Hiroshi Uchi

Cytokines and chemokines in the epidermis

Keratinocytes (KC) produce a vast repertoire of cytokines, including interleukins, growth factors, colony stimulating factors, and chemokines. Under normal conditions, most of them are not synthesized or remain in the cytoplasm, but external stimuli, such as trauma, bacterial infections, chemical substances, or ultraviolet irradiation induce the production and release of these cytokines from KC. KC-derived cytokines regulate the immune and inflammatory responses through their receptors on KC, Langerhans cells, dermal fibroblasts and endothelial cells, and infiltrating T-cells.

An environmental contaminant, benzo(a)pyrene, induces oxidative stress-mediated interleukin-8 production in human keratinocytes via the aryl hydrocarbon receptor signaling pathway

BACKGROUND Benzo(a)pyrene (BaP) is an environmental contaminant found in cigarette smoke. It is well known that cigarette smoking exacerbates interleukin-8 (IL-8)-related inflammatory skin diseases such as psoriasis, palmoplantar pustulosis and acne. Although BaP has been shown to exert its biological effects via the aryl hydrocarbon receptor (AhR) signaling pathway, the mechanism of its inflammatory effects on skin remains unanswered. OBJECTIVE To elucidate whether or not BaP cause AhR activation and subsequent oxidative stress leading to IL-8 production in normal human epidermal keratinocytes (NHEKs). METHODS NHEKs exposed to BaP were analyzed. Immunofluorescence, real-time PCR, Western blotting, ELISA, reactive oxygen species (ROS) detection using H2DCFDA and RNA interference using si (small interfering) RNA were employed. RESULTS Immunofluorescence analysis clearly demonstrated that BaP induced nuclear translocation of AhR from cytoplasm. The AhR activation subsequently induced CYP1A1 mRNA and protein expression in a dose-dependent manner. In addition, ROS and IL-8 production were coordinately augmented by BaP, whereas this was not the case in IL-1α, IL-6, TNF-α or GM-CSF production. Knockdown of AhR expression using siRNA transfection inhibited BaP-induced-ROS and IL-8 production, suggesting that these responses are strongly dependent on the AhR signaling pathway. Furthermore, the addition of N-acetyl cystein or catalase cancelled the IL-8 production by BaP, indicating that ROS production is essential for IL-8 production. RESULTS This data highlights AhR-ROS-dependent regulation of IL-8 in NHEKs by BaP, providing a plausible explanation, at least in part, for why cigarette smoking exacerbates IL-8-related skin diseases such as psoriasis, palmoplantar pustulosis and acne.

Clinical efficacy of basic fibroblast growth factor (bFGF) for diabetic ulcer

Basic fibroblast growth factor (bFGF) has been shown to promote wound healing. The present trial evaluated the clinical efficacy of bFGF for diabetic ulcer, a type of refractory skin ulcer, and the dose-response relationship. This was designed as a randomized, double-blind, dose-ranging, placebo-controlled trial. A total of 150 patients with non-ischaemic diabetic ulcers measuring 900 mm2 or less were randomized into a placebo group (n = 51), a 0.001% bFGF group (n = 49) and a 0.01% bFGF group (n = 50), and 148 of these patients received treatment for 8 weeks or less. The efficacy evaluation was carried out on 139 patients who met the protocol in this trial. The primary outcome was the percentage of patients showing 75% or greater reductions in the area of ulcer. The area of ulcer decreased by 75% or more in 57.5% (27/47), 72.3% (34/47), and 82.2% (37/45) in the placebo, 0.001% bFGF and 0.01% bFGF groups, respectively, and differences were significant between the 0.01% bFGF and placebo groups (p = 0.025). The cure rate was 46.8% (22/47), 57.4% (27/47), and 66.7% (30/45) in the placebo, 0.001% bFGF and 0.01% bFGF groups, respectively. The findings obtained in this trial showed wound healing accelerating effects of bFGF on diabetic ulcers.

Cyclophosphamide enhances immunity by modulating the balance of dendritic cell subsets in lymphoid organs.

Cyclophosphamide (CTX), a commonly used chemotherapeutic agent can enhance immune responses. The ability of CTX to promote the proliferation of effector T cells and abrogate the function of regulatory T cells (Tregs) has been described. In this study, we examined the effects of CTX treatment on dendritic cell (DC) subsets and the subsequent outcome on the effector and suppressive arms of adaptive immunity. In secondary lymphoid tissues, tissue-derived migratory DCs (migratory DCs), lymphoid tissue-resident DCs (resident DCs), and plasmacytoid DCs (pDCs) are well described. CTX has profound and selective cytotoxic effects on CD8(+) resident DCs, but not skin-derived migratory DCs or pDCs in lymph nodes (LNs) and spleen, causing an imbalance among these DC subsets. CTX treatment increases the potency of DCs in antigen presentation and cytokine secretion, and partially inhibits the suppressor activity of Tregs. Adoptive transfer of CD8(+) DCs can reconstitute this population in regional draining LNs and abrogate the immune-enhancing effects of CTX in vivo. These findings demonstrate that CTX may improve immune responses by preferentially depleting CD8(+) lymphoid-resident DCs, which leads to diminished Treg suppression and enhanced effector T-cell function in vivo.

Identification of Ketoconazole as an AhR-Nrf2 Activator in Cultured Human Keratinocytes: The Basis of Its Anti-Inflammatory Effect

Ketoconazole (KCZ) has been shown to exhibit anti-inflammatory effects in addition to its inhibitory effects against fungi; however, the underlying molecular mechanism remains poorly understood. Aryl hydrocarbon receptor (AhR), a receptor that is activated by polycyclic aromatic hydrocarbons (PAHs) and halogenated aromatic hydrocarbons such as dioxin, is a sensor of the redox system against oxidative stress and regulates nuclear factor-erythroid 2-related factor-2 (Nrf2), a master switch of the redox machinery. To clarify whether KCZ modulates AhR-Nrf2 function leading to redox system activation, cultured human keratinocytes were treated with KCZ. Confocal microscopic analysis revealed that KCZ induced AhR nuclear translocation, resulting in the upregulation of CYP1A1 mRNA and protein expression. Furthermore, KCZ actively switched on Nrf2 nuclear translocation and quinone oxidoreductase 1 expression. Tumor necrosis factor-α- and benzo(a)pyrene (BaP)-induced reactive oxidative species (ROS) and IL-8 production were effectively inhibited by KCZ. Knockdown of either AhR or Nrf2 abolished the inhibitory capacity of KCZ on ROS and IL-8 production. In addition, KCZ-induced Nrf2 activation was canceled by AhR knockdown. Moreover, KCZ inhibited BaP-induced 8-hydroxydeoxyguanosine and IL-8 production. In conclusion, the engagement of AhR by KCZ exhibits the cytoprotective effect mediated by the Nrf2 redox system, which potently downregulates either cytokine-induced (AhR-independent) or PAH-induced (AhR-dependent) oxidative stress.

Propionibacterium acnes-induced IL-8 production may be mediated by NF-κB activation in human monocytes

Propionibacterium acnes (P. acnes) causes an inflammatory acne that is characterized by massive neutrophilic infiltration. IL-8 is thought to play an important role in the pathophysiology of P. acnes, although the mechanisms by which P. acnes up-regulates the release of IL-8, a neutrophilic chemokine, from target cells is not well understood. In this study, we investigated the mechanisms through which heat-killed P. acnes induces IL-8 production in THP-1 cells (a human monocytic cell line). We found that P. acnes is able to directly induce IL-8 production and IL-8 mRNA expression in human monocytic cells in a dose- and time-dependent manner through a mechanism requiring transcription factor NF-kappaB activation. Additionally, P. acnes-induced IL-8 secretion was inhibited by roxithromycin, a macrolide antibiotic, and its inhibitory effect seemed to be partially associated with the inhibition of P. acnes-induced NF-kappaB activation. This is the first study to show that NF-kappaB activation is involved in the IL-8 production of monocytic cells stimulated by P. acnes.

Histamine-induced IL-6 and IL-8 production are differentially modulated by IFN-γ 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.

Unraveling the Complex Relationship Between Cancer Immunity and Autoimmunity: Lessons from Melanoma and Vitiligo

A relationship between melanoma and vitiligo, a skin disorder characterized by the loss of melanocytes, has been postulated for many decades. In some cases, vitiligo is almost certainly a manifestation of autoimmune-mediated destruction of melanocytes. Melanocytes and melanoma cells share melanocyte differentiation antigens. Based on a number of observations, de novo vitiligo developing in patients with melanoma has been regarded as a sign of good prognosis. The immune system tolerates or ignores differentiation antigens because these antigens are self-derived. Therefore, immune tolerance or ignorance must be overcome to prime naive T and B cells to induce cancer immunity and autoimmunity against melanocyte differentiation antigens. Mouse models of concurrent melanoma and autoimmune vitiligo have revealed strategies to overcome immune ignorance or tolerance to melanocyte differentiation antigens: immunization with self-antigens as altered self (e.g., orthologues or mutated versions), expression in viral vectors, passive immunization with antibodies or T cells, incorporating potent adjuvants into active immunization, and blockade or removal of a downregulatory mechanism. Extensive investigations into the mechanisms that lead to tumor immunity and autoimmunity elicited by certain differentiation antigens have further revealed a variety of distinct cellular and molecular requirements, which are redundant and alternative.

Clinicopathologic and prognostic significance of SATB1 in cutaneous malignant melanoma

BACKGROUND Special AT-rich sequence-binding protein-1 (SATB1), a new type of gene regulator, has been reported to be expressed in several human cancers and may have malignant potential. However, no data on SATB1 expression and its relationship to tumor progression in cutaneous malignant melanoma (CMM) has yet been reported. OBJECTIVE We examined the immunohistochemical expression of SATB1 in CMM to determine whether it could serve as a prognostic marker. METHODS A total of 97 samples of primary CMM and controls were immunostained for SATB1. The following clinicopathologic variables were evaluated: age, gender, subtype, SATB1 expression, Breslow thickness, Clark level, presence of ulceration, lymph node metastasis, distant metastasis, and survival. Statistical analyses were performed to assess for associations. Several parameters were analyzed for survival using the Kaplan-Meier method and Cox proportional-hazards model. RESULTS Forty cases (85.1%) of CMM showed positive staining for SATB1 by immunohistochemistry. The intensity of SATB1 staining was significantly higher in CMM than in nevus NV and normal skin (NS) (P < 0.01). High SATB1 expression was significantly correlated with Breslow thickness, Clark level, mortality, presence of ulceration, and lymph node metastasis (P < 0.01). Moreover, Kaplan-Meier analysis revealed that SATB1 overexpression was significantly associated with worse survival (P < 0.01). Further univariate analysis and multivariate regression analysis indicated that SATB1 expression was an independent prognostic marker for CMM (P = 0.03). CONCLUSIONS The overexpression of SATB1 correlated with metastatic potential of CMM and is a novel independent prognostic marker for predicting outcome.

Long-term effects of polychlorinated biphenyls and dioxins on pregnancy outcomes in women affected by the Yusho incident.

Background Maternal exposure to polychlorinated biphenyls (PCBs) is associated with increased proportions of spontaneous abortion and stillbirth in animal studies. In Japan in 1968, accidental human exposure to rice oil contaminated with PCBs and other dioxin-related compounds, such as polychlorinated dibenzofurans (PCDFs), led to the development of what was later referred to as Yusho oil disease. Objective The aim of this study was to investigate the association of maternal PCB and dioxin exposure with adverse pregnancy outcomes in Yusho women. Methods In 2004, we interviewed 214 Yusho women (512 pregnancies) about their pregnancy outcomes over the past 36 years. Pregnancy outcomes included induced abortion, spontaneous abortion, preterm delivery, and pregnancy loss. Results In pregnancy years 1968–1977 (within the first 10 years after exposure), the proportions of induced abortion [odds ratio adjusted for age at delivery (ORadj) = 5.93; 95% confidence interval (CI), 2.21–15.91; two-tailed p < 0.001) and preterm delivery (ORadj = 5.70; 95% CI, 1.17–27.79; p = 0.03) were significantly increased compared with the proportions in pregnancy years 1958–1967 (10 years before the incident). Spontaneous abortion (ORadj = 2.09; 95% CI, 0.84–5.18), and pregnancy loss (ORadj = 2.11; 95% CI, 0.92–4.87) were more frequent (OR = 2.18; 95% CI, 1.02–4.66), but these were not significant (p = 0.11 and p = 0.08, respectively) in pregnancy years 1968–1977. We found no significant increases in the proportions of these adverse pregnancy outcomes in pregnancies occurring during 1978–1987 or 1988–2003 compared with those in pregnancies before 1968. Conclusion High levels of PCB/PCDF exposure had some adverse effects on pregnancy outcome in Yusho women.