Inhibition of T helper 2 chemokine production by narrowband ultraviolet B in cultured keratinocytes

A Systematic Review of Keratinocyte Secretions: A Regenerative Perspective

Cell regenerative therapy is a modern solution for difficult-to-heal wounds. Keratinocytes, the most common cell type in the skin, are difficult to obtain without the creation of another wound. Stem cell differentiation towards keratinocytes is a challenging process, and it is difficult to reproduce in chemically defined media. Nevertheless, a co-culture of keratinocytes with stem cells usually achieves efficient differentiation. This systematic review aims to identify the secretions of normal human keratinocytes reported in the literature and correlate them with the differentiation process. An online search revealed 338 references, of which 100 met the selection criteria. A total of 80 different keratinocyte secretions were reported, which can be grouped mainly into cytokines, growth factors, and antimicrobial peptides. The growth-factor group mostly affects stem cell differentiation into keratinocytes, especially epidermal growth factor and members of the transforming growth factor family. Nevertheless, the reported secretions reflected the nature of the involved studies, as most of them focused on keratinocyte interaction with inflammation. This review highlights the secretory function of keratinocytes, as well as the need for intense investigation to characterize these secretions and evaluate their regenerative capacities.

Effects of phenylethanol glycosides from Orobanche cernua Loefling on UVB-Induced skin photodamage: a comparative study

Previous study has found that Orobanche cernua Loefling(OC) and its main ingredient, acteoside, possess excellently anti-photo-aging effect. In addition to acteoside, crenatoside, isoacteoside and 2'-acetylacteoside were also identified as the main phenylethanol glycosides (PhGs) in OC. To screen optimum effective substance and further clarify the photoprotective ingredients of OC, the effects of four major PhGs in OC were compared using UVB-irradiated HaCaT cells. Results indicated that acteoside, isoacteoside and 2'-acetylacteoside effectively decreased UVB-induced MMP-1 expression and stimulated type I procollagen synthesis through inhibition of MAPK/AP-1 and activation of TGF-β/Smad pathway. Moreover, acteoside and 2'-acetylacteoside significantly reduced UVB-induced ROS and TARC secretion, which is involved in the inhibition of NF-κβ/Iκβα and stimulation of Nrf2 antioxidant defense system. However, crenatoside did not show any effect on the regulation of signal cascades mentioned above. Together, our results suggested that 2'-acetylacteoside and isoacteoside also served as efficient agents against UV radiation-induced skin damage. Among them, acteoside and 2'-acetylacteoside showed a higher efficiency than that of isoacteoside, which possessed great potential in treating skin photo-damage.

Review of narrowband ultraviolet B radiation in vitiligo

Vitiligo is a common, acquired pigmentary disorder of unknown etiology with great impact on patient’s appearance and quality of life. It presents a therapeutic challenge to many dermatologists. Photochemotherapy using psoralen and ultraviolet A (UVA) therapy, topical and oral immunosuppresants, as well as cosmetic camouflage are also commonly employed with varying clinical efficacy. Phototherapy is a popular treatment option, which includes both of the generalized ultraviolet B (UVB) therapies, broadband UVB and narrowband UVB (NB-UVB). It has been used favorably, both alone as well as in combination with other agents like topical calcineurin inhibitors, vitamin-D analogs. Combination therapies are useful and may provide quicker regimentation and treat vitiligo with an additive mechanism of action than UVB phototherapy. Advances in technology may lead to the continuing use of UVB phototherapy as a treatment for vitiligo through the development of sophisticated devices and delivery systems as well as innovative application methods. These will provide increased therapeutic options for all vitiligo patients, particularly those with refractory disease. In this article, I have reviewed the available data pertaining to efficacy and safety issues for NB-UVB as monotherapy, its comparison with psoralen plus UVA and other modes of phototherapy, combination regimens that have been tried and future prospects of NB-UVB in vitiligo.

Medium-dose ultraviolet A1 phototherapy and mRNA expression of TSLP, TARC, IL-5, and IL-13 in acute skin lesions in atopic dermatitis

BACKGROUND

The mechanisms responsible for the efficacy of ultraviolet A1 (UVA1) in the treatment of atopic dermatitis (AD) are not fully understood.

OBJECTIVES

This study was designed to investigate mRNA expression of thymic stromal lymphopoietin (TSLP), thymus- and activation-regulated chemokine (TARC), interleukin-5 (IL-5), and IL-13 in AD before and after UVA1 therapy, to determine correlations among them, and to examine whether UVA1 influences their expression and whether it is associated with UVA1 efficacy.

METHODS

Twenty-five patients with AD underwent medium-dose UVA1 phototherapy. Before and after UVA1, biopsies from acute skin lesions were studied using reverse transcription and real-time polymerase chain reaction.

RESULTS

Levels of mRNA TSLP correlated with those of TARC, IL-5, and IL-13, and levels of TARC correlated with those of IL-5 and IL-13, both before and after UVA1. Expression of IL-5 correlated with that of IL-13 only before UVA1. SCORAD (SCORing of Atopic Dermatitis) indices correlated with levels of TARC and IL-5 before irradiation. After UVA1, no mRNA level correlated with the SCORAD index. Phototherapy with UVA1 improved SCORAD values (P < 0.001) and increased expression of TARC (P < 0.05) but did not affect mRNA expression of TSLP, IL-5, or IL-13.

CONCLUSIONS

Expression levels of the mediators TSLP, TARC, IL-5, and IL-13 in AD are interrelated. Phototherapy with UVA1 improves SCORAD indices and increases expression of TARC but has no direct effects on the expression of other molecules. It is likely that UVA1 also interferes with or acts via intermediators on the link between IL-5 and IL-13.

Quantitative analysis and anti-inflammatory effects of Gleditsia sinensis thorns in RAW 264.7 macrophages and HaCaT keratinocytes

Gleditsia sinensis thorns have traditionally been used to treat edema and carbuncles and drain abscesses. In the present study, a simultaneous analysis of four flavonoids [(+)‑catechin, (‑)‑epicatechin, eriodictyol and quercetin] and two phenolic compounds (caffeic acid and ethyl gallate), obtained from a 70% ethanol extract of G. sinensis, was performed using high‑performance liquid chromatography‑photodiode array techniques. In addition, the inhibitory activities of the solvent fractions from a G. sinensis extract and its major constituents on the lipopolysaccharide‑stimulated production of inflammatory mediators by macrophage RAW 264.7 cells and the tumor necrosis factor (TNF)‑α and interferon (IFN)‑γ (TI)‑stimulated production of chemokines by HaCaT keratinocyte cells were investigated. The established analytical method showed high linearity, with a correlation coefficient of ≥0.9998. The limits of detection and quantification of the six compounds were 0.037‑0.425 and 0.124‑1.418 µg/ml, respectively. The ethyl acetate fraction inhibited nitric oxide and prostaglandin E2 production in RAW 264.7 cells and the production of thymus‑ and activation‑regulated chemokine (TARC) in HaCaT cells more than did the other fractions. Furthermore, the six compounds reduced the production of TARC, macrophage‑derived chemokine and regulated on activation normal T‑cell expressed and secreted in TI‑stimulated HaCaT cells; in particular, ethyl gallate and quercetin exhibited a significant dose‑dependent inhibition. Further elucidation of the signaling pathways involved in the T‑helper cell 2 chemokine inhibition by G. sinensis is necessary to facilitate the design of therapeutic agents for the inflammatory response.

Over-expression of tumor necrosis factor-α in vitiligo lesions after narrow-band UVB therapy: an immunohistochemical study

There is a growing evidence that cytokines are important in the depigmentation process of vitiligo, however, the exact mechanism is not fully understood. The aim of this work was to study the possible role of the tumor necrosis factor-α (TNF-α) cytokine in the depigmentation process of the disease. Twenty patients with generalized vitiligo were exposed to narrow-band ultraviolet B (NB-UVB) therapy thrice weekly for a total of 60 sessions. Immunohistochemical examination was done, to assess the TNF-α expression in lesional and perilesional skin as compared to normal control skin, before and after therapy. At baseline, positive lesional TNF-α expression was detected in 60 % of patients which was significantly higher as compared to perilesional skin (20 %) and negative expression in healthy control skin. Post-treatment, a statistically significant increase in TNF-α expression was detected in both lesional (90 %) and perilesional skin (70 %) as compared to baseline (P < 0.05). The significant increase of TNF-α in vitiligo lesions compared with perilesional and healthy skin suggests a possible involvement of this cytokine in the depigmentation of vitiligo. The increase in TNF-α expression after NB-UVB phototherapy suggests another role in repigmentation.

Psidium guajava extract inhibits thymus and activation-regulated chemokine (TARC/CCL17) production in human keratinocytes by inducing heme oxygenase-1 and blocking NF-κB and STAT1 activation

Psidium guajava (P. guajava) is a food and medicinal plant with antioxidant, anti-inflammatory, and anti-allergic activities that support its traditional uses. The aim of this study was to determine the effects of P. guajava ethyl acetate extract (PGEA) on atopic dermatitis and to investigate the possible mechanisms by which PGEA inhibits cytokine-induced Th2 chemokine expression in HaCaT human keratinocyte cells. We found that PGEA suppressed the IFN-γ/TNF-α-co-induced production of thymus and activation-regulated chemokine (TARC) protein and mRNA in HaCaT cells. Additionally, PGEA inhibited the TNF-α/IFN-γ-co-induced activation of NF-κB and STAT1 and increased the expression of heme oxygenase-1 (HO-1) protein and mRNA. HO-1 inhibitor enhanced the suppressive effects of PGEA on TNF-α/IFN-γ-co-induced TARC production and gene expression. Collectively, these data demonstrate that PGEA inhibits chemokine expression in keratinocytes by inducing HO-1 expression and it suggests a possible therapeutic application in atopic dermatitis and other inflammatory skin diseases.

Early detection of tumor cells by innate immune cells leads to T(reg) recruitment through CCL22 production by tumor cells

In breast carcinomas, patient survival seems to be negatively affected by the recruitment of regulatory T cells (T(reg)) within lymphoid aggregates by CCL22. However, the mechanisms underpinning this process, which may be of broader significance in solid tumors, have yet to be described. In this study, we determined how CCL22 production is controlled in tumor cells. In human breast carcinoma cell lines, CCL22 was secreted at low basal levels that were strongly increased in response to inflammatory signals [TNF-α, IFN-γ, and interleukin (IL)-1β], contrasting with CCL17. Primary breast tumors and CD45(+) infiltrating immune cells appeared to cooperate in driving CCL22 secretion, as shown clearly in cocultures of breast tumor cell lines and peripheral blood mononuclear cells (PBMC) or their supernatants. We determined that monocyte-derived IL-1β and TNF-α are key players as monocyte depletion or neutralization of these cytokines attenuated secretion of CCL22. However, when purified monocytes were used, exogenous human IFN-γ was also required to generate this response suggesting a role for IFN-γ-producing cells within PBMCs. In this setting, we found that human IFN-γ could be replaced by the addition of (i) IL-2 or K562-activated natural killer (NK) cells or (ii) resting NK cells in the presence of anti-MHC class I antibody. Taken together, our results show a dialogue between NK and tumor cells leading to IFN-γ secretion, which in turn associates with monocyte-derived IL-1β and TNF-α to drive production of CCL22 by tumor cells and subsequent recruitment of T(reg). As one validation of this conclusion in primary breast tumors, we showed that NK cells and macrophages tend to colocalize within tumors. In summary, our findings suggest that at early times during tumorigenesis, the detection of tumor cells by innate effectors (monocytes and NK cells) imposes a selection for CCL22 secretion that recruits T(reg) to evade this early antitumor immune response.

Bambusae caulis in Liquamen Suppresses the Expression of Thymus and Activation-Regulated Chemokine and Macrophage-Derived Chemokine in Human Keratinocytes due to Antioxidant Effect

Bambusae caulis in Liquamen (BCL), traditional herbal medicine used in East Asia, is known to have antioxidative and immune-regulating properties. We hypothesized that the potential antioxidant effects of BCL might suppress the production of thymus and activation-regulated chemokine (TARC) and macrophage-derived chemokine (MDC) in human keratinocytes (HaCaT cell). The immune-regulating effect of BCL was demonstrated by antioxidant capacity using DPPH analysis and DCFH-DA analysis. We found that BCL had strong ROS scavenge effect in HaCaT cell. BCL also showed suppression of IFN-γ-induced expression of TARC and MDC, activation of NF-κB, and, moreover, significant block of IFN-γ-induced degradation and phosphorylation of IκB. However, it had no effects on phosphorylation of p38 MAPK. Collectively, these results suggest that BCL may have a therapeutic potential on skin disease such as atopic dermatitis by inhibiting Th2 chemokines which is due, at least in part, to its antioxidant capacities.

Photohardening restores the impaired neutrophil responsiveness to chemoattractants leukotriene B4 and formyl-methionyl-leucyl-phenylalanin in patients with polymorphic light eruption

A failure to induce immune suppression after UV exposure has been implicated in the pathogenesis of polymorphic light eruption (PLE). This immunological resistance has been linked to an impaired neutrophil infiltration into the skin following UV exposure. Therapeutic photohardening can restore this abnormal neutrophil infiltration in PLE skin and is thought to be responsible for the prophylactic efficacy. The aim of this study was to elucidate the pathogenic mechanism of the described neutrophil deficiency in PLE. Peripheral blood neutrophil responses to the chemoattractants leukotriene B4 (LTB(4)) and formyl-methionyl-leucyl-phenylalanin (fMLP) were investigated in vitro. Samples from 10 patients with PLE before and after 6 weeks of photohardening therapy were assessed. Flow cytometry was used to measure the changes associated with neutrophil activation. We found a significantly reduced neutrophil responsiveness to LTB(4) and fMLP in PLE patients, which was restored to normal levels after phototherapy. Indeed, PLE neutrophil responsiveness to these two chemoattractants after (but not before) phototherapy was similar to that of age- and sex-matched healthy control subjects. This indicates that an abnormal chemotactic potential to neutrophils is a crucial factor in the pathogenesis of PLE. Normalization following photohardening may therefore account for the therapeutic efficacy by restoring UV-induced neutrophil skin infiltration. Our results reveal a completely novel pathogenic mechanism involved in PLE and offer unique targets for therapy.

Sulforaphane suppresses TARC/CCL17 and MDC/CCL22 expression through heme oxygenase-1 and NF-κB in human keratinocytes

Sulforaphane (4-methylsulfinylbutyl isothiocyanate, SFN) from broccoli has been used a chemopreventive photochemical as detoxification of xenobiotics and anti-inflammatory, however, there is no studies for Th2 chemokine expression through heme oxygenase-1 and NF-κB in keratinocytes. Atopic dermatitis is a chronically relapsing pruritic inflammatory skin disease. SFN is demonstrated to have anti-inflammatory and anti-oxidant effects. This study aimed to define whether and how SFN regulates Th2-related chemokine production in human HaCaT keratinocytes. The level of chemokine expression was measured by reverse transcription polymerase chain reaction (RT-PCR) and signaling study was performed by Western blot analysis. Chemokine production was determined by enzyme-linked immunosorbent assay. Pretreatment with SFN suppressed interferon-γ (IFN-γ) and tumor necrosis factor (TNF)-α- induced thymus- and activation-regulated chemokine (TARC/CCL17) and macrophage-derived chemokine (MDC/CCL22) production in HaCaT keratinocytes. SFN inhibited IFN-γ and TNF-α-induced NF-κB activation as well as STAT1 activation. Interestingly, pretreatment with SFN result in significantly suppressed IFN-γ and TNF-α-induced TARC/CCL17 and MDC/CCL22 production through the induction of HO-1. This suppression was completely abolished by HO-1 siRNA. Furthermore, Carbon monoxide, but not other end products of HO-1 activity, also suppressed IFN-γ and TNF-α-induced TARC/CCL17 and MDC/CCL22 production. These results demonstrate that SFN has an inhibitory role in IFN-γ and TNF-α-induced production of TARC/CCL17 and MDC/CCL22 in human HaCaT cells by inhibition of NF-κB activation and induction of HO-1.

The adenylyl cyclase-cAMP system suppresses TARC/CCL17 and MDC/CCL22 production through p38 MAPK and NF-kappaB in HaCaT keratinocytes

Patients with atopic dermatitis (AD) have significantly reduced plasma cAMP levels, and the cAMP level is correlated with the immunopathogenesis of AD. The production of thymus and activation-regulated chemokine (TARC/CCL17) and macrophage-derived chemokine (MDC/CCL22) in keratinocytes is significantly enhanced in patients with AD. In the present study, we investigated the in vitro effects of the adenylyl cyclase-cAMP system on IFN-gamma and TNF-alpha-stimulated production of TARC and MDC in human HaCaT keratinocytes. Both forskolin (a direct activator of adenylyl cyclase) and dibutyryl-cAMP (DBcAMP, a permeable analog of cAMP) suppressed production of TARC and MDC in parallel with the activation of NF-kappaB in IFN-gamma and TNF-alpha-stimulated HaCaT cells. Moreover, inhibition of NF-kappaB suppressed TARC and MDC production induced by IFN-gamma plus TNF-alpha. However, dideoxyforskolin, a forskolin derivative that does not activate cAMP, failed to suppress the secretion of these chemokines. An inhibitor of p38 MAPK suppressed the production of TARC and MDC in parallel to the activation of NF-kappaB in HaCaT cells. Of note, the IFN-gamma plus TNF-alpha-stimulated activation of p38 MAPK was suppressed following incubation with forskolin or DBcAMP alone. These results indicate that the adenylyl cyclase-cAMP system has an inhibitory role in IFN-gamma plus TNF-alpha-stimulated production of TARC and MDC in HaCaT keratinocytes by inhibiting NF-kappaB activation through p38 MAPK pathway, implying that the adenylyl cyclase-cAMP system could be a candidate therapeutic target of Th2-skewed skin inflammation such as AD.

Cytokine profile in human skin in response to experimental inflammation, noxious stimulation, and administration of a COX-inhibitor: a microdialysis study

Animal studies have documented a critical role for cytokines in cell signaling events underlying inflammation and pain associated with tissue injury. While clinical reports indicate an important role of cytokines in inflammatory pain, methodological limitations have made systematic human studies difficult. This study examined the utility of a human in vivo bioassay combining microdialysis with multiplex immunoassay techniques for measuring cytokine arrays in tissue. The first experiment measured cytokines in interstitial fluid collected from non-inflamed and experimentally inflamed skin (UVB). The effects of noxious heat on cytokine release were also assessed. The second experiment examined whether anti-hyperalgesic effects of the COX-inhibitor ibuprofen were associated with decreased tissue levels of the pro-inflammatory cytokines IL-1 beta and IL-6. In the first experiment, inflammation significantly increased IL-1 beta, IL-6, IL-8, IL-10, G-CSF, and MIP-1 beta. Noxious heat but not experimental inflammation significantly increased IL-7 and IL-13. In the second experiment, an oral dose of 400 and 800 mg ibuprofen produced similar anti-hyperalgesic effects suggesting a ceiling effect. Tissue levels of IL-1 beta and IL-6 were not affected after the 400mg dose but decreased significantly (44+/-32% and 38+/-13%) after the 800 mg dose. These results support the utility of explored method for tracking cytokines in human tissue and suggest that anti-hyperalgesic and anti-inflammatory effects of ibuprofen are at least partially dissociated. The data further suggest that high clinical doses of ibuprofen exert anti-inflammatory effects by down-regulating tissue cytokine levels. Explored human bioassay is a promising tool for studying the pathology and pharmacology of inflammatory and chronic pain conditions.

Epidermal chemokines and modulation by antihistamines, antibiotics and antifungals

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