therapeutic options.

TNF stimulates IL-6, CXCL8 and VEGF secretion from human keratinocytes via activation of mTOR, inhibited by tetramethoxyluteolin

Psoriasis is an autoimmune skin disease characterized by keratinocyte hyperproliferation and chronic inflammation. The pathogenesis of psoriasis involves proinflammatory cytokines, such as tumor necrosis factor (TNF), but the mechanism of keratinocyte activation is not well understood. Here, we show that TNF (10 or 50 ng/mL) stimulates a significant (P < .0001) gene expression and secretion of proinflammatory IL-6, CXCL8 and VEGF from both cultured human HaCaT and normal epidermal human keratinocytes (NHEKs). This effect occurs via activation of the mammalian target of rapamycin (mTOR) signalling complex as shown by Western blot analysis and phospho-ELISAs. Pretreatment with the novel natural flavonoid tetramethoxyluteolin (10-100 μmol L^-1 ) significantly (P < .0001) inhibits gene expression and secretion (P < .0001) of all 3 mediators in a concentration-dependent manner. Moreover, tetramethoxyluteolin (50 μmol L^-1 ) appears to be a potent inhibitor of the phosphorylated mTOR substrates (pmTOR^Ser2448 , pp70S6K^Thr389 and p4EBP1^Thr37/46 ) as compared to known mTOR inhibitors in keratinocytes. The present findings indicate that TNF stimulates skin inflammation via mTOR signalling. Inhibition by tetramethoxyluteolin may be used in the treatment for psoriasis.

Inhibition of imiquimod-induced psoriasis-like dermatitis in mice by herbal extracts from some Indian medicinal plants

Psoriasis is a chronic autoimmune human skin disorder that is characterized by excessive proliferation of keratinocytes, scaly plaques, severe inflammation and erythema. The pathophysiology of psoriasis involves interplay between epidermal keratinocytes, T lymphocytes, leukocytes and vascular endothelium. Increased leukocyte recruitment and elevated levels of cytokines, growth factors and genetic factors like interleukin (IL)-1β, IL-6, IL-17, IL-22, IL-23, tumour necrosis factor (TNF)-α, interferon (IFN)-γ, transforming growth factor (TGF)-β, toll-like receptor (TLR)-2, signal transducer and activator of transcription (STAT-3), 15-lipoxygenase (LOX)-2, coiled-coil alpha-helical rod protein 1 (CCHCR1), steroidogenic acute regulatory protein (StAR) and vitamin D receptor (VDR) are the most critical factors governing the exacerbation of psoriasis. In the present study, an attempt was made to elucidate the preventive role of herbal extracts of four dermo-protective Ayurvedic plants, Tinospora cordifolia (TC), Curcuma longa (CL), Celastrus paniculatus (CP) and Aloe vera (AV), against psoriasis-like dermatitis. Parkes (P) strain mice were initially induced with psoriasis-like dermatitis using topical application of imiquimod (IMQ, 5 %), followed by subsequent treatment with the herbal extracts to examine their curative effect on the psoriasis-like dermatitis-induced mice. The extracts were orally/topically administered to mice according to their ED/LD50 doses. Phenotypical observations, histological examinations, and semi-quantitative reverse transcription PCR (RT-PCR) analyses of the skin and blood samples of the control, IMQ-treated and herbal extract-treated psoriasis-like dermatitis-induced mice lead to the conclusion that the combination extract from all the plants was instrumental in downregulating the overexpressed cytokines, which was followed by the CL extract. Moreover, lesser yet positive response was evident from CP and TC extracts. The results suggest that these plants can prove to have tremendous preventive potential against the disease and can open the way to new therapeutic strategies for psoriasis treatment.

Artificial extracellular matrices composed of collagen I and high sulfated hyaluronan modulate monocyte to macrophage differentiation under conditions of sterile inflammation

Integration of biomaterials into tissues is often disturbed by unopposed activation of macrophages. Immediately after implantation, monocytes are attracted from peripheral blood to the implantation site where they differentiate into macrophages. Inflammatory signals from the sterile tissue injury around the implanted biomaterial mediate the differentiation of monocytes into inflammatory M1 macrophages (M1) via autocrine and paracrine mechanisms. Suppression of sustained M1 differentiation is thought to be crucial to improve implant healing. Here, we explore whether artificial extracellular matrix (aECM) composed of collagen I and hyaluronan (HA) or sulfated HA-derivatives modulate this monocyte differentiation. We mimicked conditions of sterile tissue injury in vitro using a specific cytokine cocktail containing MCP-1, IL-6 and IFNγ, which induced in monocytes a phenotype similar to M1 macrophages (high expression of CD71, HLA-DR but no CD163 and release of high amounts of pro-inflammatory cytokines IL-1β, IL-6, IL-8, IL-12 and TNFα). In the presence of aECMs containing high sulfated HA this monocyte to M1 differentiation was disturbed. Specifically, pro-inflammatory functions were impaired as shown by reduced secretion of IL-1β, IL-8, IL-12 and TNFα. Instead, release of the immunregulatory cytokine IL-10 and expression of CD163, both markers specific for anti-inflammatory M2 macrophages (M2), were induced. We conclude that aECMs composed of collagen I and high sulfated HA possess immunomodulating capacities and skew monocyte to macrophage differentiation induced by pro-inflammatory signals of sterile injury toward M2 polarization suggesting them as an effective coating for biomaterials to improve their integration.

Polyandric acid A, a clerodane diterpenoid from the Australian medicinal plant Dodonaea polyandra, attenuates pro-inflammatory cytokine secretion in vitro and in vivo

Dodonaea polyandra is a medicinal plant used traditionally by the Kuuku I'yu (Northern Kaanju) indigenous people of Cape York Peninsula, Australia. The most potent of the diterpenoids previously identified from this plant, polyandric acid A (1), has been examined for inhibition of pro-inflammatory cytokine production and other inflammatory mediators using well-established acute and chronic mouse ear edema models and in vitro cellular models. Topical application of 1 significantly inhibited interleukin-1β production in mouse ear tissue in an acute model. In a chronic skin inflammation model, a marked reduction in ear thickness, associated with significant reduction in myeloperoxidase accumulation, was observed. Treatment of primary neonatal human keratinocytes with 1 followed by activation with phorbol ester/ionomycin showed a significant reduction in IL-6 secretion. The present study provides evidence that the anti-inflammatory properties of 1 are due to inhibition of pro-inflammatory cytokines associated with skin inflammation and may be useful in applications for skin inflammatory conditions including psoriasis and dermatitis.

Korean red ginseng powder in the treatment of melasma: an uncontrolled observational study

Exposure to the sun, ultraviolet radiation, and oxidative stress are the chief etiologic factors responsible for melasma. The ingredients of Korean red ginseng powder, which include ginsenoside and phenolic compounds, have antioxidative effects and reduce ultraviolet B-induced pigmentation. This study was designed to evaluate the effectiveness and safety of Korean red ginseng powder in patients with melasma. In 25 female patients, 3 g of Korean red ginseng powder was orally administered for a 24 week period. The level of pigmentation and erythema were determined and clinical improvement was evaluated by the melasma area and severity index (MASI), melasma quality of life scale (MELASQoL), and patient- and investigator-rated global improvement scale. After 24 weeks, the MASI score decreased from 8.8 to 5.6, and MELASQoL showed improvement in 91% of patients (p<0.05). The mean level of pigmentation decreased from 184.3 to 159.7 and erythema levels decreased from 253.6 to 216.4 (p<0.05). Additionally, 74% of the patients showed some improvement in both patient- and investigator-rated global improvement scales at week 24. Korean red ginseng powder was well tolerated by most of the patients. In conclusion, Korean red ginseng powder showed good tolerability and beneficial effects in patients with melasma. The use of Korean red ginseng would be counted as a useful adjunctive therapy for patients with melasma.

Oral administration of glucosylceramide ameliorates inflammatory dry-skin condition in chronic oxazolone-induced irritant contact dermatitis in the mouse ear

BACKGROUND

Irritant contact dermatitis (ICD) is an inflammatory skin disease triggered by exposure to a chemical that is toxic or irritating to the skin. A major characteristic of chronic ICD is an inflammatory dry-skin condition with associated itching. Although glucosylceramide (GlcCer) is known to improve the skin barrier function, its mechanism of action is unknown.

OBJECTIVES

Using a mouse model of oxazolone-induced chronic ICD, this study investigated the effects of oral administration of GlcCer on inflammatory dry skin.

METHODS

Chronic ICD was induced by repeated application of oxazolone in mice. GlcCer was orally administered once daily throughout the elicitation phase. The beneficial efficacy of GlcCer on cutaneous inflammation was evaluated by assessing ear thickness, lymph node weight, histological findings, and mRNA expression of pro-inflammatory cytokines such as IL-1β and IL-6. Additionally, parameters of the itch-associated response, including scratching behavior, water content of the skin, and aquaporin-3 levels in the lesional ear, were measured.

RESULTS

Oral GlcCer administration significantly suppressed mRNA expression of the pro-inflammatory cytokines IL-1β and IL-6. GlcCer also suppressed ear swelling, lymph node weight gains, and infiltration of leukocytes and mast cells in ICD mice. In oxazolone-induced ICD mice, GlcCer significantly inhibited irritant-related scratching behavior and dehydration of the stratum corneum, and decreased aquaporin-3 expression.

CONCLUSIONS

Our results indicate that GlcCer suppressed inflammation not only by inhibiting cytokine production but also by repairing the skin barrier function, suggesting a potential beneficial role for GlcCer in the improvement of chronic ICD.

Serum interleukin-6 levels in response to methotrexate treatment in psoriatic patients

BACKGROUND

Psoriasis is a chronic autoimmune hyperproliferative skin disease. In psoriasis, the cutaneous and systemic overexpression of various proinflammatory cytokines, such as interleukin-6 (IL-6) has been demonstrated. Methotrexate (MTX) has been used in the treatment of psoriasis. The aim of this study is to assess the effect of MTX on serum IL-6 levels and also to find the association between PASI score and IL-6 levels in psoriatic patients during MTX therapy.

METHODS

We recruited 20 control subjects and 22 Psoriasis vulgaris patients for this study. The patients were treated with 7.5mg of methotrexate per week for 12 weeks. Folic acid was given at 5mg once daily except on the day of MTX for 12 weeks. There were 2 dropouts, because of increased liver enzyme levels. Blood samples were collected at three intervals (i.e., Day 0, 6 weeks, 12 weeks) from psoriatic patients and only once from control subjects. PASI score, biochemical and hematological parameters were assessed. Serum IL-6 level was analyzed by using ELISA.

RESULTS

Biochemical and hematological parameters showed no significant changes. Serum IL-6 level and PASI score declined significantly (p<0.001) from Day 0 to 12 weeks of MTX treatment and also showed positive correlation before (r=0.992; p<0.000) and after (r=0.987; p<0.000) treatment with MTX. Out of 4 clinical indices of PASI, only 2 indices namely Infiltration (I) and Desquamation (D) showed positive correlation with IL-6 before and after MTX treatment.

CONCLUSION

The treatment response with MTX in psoriatic patients can be seen both at clinical and molecular levels.

Gene expression changes in melanoma metastases in response to high-dose chemotherapy during isolated limb perfusion

Despite recent advances in melanoma therapy, disseminated melanoma still lacks effective treatment, and recurrence of the tumor frequently occurs, even after high-dose chemotherapy. The mechanisms responsible for this chemoresistance or for the formation of new relapses remain poorly understood. Using a human 'model', in which the isolated limb is perfused with high doses of the chemotherapeutic melphalan (ILP), we identified a five-gene set (ATF3, CYR61, IER5, IL6, and PTGS2) of stress-induced genes that was consistently upregulated after ILP in all in-transit metastatic melanoma samples as well as in three melphalan-treated melanoma cell lines. Early post-ILP relapses retained these elevated expressions, whereas the expression of these genes returned to their original levels in late post-ILP recurrences. In addition, we identified upregulation of these genes in the A375 cell line's side population (SP) and melanospheres, established methods to enrich for candidate cancer stem cells (CSCs), which are considered chemoresistant and tumorigenic, and thus proposed to be responsible for tumor relapse. Our data identify an immediate and short-term upregulation of early stress-responsive genes that are potentially linked to chemoresistance and CSCs.

Involvement of IL-17F via the induction of IL-6 in psoriasis

Recently, the important role of T helper 17 (Th17) cells in psoriasis has been clarified; however, the role of IL-17F produced by Th17 cells is still not fully understood. IL-6 exhibits multiple biologic functions, such as regulation of immunological responses including those in psoriatic reactions. Therefore, we examined the production of IL-6 protein in normal human epidermal keratinocytes (NHEKs) stimulated by IL-17F, TNF-alpha, IL-17A, and IL-17A in combination with TNF-alpha, and PBS control. We then examined the expression of IL-6 mRNA in mouse skin after intradermal injection of IL-17F. Finally, IL-17F expression in skin biopsy specimens from psoriasis patients was examined by immunohistochemistry. The results showed that IL-17F induced production of IL-6 in NHEKs in a time-dependent manner. This could be attenuated by chimeric inhibitor blocking the IL-17 receptor. The amounts of IL-6 stimulated by IL-17F were much higher than those stimulated by TNF-alpha or IL-17A. IL-6 was also significantly upregulated via synergistic stimulation with IL-17A plus TNF-alpha. The expression of IL-6 mRNA 24 h after IL-17F injection in the mouse skin was 3.2-fold higher than that in the control group. Immunohistochemistry of inflammatory cells in the dermis demonstrated a large number of CD4(+) T cells showing IL-17F positivity in psoriatic skin lesions, but few or none in non-lesional psoriatic skin. Our results indicate that IL-17F produced by CD4(+) T cells causes the inflammation in psoriasis partly through induction of IL-6 in keratinocytes.

Effect of matrine on the expression of substance P receptor and inflammatory cytokines production in human skin keratinocytes and fibroblasts

Matrine is a kind of alkaloid found in certain Sophora plants, which has been extensively used in China for the treatment of viral hepatitis, cancer, cardiac diseases and skin diseases (such as atopic dermatitis and eczema). It also has been confirmed that substance P (SP) and its receptor (neurokinin-1 receptor, NK-1R) are involved in the pathogenesis of inflammatory skin disorders. So the present study was designed to investigate the effect of matrine on the expression of NK-1R and cytokines production induced by SP in HaCaT cells (a human epidermal keratinocyte cell line) and dermal fibroblasts. In addition, cell viability was also evaluated. The results showed that matrine inhibited the expression of NK-1R in HaCaT cells and fibroblasts. SP induced the production of interleukin (IL)-1beta, IL-8, interferon (IFN)-gamma, and monocyte chemotactic protein (MCP)-1 in both cell types. Matrine 5-100 microg/mL had little effect on cell viability. It inhibited SP-induced IL-1beta, IL-8 and MCP-1 production in HaCaT cells and fibroblasts, while it increased the production of IFN-gamma in HaCaT cells. Both SP and matrine had no effect on the secretion of IL-6. These findings suggest that matrine may have potential treatment function on SP related cutaneous inflammation by inhibition of the expression of substance P receptor and regulation of the production of inflammatory cytokines.

Neuronal conditions of spinal cord in dermatitis are improved by olopatadine

Intense pruritus and cutaneous reactivity represent cardinal features of eczema. The resulting scratching behaviors alter neuronal conditions of the spinal dorsal horn where the primary sensory afferent fibers transmit cutaneous stimulation and deteriorate eczematous skin lesions. We investigated the effects of olopatadine hydrochloride (olopatadine) on alteration of neuronal conditions of the spinal dorsal horn and eczematous skin lesions induced by contact dermatitis. Eczematous lesions were induced by repeated application of diphenylcyclopropenone (DCP) in BALB/c mice. Olopatadine suppressed scratching behavior caused by repeated application of DCP in mice. Increased expressions of c-Fos and substance P in the spinal dorsal horn following DCP application were improved by olopatadine. Furthermore, olopatadine diminished the number of infiltrating cells and levels of cytokines in eczematous skin lesions resulting from DCP application. Olopatadine improves neurological conditions in the spinal cord and eczematous skin lesions in a murine contact dermatitis model.

Evaluation of Hepatic Interleukin-6 Secretion following Portal Vein Ligation Using a Minimal Surgical Stress Model

BACKGROUND

Animal portal vein ligation (PVL) model requires laparotomy under general anesthesia, which induces systemic inflammatory response, and makes the analysis of early signals for hepatic regeneration difficult. We developed a nonstress PVL model, which performs the ligation after surgical stress is subsided, and evaluated the hepatic IL-6 production at early phase of PVL.

MATERIALS AND METHODS

After laparotomy under general anesthesia, a monofilament suture was placed around the left portal vein and knotted, but not tied, and the two ends were delivered through each flank. Seven days after laparotomy, PVL was created by pulling the two ends of the ligature, tightening the ligature.

RESULTS

Biochemical assays indicated that the surgical stress of laparotomy resolved on day 7. Rate of liver regeneration of the nonligated lobe in this model was similar to that in the conventional PVL model. The serum interleukin-6 concentration rose rapidly (within 3 h) after PVL and remained elevated until 6 h. RT-PCR demonstrated that transcripts of IL-6 gene significantly increased 3 h after ligation in the nonembolized lobes. Furthermore, in situ hybridization for IL-6 mRNA was stained at sinusoidal endothelial cells, especially periportal area.

CONCLUSIONS

Our PVL model minimizing surgical stress was comparable to the stress of clinical portal vein embolization. Using this model, we found an increased expression of IL-6 mRNA in the sinusoidal endothelial cells predominantly at the periportal area.

Cytokine profiles of filarial granulomas in jirds infected with Brugia pahangi

Background

A granulomatous inflammatory response develops in jirds infected subcutaneously or intraperitoneally with filarial nematodes namely Brugia pahangi and B. malayi. Previous studies by light and electron microscopy have shown cellular inflammatory responses in and around these granulomas. Furthermore, the cellular inflammatory responses of granulomas found in the lymphatics and peritoneal cavity appear to be similar. The purpose of this study was to determine the cytokine profiles of granulomas in the peritoneal cavity of B. pahangi-infected jirds and to determine whether the granulomas release any proinflammatory cytokines ex vivo.

Methods

A semiautomated quantitative polymerase chain reaction (Q-PCR) was performed on cDNA prepared from the granulomas of infected jirds to study the species-specific mRNA expression of IL-2, IL-4, IFN-γ, IL-5, and IL-10. Genomic DNA was extracted from the granulomas, and parasite DNA was detected by Q-PCR by amplifying the HhaI repeat sequence. The levels of the inflammation-causing cytokines IL-6 and TNFα that were secreted by the granulomas were measured by cell-based assays.

Results

Florid granulomas showed higher levels of IFN-γ than other cytokines, linking this Th1 cytokine to the granulomatous inflammation that develops in jirds and humans. IL-4 expression was much lower than that of IFN-γ but higher than that of IL-10. A low level of IL-5 mRNA expression was detectable in all granulomas as was the level of IL-2 expression. The levels of the inflammatory cytokines IL-6 and TNFα, secreted by intact granulomas, spontaneously increased by 48 h after culture. Parasite antigen stimulation and subsequent release of IL-6 and TNFα by the granulomas indicated a moderate increase in the levels of these two cytokines. The amplification of the Brugia HhaI repeat DNA and Wolbachia 16S rDNA indicated worm components and bacterial components in the granulomatous tissue.

Conclusion

Granuloma development in filarial infections is a complex process involving cellular reactions responding to parasite/bacteria and their components. The interactions between worm-derived granulomas and their hosts are dynamic and multifaceted. The data collected thus far suggest that the expression profiles of many of the measured cytokines in the lymphoid tissues of Brugia-infected jirds are different from those of the cytokines in granulomas. Moreover, granulomas have the ability to secrete the inflammatory cytokines IL-6 and TNFα.

Topical application of a novel immunomodulatory peptide, RDP58, reduces skin inflammation in the phorbol ester-induced dermatitis model

RDP58 is the first lead compound in a series of immunomodulating decapeptides discovered through activity-based screening and computer-aided, rational design. RDP58 disrupts cellular responses signaled through the Toll-like and tumor necrosis factor (TNF) receptor families and occludes important signal transduction pathways involved in inflammation, inhibiting the production of tumor necrosis factor alpha (TNFalpha), interferon-gamma, interleukin (IL)-2, IL-6, and IL-12. These pro-inflammatory cytokines are thought to be involved in the pathogenesis of several inflammatory and autoimmune diseases, including atopic dermatitis and psoriasis. The goal of this study was to determine the ability of RDP58 to inhibit skin inflammation following exposure to the well-characterized protein kinase C activator and tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). Topical application of RDP58 to the epidermis following TPA treatment resulted in the amelioration of the phorbol ester-induced irritant contact dermatitis. Substantial reductions were observed in skin thickness and tissue weight, neutrophil-mediated myeloperoxidase activity, inflammatory cytokine production, and various histopathological indicators. We also found RDP58 to be effective in reducing the compounding inflammatory damage brought on by chronic TPA exposure, and that it is capable of targeting inflammatory mediators specifically in the keratinocyte. These results demonstrate that topically applied RDP58 is an effective anti-inflammatory treatment in the phorbol ester-induced dermatitis model, and suggest that it may have therapeutic potential in a variety of immune-related cutaneous diseases.

Histamine helps development of eczematous lesions in experimental contact dermatitis in mice

Histamine is released from mast cells in the skin, causing urticaria and itching. However, little is known about the roles of histamine in development of eczematous lesions in contact dermatitis. Effects of histamine on development of eczematous lesions in contact dermatitis were assessed using histamine-deficient mice in which contact dermatitis was developed by repeated application of diphenylcyclopropenone. Development of eczematous lesions in contact dermatitis was suppressed in histamine-deficient mice compared to wild-type mice. H(1) agonist ((6-12-(4-imidazol)ethylamino)-N-(4-trifluoro- methylphenyl)hepatanecarboxamide) promoted development of eczematous lesions in histamine-deficient mice. H(1) receptor antagonist (loratadine) suppressed development of eczematous lesions in wild-type mice, whereas H(2) agonist (dimaprit) and receptor antagonist (cimetidine) were ineffective. These results suggest that histamine facilitates the development of eczematous lesions in a murine model of contact dermatitis via H(1) receptors.

Oral intake of proanthocyanidin-rich extract from grape seeds improves chloasma

Chloasma (melasma), an acquired hypermelanosis, is often recalcitrant to various treatments and an amenable, as well as safe, pigment-reducing modality is needed. We investigated that the reducing effect of proanthocyanidin, a powerful antioxidant, on chloasma in a one-year open design study. Proanthocyanidin-rich grape seed extract (GSE) was orally administered to 12 Japanese woman candidates with chloasma for 6 months between August 2001 and January 2002 and to 11 of these 12 for 5 months between March and July 2002. Clinical observation, L* value (lightening) and melanin index, and size (length and width) measurements of chloasma were performed throughout the study period. The first 6 months of GSE intake improved or slightly improved chloasma in 10 of the 12 women (83%, p < 0.01) and following 5 months of intake improved or slightly improved chloasma in 6 of the 11 candidates (54%, p < 0.01). L* values also increased after GSE intake (57.8 +/- 2.5 at the start vs 59.3 +/- 2.3 at 6 months and 58.7 +/- 2.5 at the end of study). Melanin-index significantly decreased after 6 months of the intake (0.025 +/- 0.005 at the start vs 0.019 +/- 0.004 at 6 months) (p < 0.01), and also decreased at the end of study (0.021 +/- 0.005) (p < 0.05). GSE is effective in reducing the hyperpigmentation of women with chloasma. The beneficial effects of GSE was maximally achieved after 6 months and these was no further improvement after this period. The latter GSE intake for 5 months may prevent chloasma from becoming worse prior to the summer season. GSE is safe and useful for improving chloasma.

Neutralization effects of interleukin-6 (IL-6) antibodies on sulfur mustard (HD)-induced IL-6 secretion on human epidermal keratinocytes

The proinflammatory cytokine human interleukin-6 (hIL-6) plays an important role in the early and late courses of inflammation, trauma, and wound healing caused by sulfur mustard (HD). Previously, we demonstrated that hIL-6 might be involved in the early event of structural changes of the signal transducer glycoprotein, which indirectly initiates the cascade of events, such as skin irritation and blister formation observed in the pathophysiology of HD injury. In this present work, we focus on the neutralization effect of IL-6 antibodies with regard to the modulation of hIL-6 secretion. Levels of secreted cytokine hIL-6 in normal human epidermal keratinocytes (NHEK) stimulated with HD (10(-4)M) and incubated for 24h at 37°C were determined by enzyme immunoassay, protein immunocytologic assay and reverse-transcriptase-polymerase chain reaction (RT-PCR). The ratio of HD-treated NHEK to constitutive non-stimulated NHEK controls (S/C) on the induction of hIL-6 is reported. S/C was four-fold higher than non-stimulated NHEK controls as determined by ELISA. By using a more sensitive immunocytologic assay, Luminex(100)™, the increment was verified. hIL-6 levels in NHEK stimulated with HD were 21±11ng/mL as measured by Luminex(100)™. The messenger RNA expression of the cytokine (hIL-6) gene was analyzed semiquantitatively. RT-PCR demonstrated that HD induced an increase in the transcription of hIL-6 gene. Selective immunosuppression, using IL-6 neutralizing antibodies, led to a reduction of such expression of HD-induced transcription of hIL-6 in human keratinocytes. The neutralization by pre-incubating NHEK with monoclonal anti-IL6 antibodies decreased hIL-6 secretion by 76%±1.8 ((*)P<0.05).

Interleukin-1alpha and interleukin-6 enhance the antibacterial properties of cultured composite keratinocyte grafts

OBJECTIVE

To determine whether the antibacterial properties of cultured composite keratinocyte grafts can be enhanced by cytokines that stimulate the innate immune response.

SUMMARY BACKGROUND DATA

Use of composite grafts of cultured keratinocytes has been limited because of their susceptibility to burn wound microorganisms as a result of their lack of a vasculature and immune cells when transplanted. Moreover, use of topical antimicrobial agents is limited with these composite grafts because of cytotoxic effects. Keratinocytes, like all epithelial cells in the body, maintain a natural defense mechanism called the innate immune system. Some components of this system can be induced by cytokines.

METHODS

The innate immune response of cultured composite keratinocyte grafts treated with various cytokines was assessed indirectly by measuring the levels of mRNA encoding antimicrobial peptides (human beta defensin-1 and -2, LL-37, and antileukoprotease) and antimicrobial proteins (lysozyme, bactericidal/permeability-inducing protein, and phospholipase A2) by reverse transcription-polymerase chain reaction and directly by measuring the ability of keratinocytes to inhibit the growth of added bacteria (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus).

RESULTS

Treatment with interluekin-1alpha increased mRNA levels of antimicrobial peptides in keratinocytes on plastic dishes and in composite grafts. Interleukin-6 increased mRNA levels of antimicrobial proteins in composite grafts only. When added to composite grafts, both cytokines increased antibacterial activity against E. coli, P. aeruginosa, and S. aureus. Moreover, interleukin-1alpha and interleukin-6 did not impair the formation of a differentiated epidermis in vitro or after transplantation of the composite grafts.

CONCLUSIONS

Treatment with interleukin-1alpha or interleukin-6 of cultured composite keratinocyte grafts stimulates the innate immune response of keratinocytes, enhances the antibacterial properties of these grafts, and may better prepare them to combat infections in contaminated burn wounds.

Histamine-induced IL-6 and IL-8 production are differentially modulated by IFN-gamma and IL-4 in human keratinocytes

It is known that large amounts of histamine are stored in mast cells located in the superficial dermis of the skin and can be released upon appropriate stimulation. However, the effects of histamine on keratinocyte function have not been well characterized. We therefore examined the capacity of histamine to modulate the production of interleukin (IL)-6 and IL-8 by keratinocytes. We found that histamine significantly augmented the production of IL-6 and IL-8 in a dose- and time-dependent manner. The enhancing effects of histamine were completely inhibited by a potent H1 receptor (H1R) antagonist, emedastine difumarate. Pyrilamine (a much weaker H1R antagonist) and cimetidine (an H2R antagonist) only partially inhibited the enhancing effects of histamine. The histamine-induced up-regulation of IL-6 and IL-8 production, however, was completely abrogated by a combination of pyrilamine and cimetidine. The IL-6 production was significantly enhanced by interferon (IFN)-gamma. Interestingly, IFN-gamma and IL-4 both significantly augmented the histamine-induced IL-6 production. On the other hand, the production of IL-8 was inhibited by IFN-gamma, and IFN-gamma and IL-4 both completely abrogated the histamine-induced IL-8 production. These results suggest that the histamine-induced IL-6 production and IL-8 production are differentially regulated by IFN-gamma and IL-4. Histamine may be an important modulator of cytokine production in epidermal milieu.

IL-4 regulation of IL-6 production involves Rac/Cdc42- and p38 MAPK-dependent pathways in keratinocytes

The stress-activated pathways leading to activation of p38 MAP kinase (p38 MAPK) and c-jun N-terminal kinases (JNK) have been shown to be activated by pro-inflammatory cytokines, physical and chemical stresses as well as a variety of hematopoietic growth factors. One exception is interleukin (IL)-4, which does not activate this pathway in hematopoietic cell. We report here that in A431, a keratinocytic cell line, IL-4 activates Rac and Cdc42 and their downstream effector p21-activated kinase (PAK). Rac and Cdc42 appear to regulate a protein kinase cascade initiated at the level of PAK and leading to activation of p38 MAPK, since IL-4 stimulates tyrosine phosphorylation of p38 MAPK and increases its catalytic activity. As A431 cells are able to produce IL-6 in response to IL-4 stimulation, we assessed the involvement of p38 MAPK in IL-6 gene expression. A pyrimidazole compound, SB203580, a specific inhibitor of p38 MAPK, inhibits production and gene expression of IL-6. SB203580 reduced significantly the stability of IL-6 mRNA. Here we provide evidence that p38 MAPK is activated in response to IL-4 and is involved in IL-6 synthesis by stabilizing IL-6 mRNA.

The effects of substance P and vasoactive intestinal peptide on interleukin-6 synthesis in cultured human keratinocytes

Interleukin-6 (IL-6) is a cytokine implicated as a key mediator of immune and inflammatory responses in psoriasis. Recent studies have shown that neuropeptides, substance P (SP) and vasoactive intestinal peptide (VIP), can modulate a production of IL-6 from cells, such as monocytes and astrocytes, participating in an immune reaction. The aim of this study was to assess the role of the neuropeptides on cytokine production of keratinocytes in physiologic or pathologic conditions. Cultured human keratinocytes derived from normal foreskin and psoriatic lesions were treated with various concentrations of SP or VIP, in the presence or absence of fetal bovine serum. The secretion of IL-6 by the treated keratinocytes was analyzed by enzyme-linked immunosorbent assay. Although neither SP nor VIP, by itself, was able to induce IL-6 synthesis in cultured human keratinocytes, we have found that SP, not VIP, significantly reduced 5% fetal bovine serum-induced IL-6 production in time- and dose-dependent fashion. This down-regulatory effect of SP was reversed by spantide, a SP antagonist. Lesional psoriatic keratinocytes showed a similar, but weaker, response when compared with normal keratinocytes. These data suggested that SP might modulate IL-6 synthesis of keratinocytes in either physiologic or pathologic conditions such as psoriasis.

Induction of transcription factor AP-2 by inflammatory cytokines in human keratinocytes

Activator protein-2 is an important transcription factor for the activation of a number of genes. Here we report the induction of activator protein-2 in response to inflammatory cytokines such as interleukin-6 in keratinocytes. Immunoblotting and semiquantitative reverse transcriptase-polymerase chain reaction assays using normal human keratinocytes revealed that interleukin-6 caused a time- and concentration-dependent induction of activator protein-2 mRNA and protein. The increase of activator protein-2 mRNA was detected at 30 min after stimulation and that of activator protein-2 protein was at 2 h. Their levels were lower than the control levels at 24 h. The interleukin-6-dependent induction of activator protein-2 mRNA was completely blocked by adding actinomycin D, whereas it was approximately 50% affected by cycloheximide. Co-incubation with neutralizing antibodies against various inflammatory cytokines resulted in inhibition of the interleukin-6-dependent activator protein-2 induction at varying degrees, indicating an involvement of various cytokines in the activator protein-2 induction. The activator protein-2 induction was observed in keratinocytes derived from lesional skins with psoriasis or squamous cell carcinoma, and the high levels of activator protein-2 were histochemically detected in these lesions. Furthermore, a gel mobility shift assay using the nuclear extracts from interleukin-6-treated cells showed that interleukin-6 induced the functional activator protein-2 protein for the gene activation. These findings suggest a possible regulation mechanism of activator protein-2 through a complex cytokine system, which is conceivably the initial reaction leading to skin inflammation, and resultant keratinocyte growth and carcinogenesis.

Effects of interferons on the production of interleukin-6 and interleukin-8 in human keratinocytes

Interferons (IFNs) originally described for antiviral activity have been reported to have pleiotropic effects, including the ability to induce interleukin-6 (IL-6) and IL-8 production in several cell types. IL-6 and IL-8 are proinflammatory cytokines and are known to be produced by a wide variety of cells, including human keratinocytes. In the present study, we sought to examine the effects of IFNs on IL-6 and IL-8 production from human keratinocytes. IFN-gamma (10-50 ng/ml) induced IL-6 and IL-8 production dose dependently, but no induction of IL-6 or IL-8 was observed with either IFN-alpha or IFN-beta. Because cytokines often work in a cascade fashion and keratinocytes are a source of primary cytokines, IL-1 alpha, and tumor necrosis factor-alpha (TNF-alpha), we examined whether combined treatment with IFN-gamma and these primary cytokines, IL-1 alpha and TNF-alpha, had a synergistic effect on the production of IL-6 and IL-8. Combined treatment with IFN-gamma and IL-1 alpha induced 6-fold to 7-fold higher levels of IL-6 than IL-1 alpha alone. Combined treatment with IFN-gamma and TNF-alpha induced 11-fold to 12-fold higher levels of IL-6 than TNF-alpha alone. The same treatment induced 3-fold to 4-fold higher levels of IL-8 in both cases. These results suggest that IFN-gamma is a positive regulator for the production of IL-6 and IL-8 from human keratinocytes and likely has an augmentative effect on skin inflammation.

Human keratinocytes constitutively express IL-4 receptor molecules and respond to IL-4 with an increase in B7/BB1 expression

In certain pathological conditions, such as atopic dermatitis, interleukin-4 (IL-4) can be detected in the skin. As the role of this cytokine in inflammatory skin lesions is not completely clear, we investigated its biological effects on skin keratinocytes. It was found that freshly isolated as well as cultured keratinocytes obtained from normal individuals express mRNA for the IL-4 receptor (IL-4R) and produce IL-4R protein, as determined by flow cytometry. Moreover, IL-4 induced a proliferative response in keratinocytes after 1 day of culture and enhanced B7/BB1 expression in these cells. B7-2 (CD86) mRNA and protein were neither detected on untreated nor IL-4 treated keratinocytes. In contrast to interferon-gamma (IFN-gamma), IL-4 did not induce ICAM-1 (CD54) or HLA-DR-expression. Keratinocytes which had been treated with IL-4 showed an enhanced ability to stimulate allogeneic T-cell proliferation in the presence of staphylococcus enterotoxin B (SEB), (p < 0.01). Neutralizing anti-B7/BB1 monoclonal antibodies did not block this effect. These results indicate that other molecules than B7/BB-1. HLA-DR or ICAM-1 on IL-4-activated keratinocytes may be involved in T-cell stimulation. In conclusion our results suggest that locally produced IL-4, besides modulating keratinocyte membrane molecules, may enable keratinocytes to interact with skin infiltrating lymphocytes.

Interleukin-6 in the injured patient. Marker of injury or mediator of inflammation?

OBJECTIVE

The effects of interleukin (IL)-6 in the injured patient are examined in an attempt to clarify the potential pathophysiologic role of IL-6 in the response to injury.

SUMMARY BACKGROUND DATA

Interleukin-6 is an integral cytokine mediator of the acute phase response to injury and infection. However, prolonged and excessive elevations of circulating IL-6 levels in patients after trauma, burns, and elective surgery have been associated with complications and mortality. The mechanistic role of IL-6 in mediating these effects is unclear.

METHODS

A review of current literature is performed to summarize the origins, mechanisms of action, and biologic effects of IL-6 and to characterize the IL-6 response to injury.

RESULTS

Interleukin-6 is a multifunctional cytokine expressed by a variety of cells after a multitude of stimuli, under complex regulatory control mechanisms. The IL-6 response to injury is uniquely consistent and related to the magnitude of the insult. Moreover, the early postinjury IL-6 response correlates with complications as well as mortality.

CONCLUSIONS

Interleukin-6 appears to play an active role in the postinjury immune response, making it an attractive therapeutic target in attempts to control hyperinflammatory provoked organ injury.

IL-1 alpha and IL-6 production by oral and skin keratinocytes: similarities and differences in response to cytokine treatment in vitro

IL-1 alpha and IL-6 are important pro-inflammatory and immunomodulatory cytokines and their production by oral (OK) and skin keratinocytes (SK) was compared. OK and SK produced IL-1 alpha, but not IL-6, constitutively. TNF alpha stimulation increased IL-1 alpha production by both cell types and exhibited synergy with interferon gamma (IFN gamma), although the latter had no effect by itself. In contrast, both cell types produced IL-6 in response to TNF alpha, IFN gamma or IL-4, and IFN gamma and IL-4 exhibited synergy with TNF alpha. For all cytokines the levels of IL-6 production were greater for OK than SK and OK, but not SK, produced IL-6 in response to IL-1 alpha stimulation. In addition, the IL-6 response to IL-4 stimulation was more rapid for OK than SK. These observations may explain the similarities and differences in wound healing and immuno-inflammatory diseases affecting the skin and oral mucosa.

The expression of cytokines by an established basal cell carcinoma cell line (BCC-1/KMC) compared with cultured normal keratinocytes

A basal cell carcinoma (BCC) cell line (BCC-1/KMC) has recently been successfully established from a patient. The production of interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-6 and IL-8 was assessed in comparison with that of cultured normal keratinocytes. The mRNA expression of these cytokines was measured by a reverse transcriptase-polymerase chain reaction (RT-PCR) method and the protein production by an ELISA. The cultured BCC cells spontaneously secreted more IL-6 and IL-8 but less IL-1 than the keratinocytes after culture for 24 h at 37 degrees C. It is suggested that the increased expression of IL-6 and IL-8 may indicate the transformation of normal keratinocytes to locally aggressive BCC.

Epidermal cytokines in allergic contact dermatitis

The understanding of cutaneous immunology has grown significantly during the past decade, particularly regarding the immune function of keratinocytes. Keratinocytes play a major role in immune and inflammatory reactions, mainly through synthesis and release of cytokines. The cytokine network in the skin is an important contributor to normal homeostasis and to the pathogenesis of cutaneous disease. Although cytokine dysregulation has been implicated in the pathogenesis of many cutaneous diseases, allergic contact dermatitis is one that has been the most extensively studied. The aim of this article is to provide a comprehensive current review of the mechanisms of allergic contact dermatitis with particular emphasis on the role of epidermal cytokines.

Augmented expression of cytokines in mouse epidermal tumor cells and its possible involvement in the induction of hematopoietic alterations

Mice with skin tumors induced either by 7,12-dimethylbenz[a]anthracene complete carcinogenesis or subcutaneous injection of a carcinogenic keratinocyte cell line showed moderate to severe splenomegaly as a result of an increase in splenic granulocyte-macrophage and erythroid (erythroid burst-forming unit) progenitors. To test whether the observed alterations involve the release of soluble factors by the epidermal component of skin tumors, we used an in vitro approach. A series of mouse keratinocyte cell lines resembling progressive stages of skin carcinogenesis and carrying either normal or activated Ha-ras genes were assayed for their ability to produce the factors required for colony growth of hematopoietic-committed progenitors. Only the conditioned media of keratinocytes harboring activated Ha-ras genes were able to support the growth of granulocyte-macrophage colony-forming units. In addition, preincubation of normal bone-marrow cells with conditioned media from the transformed epidermal cell lines stimulated in vitro amplification of the hematopoietic granulocyte-macrophage progenitor compartment. To identify the possible factors responsible for the activities detected in the keratinocyte-conditioned media, we performed northern blot analysis using the cytokine probes granulocyte colony-stimulating factor, macrophage colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, stem cell factor, interleukin-1 alpha, interleukin-3, and tumor necrosis factor-alpha. The cell lines expressed different cytokine mRNA combinations that positively correlated with the colony-stimulating activity detected in the corresponding conditioned medium. These results suggest that transformed epidermal tumor cells in vivo may alter normal hematopoiesis as a consequence of the production of cytokines that act in autocrine or paracrine loops probably related to tumor growth.

Cytokine induction in human epidermal keratinocytes exposed to contact irritants and its relation to chemical-induced inflammation in mouse skin

In response to exogenous stimuli such as phorbol-12-myristate 13-acetate, ultraviolet B radiation, and lipopolysaccharide, human keratinocytes produce soluble mediators that are important in primary contact irritancy including cytokines that are associated with proinflammatory properties (interleukin-1 alpha [IL-1 alpha], tumor necrosis factor alpha), chemotaxis (IL-8), and growth activation (granulocyte/macrophage colony stimulating factor, IL-6, transforming growth factor alpha). We examined qualitative and quantitative changes in selected intracellular and secreted cytokines in human keratinocyte cultures in response to non-sensitizing contact irritants (croton oil, sodium lauryl sulfate, methyl salicylate, ethyl phenylpropiolate), sensitizing irritants (oxazolone, dinitrofluorobenzene), and ulcerative agents (phenol, benzalkonium chloride, chromium trioxide). The chemicals were also applied to mouse skin to assess whether the chemical-specific pattern of inflammation correlated with the in vitro production of keratinocyte-derived cytokines. Although all agents elicited neutrophils to the site of chemical application, time dependent and chemical-specific patterns of inflammation could be detected. Sodium lauryl sulfate, phenol, and croton oil induced increases in IL-8 production at non-cytotoxic concentrations in semi-confluent human keratinocyte cultures. Phenol and croton oil stimulated tumor necrosis factor alpha production, whereas croton oil was the only agent found to induce granulocyte/macrophage colony-stimulating factor production. Croton oil, phenol, benzalkonium chloride, and dinitrofluorobenzene induced the intracellular production of IL-1 alpha without a concomitant release into the medium. The release of cytokines occurred in parallel with a relative increase in cytokine-specific mRNA transcripts. Studies using neutralizing antibodies to tumor necrosis factor alpha and IL-1 alpha demonstrated that IL-8 induction by croton oil and phenol occurred directly rather than through autocrine circuits. These data suggest that a given pattern of cytokine production is chemical-specific and may predict the contribution of keratinocytes to skin inflammation.

Interleukin-13 stimulates interleukin-6 production by human keratinocytes. Similarity with interleukin-4

Interleukin-13 (IL-13) is a recently described human lymphokine which is produced by activated T-cells. Its effect on the production of IL-6 by normal keratinocytes and keratinocyte cell lines of human origin was studied and compared to that of IL-4. IL-13, similarly to IL-4, stimulated IL-6 expression by these cells in a dose- and time-dependent manner. Contamination with endotoxin was excluded by the use of polymyxin B and heat-inactivated cytokines. Further, we showed that IL-13, like IL-4, not only stimulated IL-6 production but also was able to induce overexpression of this cytokine in response to an inflammatory signal such as lipopolysaccharide (LPS). In a previous study, we demonstrated that IL-13, by inhibiting IL-6 and other cytokines produced by monocytes, exhibited an 'anti-inflammatory profile' comparable to that displayed by IL-4. In contrast, we show here that IL-13, by stimulating IL-6 production by keratinocytes, may favour the installation of an inflammatory process at a local level and, here again, it acted like IL-4. Therefore, according to the type of target cell these two 'TH2 type' cytokines induce similar opposing effects on IL-6 production and are likely to be important cytokines in the regulation of inflammation at both systemic and local levels.

Differential modulation of interleukin-1 alpha (IL-1 alpha) and interleukin-1 beta (IL-1 beta) in human epidermal keratinocytes by UVB

Conflicting reports exist concerning ultraviolet-B (UVB) effects on keratinocyte (KC) interleukin-1 (IL-1) expression. To clarify the modulatory effects of UVB on IL-1, the following study was undertaken. Normal human epidermal KCs cultured in a standard low Ca2+ and serum-free medium were irradiated in quiescent phase with UVB. In this study, we used semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) to determine the mRNA level of interleukin-1 alpha (IL-1 alpha) and interleukin-1 beta (IL-1 beta). After exposure to 100 or 300 J/m2 UVB, a transient increase in mRNA levels was observed within 1 hour for IL-1 alpha and 3 to 6 h for IL-1 beta. Following this transient induction, mRNA levels for both IL-1 alpha and IL-1 beta returned to steady-state levels after 100 J/m2. After 300 J/m2 irradiation, IL-1 alpha and IL-1 beta levels were downregulated compared to unirradiated cultures at 24-h post-irradiation. The half-life for IL-1 alpha and IL-1 beta was estimated using actinomycin D treatment. Both IL-1 alpha and IL-1 beta mRNAs half-lives (t1/2) decreased faster in irradiated cells (t1/2 = 30 minutes for IL-1 alpha and 2 h for IL-1 beta) compared to unirradiated cells (t1/2 = 1 h and 4 h, respectively). These results suggest that IL-1 alpha and IL-1 beta mRNA expression are differentially regulated by UVB. In contrast to down-regulation of mRNA levels, a significant increase in IL-1 alpha protein levels, measured by ELISA, was observed in culture supernatants from 6 h to 24 h after 300 J/m2 UVB irradiation. Cycloheximide treatment did not abrogate this increase in IL-1 alpha protein level. Since this dose of UVB irradiation decreased the stability of IL-1 alpha and IL-1 beta mRNA, this suggests that the release of IL-1 alpha after UVB irradiation was due to leakage from UVB-damaged cells and not from de novo protein synthesis.

Susceptibility of renal tubular cells to lymphokine-activated killer (LAK) cells: application of culture system using a collagen gel matrix

Monolayer cultures of renal tubular (hKEC) cells were established. These cells formed empty spheroids after 2-3 weeks of culture in a collagen gel matrix. A subcellular polarity from the apex to basement was induced in these "spheroidal" hKEC cells. The weak expression of laminin at the outer surface was evident on spheroidal but not on monolayered hKEC cells. The regulation of HLA-ABC, DR, and intercellular adhesion molecule-1 (ICAM-1) antigens on hKEC cells in the gel matrix was investigated utilizing digestion of gel matrix by collagenase. Enzymatic digestion of the collagen gel did not significantly affect the surface expression of HLA-ABC and ICAM-1, but reduced HLA-DR expression as shown by flow cytometry. The MHC and ICAM-1 molecules on both spheroid-forming and monolayered hKEC cells were upregulated by adding a supernatant of mixed lymphocyte reaction (MLR) and recombinant human interferon (IFN)-gamma. HLA-DR antigen expression was inconsistently induced on the hKEC cells cultured in collagen gel without MLR supernatant or IFN-gamma. In contrast, no HLA-DR expression was found on monolayered hKEC cells in the absence of MLR supernatant or IFN-gamma. Spheroid-forming hKEC cells, when dispersed by enzymatic digestion, were more susceptible to cytolysis by lymphokine-activated killer (LAK) cells than were the enzymatically dispersed, monolayered cells in the 51Cr-release assay. The LAK cells were seen to migrate into the collagen gel and kill the hKEC cells. Thus, LAK cells may function to favor the acceleration of graft rejection.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin-6 levels in amniotic fluid in normal and abnormal pregnancies: preeclampsia, small-for-gestational-age fetus, and premature labor

OBJECTIVE

Our purpose was to determine if abnormal amniotic fluid interleukin-6 levels correlate with pregnancies complicated by preeclampsia, small-for-gestational-age fetus, and premature labor.

STUDY DESIGN

A case control study design was used to compare third-trimester amniotic fluid interleukin-6 levels from women with normal pregnancies (n = 25) and pregnancies complicated by preeclampsia (n = 15), small-for-gestational-age perinates (n = 8), and premature labor (n = 29).

RESULTS

Amniotic fluid interleukin-6 levels in women with preeclampsia and small-for-gestational-age perinates were less than in controls (p < 0.01). Interleukin-6 levels in women with preterm labor refractory to tocolysis were higher than those in women with preterm labor responsive to tocolysis (p < 0.01).

CONCLUSIONS

Interleukin-6 is normally present in amniotic fluid. In the third trimester of pregnancy low levels correlate with small-for-gestational-age fetuses and preeclampsia, whereas elevated levels correlate with preterm labor and delivery.

IL-8 gene expression and production in human keratinocytes and their modulation by UVB

Interleukin (IL)-8 is a member of the supergene family of proinflammatory and chemotactic cytokines recently termed chemokines. IL-8 has been implicated in the pathogenesis of inflammatory skin diseases such as psoriasis. In this study, IL-8 mRNA expression and protein production were determined in normal cultured human epidermal keratinocytes after ultraviolet-B (UVB) irradiation. Messenger RNA levels were determined by the reverse transcriptase-polymerase chain reaction (RT-PCR) method. Total RNA was extracted from cultured keratinocytes at various time points post-irradiation, reverse transcribed to cDNA, and amplified by PCR using a labeled specific primer for the target gene. Amplified products were sized by electrophoresis, visualized by autoradiography, and quantitated by densitometry. Autoradiographs were normalized relative to glyceraldehyde-3-phosphate-dehydrogenase (G3PDH) signals. Constitutive expression of IL-8 mRNA was seen in normal cultured keratinocytes. After 100 or 300 J/m2 UVB irradiation, a rapid increase in IL-8 mRNA level was observed within 1 h after irradiation. At 24 h after irradiation, the mRNA level was elevated 11-13 times compared with the control level. Production of IL-8 protein in culture supernatants was assayed by enzyme-linked immunosorbent assay (ELISA). Significant levels of IL-8 protein were observed at 24 h after irradiation. Cycloheximide treatment blocked this IL-8 protein induction. As IL-8 is known to be an inflammatory cell chemotactic factor, these results suggest a possible role for IL-8 in UVB-induced skin inflammation and diseases.

Increased interleukin 6, but reduced interleukin 1, in delayed pressure urticaria

Interleukin 1 (IL-1) and interleukin 6 (IL-6) were measured by bioassays in suction-blister exudates from lesional skin, from skin immediately following a pressure challenge, and from control skin (not subjected to pressure) of patients with delayed pressure urticaria. IL-6 activity in lesional exudates was significantly higher than in exudates from the other two sites. IL-1 activity in lesional exudates was not significantly higher than in the control exudates, but significantly less IL-1 activity was found immediately after pressure challenge than from the control site.

Modulation of interleukin-1 alpha mRNA expression in mouse epidermis by tumor promoters and antagonists

Increased expression of interleukin-1 (IL-1) in skin elicits a variety of responses, including inflammation and epidermal hyperplasia, which are also characteristic events elicited by tumor promoters. The goal of this study was to investigate whether various classes of tumor promoters increase expression of IL-1 alpha and whether phorbol ester-induced IL-1 alpha expression can be blocked by antitumor promoters. Northern analysis of mRNA isolated from the dorsal skins of SENCAR mice treated with 1 microgram of 4 beta-12-O-tetradecanoylphorbol-13-acetate (TPA) showed that a single application of TPA produced a significant increase in IL-1 alpha mRNA at 6 h that decreased by 24 h after treatment. Two treatments of TPA at 48-h intervals induced, at 6 h, twice as much IL-1 alpha mRNA as one treatment. Of the other promoters tested, anthralin (22.6 micrograms), mezerein (2 micrograms), calcium ionophore A23187 (120 micrograms), and benzoyl peroxide (20 mg) induced IL-1 alpha mRNA with different kinetics and to different extents. On the other hand, the non-tumor promoting phorbol ester analogue 4 alpha-12-O-tetradecanoylphorbol-13-acetate had little effect on the expression of IL-1 alpha mRNA. The effects of various antitumor promoters on TPA-induced IL-1 alpha mRNA expression were also assessed. Fluocinolone acetonide, mepacrine, and 5,8,11,14-eicosatetraynoic acid were the most effective inhibitors, and each produced about 80% inhibition. Other antitumor promoters such as retinoic acid, N-tosyl-L-phenylalanine chloromethyl ketone, and butylated hydroxytoluene inhibited approximately 35%, 65%, and 50% of TPA-induced IL-1 alpha mRNA expression, respectively. Therefore, this study suggests a possible role of IL-1 alpha in the promotion stage of skin carcinogenesis.

Interleukin-6 in psoriasis: expression and mitogenicity studies

Interleukin-6 (IL-6) is a multifunctional cytokine which has been suggested to function as an autocrine mitogen in psoriatic epidermis. We report here the results of several experiments designed to further examine this hypothesis. Blot hybridization was unable to detect 1.3 kb IL-6 transcripts in RNA extracted from normal or psoriatic epidermal (keratome) biopsies, suggesting that IL-6 expression is very low in normal and psoriatic epidermis. Therefore, qualitative and semiquantitative PCR/Southern blot analyses were performed on keratome-derived RNA, and revealed variable but significantly increased IL-6 mRNA levels in lesional psoriatic relative to normal tissue. To further examine the ability of normal human keratinocytes (NHK) to express IL-6, RNA was extracted from rapidly proliferating secondary NHK cultures. IL-6 transcripts were nearly undetectable by blotting in keratinocytes grown in low-calcium serum-free medium, but low levels could be induced by treatment with 1.8 mM CaCl2. IL-6 transcripts were strongly superinduced after cycloheximide treatment, suggesting that a labile protein regulates IL-6 mRNA levels in these cells. Finally, the mitogenic activity of IL-6 was examined in NHK under varying conditions of cell density and added growth factors. IL-6 did not stimulate high density keratinocyte growth in the presence or absence of other growth factors, but did stimulate clonal growth in epidermal growth factor (EGF)-deficient media at high concentrations (> or = 10 ng/ml). The proliferative effects of IL-6, but not of basic fibroblast growth factor, were abrogated by monoclonal antibodies directed against the EGF receptor.(ABSTRACT TRUNCATED AT 250 WORDS)