NF‐κB is involved in inhibition of lipoxin A4 on dermal inflammation and hyperplasia induced by mezerein

Please cite this paper as: NF‐κB is involved in inhibition of lipoxin A₄ on dermal inflammation and hyperplasia induced by mezerein. Experimental Dermatology 2010; 19 : e286–e288. Abstract: The mechanisms by which lipoxin A₄ (LXA₄) inhibit skin inflammation remain unclear. In the present studies, the ear inflammatory model was induced by topical application of mezerein. Treatment of the mouse ear with LXA₄ exhibited the inhibitory effects on oedema, neutrophil infiltration, vascular permeability, expressions of interleukin (IL)‐1, IL‐6 and IL‐8 mRNA, DNA‐binding activity of nuclear factor‐κB (NF‐κB), and on dermal hyperplasia. NF‐κB reporter activities and nuclear translocations of NF‐κB p65 in cultured keratinocytes stimulated by mezerein were inhibited by pretreatment of the cells with LXA₄. LXA₄ reduced degradation, but not phosphorylation of IκBα in cultured keratinocytes stimulated by mezerein, suggesting that LXA₄‐attenuated IκBα degradation may restore the mezerein‐blocked inhibitory effects of IκB on nuclear translocation and DNA‐binding activity of NF‐κB. Our results demonstrated that LXA₄ displays the anti‐inflammatory and anti‐proliferative role on ear inflammatory model induced by mezerein and these effects were related with downregulation of DNA‐binding activity of NF‐κB.     

S‐allyl cysteine inhibits TNF‐α‐induced inflammation in HaCaT keratinocytes by inhibition of NF‐ κB‐dependent gene expression via sustained ERK activation

Tumor necrosis factor‐α (TNF‐α)‐induced keratinocyte inflammation plays a key role in the pathogenesis of multiple inflammatory skin diseases. Here we investigated the anti‐inflammatory effect of S‐allyl cysteine (SAC) on TNF‐α‐induced HaCaT keratinocyte cells and the mechanism behind its anti‐inflammatory potential. SAC was found to inhibit TNF‐α‐stimulated cytokine expression. Further, SAC was found to inhibit TNF‐α‐induced activation of p38, JNK and NF‐κB pathways. Interestingly, SAC was found to differentially regulate ERK MAP kinase in cells. TNF‐α‐induced transient ERK activation and SAC treatment resulted in sustained ERK activation both in the presence and absence of TNF‐α. Additionally, SAC failed to inhibit the TNF‐α‐induced expression of the pro‐inflammatory cytokines TNF‐α and IL‐1β when cells were treated with the MEK inhibitor PD98059, suggesting that the anti‐inflammatory effect of SAC is via sustained activation of the ERK pathway. Since ERK activation has been reported to negatively regulate NF‐κB‐driven gene expression and we find that SAC activates ERK and negatively regulates NF‐κB, we investigated whether there existed any crosstalk between the ERK and the NF‐κB pathways. NF‐κB‐dependent reporter assay, visualization of the nuclear translocation of NF‐κB‐p65 subunit and determination of the cellular levels of I‐κB, the inhibitor of NF‐κB, revealed that SAC inhibited TNF‐α‐induced NF‐κB activation, and PD98059 treatment reversed this effect. These results collectively suggest that SAC inhibits TNF‐α‐induced inflammation in HaCaT cells via a combined effect entailing the inhibition of the p38 and the JNK pathways and NF‐κB pathway via the sustained activation of ERK.     

Mutually enhancing anti‐inflammatory activities of dimethyl fumarate and NF‐κB inhibitors – implications for dose‐sparing combination therapies

Fumaric acid esters, dimethyl fumarate (DMF) in particular, have been established for the therapy of psoriasis and, more recently, multiple sclerosis. In the light of therapy‐limiting dose‐dependent side effects, such as gastrointestinal irritation, reducing the effective doses of FAE is a worthwhile goal. In search of strategies to maintain the anti‐inflammatory activity of DMF at reduced concentrations, we found that NF‐κB inhibition augmented key anti‐inflammatory effects of DMF in two complementary experimental settings in vitro. At non‐toxic concentrations, both proteasome inhibition with bortezomib as well as blocking NF‐κB activation through KINK‐1, a small molecule inhibitor of IKKβ‐profoundly enhanced DMF‐dependent inhibition of nuclear NF‐κB translocation in TNFα‐stimulated human endothelial cells. This resulted in significant and selective co‐operative down‐regulation of endothelial adhesion molecules crucial for leucocyte extravasation, namely E‐selectin (CD62E), VCAM‐1 (CD106) and ICAM‐1 (CD54), on both mRNA and protein levels. Functionally, these molecular changes led to synergistically decreased rolling and firm adhesion of human lymphocytes on TNF‐activated endothelial cells, as demonstrated in a dynamic flow chamber system. If our in vitro findings can be translated into clinical settings, it is conceivable that anti‐inflammatory effects of DMF can be achieved with lower doses than currently used, thus potentially reducing unwanted side effects.     

Subclinical systemic and vascular inflammation detected by 18F‐fluorodeoxyglucose positron emission tomography/computed tomography in patients with mild psoriasis

Severe psoriasis is a systemic inflammatory disease involving major arteries and internal organs. The association between psoriasis and arterial inflammation, however, has been noted mostly in patients with moderate to severe psoriasis. Therefore, it is still not clear whether mild psoriasis also increases the arterial inflammation and cardiovascular disease. In this study, we aimed to investigate systemic inflammation using ¹⁸F‐fluorodeoxyglucose positron emission tomography/computed tomography (FDG‐PET/CT) in patients with mild psoriasis. In a nested case–control study, FDG‐PET/CT findings of 10 patients with mild chronic plaque psoriasis involving a body surface area of less than 5% were compared with those of 10 age‐ and sex‐matched healthy controls. The degree of FDG uptake in the large arteries (ascending aorta, aortic arch, descending aorta, suprarenal abdominal aorta and infrarenal abdominal aorta,) and liver were analyzed using the maximum target‐to‐background ratios (TBR). There were no significant demographic differences between the psoriasis patients and the control subjects (P > 0.05). Patients with psoriasis showed higher maximum TBR than healthy controls in all examined arterial segments, with statistical significance reached in the suprarenal abdominal aorta (P < 0.05), ascending thoracic aorta (P < 0.01) and infrarenal abdominal aorta (P < 0.05), and in the liver (P < 0.05). The “candy cane sign”, which represents typical arterial inflammation of the thoracic aorta, was noted upon PET in the majority of psoriasis cases. In conclusion, mild psoriasis is also associated with arterial and hepatic inflammation, which can be readily demonstrated by using FDG‐PET/CT.     

S100A7 (psoriasin) inhibits human epidermal differentiation by enhanced IL‐6 secretion through IκB/NF‐κB signalling

Psoriasin (S100A7), a member of the S100 protein family, is a well‐known antimicrobial peptide and a signalling molecule which regulates cellular function and is highly expressed in hyperproliferative skin conditions such as atopic dermatitis (AD) and psoriasis with disrupted skin barrier function. However, its role in epidermal differentiation remains unknown. We examined the effect of S100A7 on epidermal differentiation in normal human keratinocytes (NHKs) and on a reconstituted human epidermis model. When NHKs were exposed to disruptive stimuli such as Staphylococcus aureus, ultraviolet irradiation and retinoic acid, the secretion of S100A7 into the culture medium increased and the expression of epidermal differentiation markers decreased. Treatment of NHKs with S100A7 significantly inhibited epidermal differentiation by reducing the expression of keratin 1, keratin 10, involucrin and loricrin and by increasing the expression of abnormal differentiation markers (keratin 6 and keratin 16). We verified that the MyD88‐IκB/NF‐κB signal cascade was activated via RAGE after S100A7 treatment, resulting in the upregulation of interleukin‐6. Finally, we confirmed that S100A7 is a negative regulator of epidermal differentiation using a reconstituted human epidermis model. This study suggests that S100A7‐related signalling molecules could be potent targets for recovering skin barrier function in AD and psoriasis where S100A7 is accumulated excessively.     

Guselkumab,a human interleukin‐23 monoclonal antibody in Japanese patients with generalized pustular psoriasis and erythrodermic psoriasis: Efficacy and safety analyses of a 52‐week,phase 3, multicenter,open‐label study

Generalized pustular psoriasis (GPP) and erythrodermic psoriasis (EP) are the rare and severe subtypes of psoriasis, which are often difficult to treat. The aim of this phase 3, open‐label study was to evaluate efficacy and safety of guselkumab, a human interleukin‐23 monoclonal antibody, in Japanese patients with GPP and EP. Guselkumab 50 mg was administrated to GPP (n = 10) and EP (n = 11) patients at weeks 0, 4 and thereafter every 8 weeks (q8w). Beginning at week 20, patients were escalated to 100 mg q8w if they met the dose escalation criteria. The primary end‐point was the proportion of patients achieving treatment success (Clinical Global Impression score of “very much improved”, “much improved” or “minimally improved”) at week 16. Safety evaluations included assessment of treatment‐emergent adverse events (TEAE) through week 52. At week 16, the proportions of GPP and EP patients achieving treatment success were 77.8% (7/9) and 90.9% (10/11), respectively. Furthermore, guselkumab treatment consistently showed improvement in responses of secondary end‐points such as Psoriasis Area and Severity Index, Investigator's Global Assessment, Japanese Dermatological Association severity index and improvement in body surface area involvement. Improvements in quality of life, as assessed by the Dermatology Life Quality Index, were also observed through week 52. The most commonly reported TEAE was nasopharyngitis (28.6%, 6/21). Safety findings were consistent with those observed previously in other studies. In conclusion, guselkumab treatment demonstrated efficacy and showed no safety concerns in Japanese patients with GPP and EP through week 52.     

Efficacy and safety of ixekizumab treatment for Japanese patients with moderate to severe plaque psoriasis,erythrodermic psoriasis and generalized pustular psoriasis: Results from a 52‐week,open‐label,phase 3 study (UNCOVER‐J)

Psoriasis, a chronic, immune‐mediated skin disease characterized by red, scaly plaques, affects approximately 0.3% of the population in Japan. The aim of this open‐label study was to evaluate the long‐term efficacy and safety of ixekizumab, a humanized, anti‐interleukin‐17A monoclonal antibody, in Japanese patients with plaque psoriasis (n = 78, including 11 psoriatic arthritis), erythrodermic psoriasis (n = 8) and generalized pustular psoriasis (n = 5). Ixekizumab was administrated s.c. at baseline (week 0, 160 mg), from weeks 2 to 12 (80 mg every 2 weeks), and from weeks 16 to 52 (80 mg every 4 weeks). At week 52, 92.3% of patients with plaque psoriasis achieved Psoriasis Area and Severity Index (PASI) 75, 80.8% achieved PASI 90, 48.7% achieved PASI 100, and 52.6% had remission of plaques (by static Physician Global Assessment, sPGA [0]). Difficult to treat areas of psoriasis (nail or scalp) also responded to ixekizumab. All patients with psoriatic arthritis who were assessed (5/5) achieved an American College of Rheumatology 20 response. Most patients with erythrodermic psoriasis or generalized pustular psoriasis responded to ixekizumab and the clinical outcome was maintained over 52 weeks (75% and 60% of patients achieved sPGA [0, 1] at week 52, respectively). Mostly mild or moderate treatment‐emergent adverse events were reported by 79 of 91 patients; the most common were nasopharyngitis, eczema, seborrheic dermatitis, urticaria and injection site reactions. In conclusion, 52‐week ixekizumab treatment was efficacious and well tolerated in Japanese patients with plaque psoriasis. Efficacy was also observed in patients with erythrodermic psoriasis, generalized pustular psoriasis and psoriatic arthritis.     

Activation of toll‐like receptors 2, 3 or 5 induces matrix metalloproteinase‐1 and ‐9 expression with the involvement of MAPKs and NF‐κB in human epidermal keratinocytes

Please cite this paper as: Activation of toll‐like receptors 2, 3 or 5 induces matrix metalloproteinase‐1 and ‐9 expression with the involvement of MAPKs and NF‐κB in human epidermal keratinocytes. Experimental Dermatology 2010; 19 : e44–e49. Abstract: Toll‐like receptors (TLRs) on epidermal keratinocytes are the first line of defense against microbe invasion, and matrix metalloproteases (MMPs) regulate inflammation, cell migration and wound healing. In this study, we demonstrate that the mRNA and protein expressions of MMP‐1 and MMP‐9 in human epidermal keratinocytes are induced by ligands for TLR2, TLR3 and TLR5 [Pam3CSK4, Poly(I:C) and flagellin, respectively] in a dose‐dependent manner. We also found that the ligands for TLR2, TLR3 and TLR5 activate the MAP kinases, JNK and p38 MAPK, but not ERK1/2. Furthermore, treatment with the ligands for TLR2, TLR3 and TLR5 also induced the degradation of IκB‐α and activated the nuclear translocation of NF‐κB. MMP‐1 induction by the ligands for TLR2, TLR3 and TLR5 was inhibited by pretreatment with BAY11‐7082 (NF‐κB inhibitor) or SP600125 (JNK inhibitor), whereas MMP‐9 expression was inhibited by pretreatment with BAY11‐7082, SP600125 or SB203580. These findings demonstrate that the activation of TLR2, TLR3 or TLR5 induces the expression of MMP‐1 and MMP‐9 in human epidermal keratinocytes. In addition, NF‐κB or JNK mediated the MMP‐1 expression induced by TLR2, TLR3 and TLR5, whereas NF‐κB, JNK or p38 MAPK mediated the MMP‐9 expression induced by TLR2, TLR3 and TLR5.     

MiR‐744‐3p regulates keratinocyte proliferation and differentiation via targeting KLLN in psoriasis

Psoriasis is a chronic inflammatory disease, and microRNAs have been reported to regulate the pathogenesis of psoriasis. Up‐regulated miR‐744‐3p level was identified to associate with psoriasis while the precise functions of miR‐744‐3p in psoriasis were not well‐elucidated. We first confirmed the up‐regulation of miR‐744‐3p in psoriasis by measuring its expression level in psoriatic samples. We explored the roles of miR‐744‐3p on keratinocytes proliferation and differentiation. We searched the targets of miR‐744‐3p and evaluated the roles of one target, KLLN on keratinocytes proliferation and differentiation. We confirmed the up‐regulation of miR‐744‐3p in psoriatic samples. MiR‐744‐3p promoted keratinocytes proliferation while inhibited differentiation. MiR‐744‐3p targeted KLLN and overexpression of miR‐744‐3p resulted in decreased expression of KLLN. Overexpression of KLLN prevented the effects of miR‐744‐3p on keratinocytes proliferation and differentiation. MiR‐744‐3p regulated the proliferation and differentiation of keratinocytes through targeting KLLN in psoriasis.     

Serum C‐reactive protein levels in Japanese patients with psoriasis and psoriatic arthritis: Long‐term differential effects of biologics

Psoriasis has been shown to accompany systemic inflammation. We aimed to examine serum C‐reactive protein (CRP) levels in Japanese psoriatic patients, and to elucidate their long‐term as well as short‐term changes by treatment with different biologics. A retrospective study was conducted in those who initiated and successfully continued the treatment for up to 24 months with either infliximab, adalimumab or ustekinumab, at the psoriasis special clinic of Jikei University School of Medicine. A total of 212 patients were included, 171 with plaque‐type psoriasis (PsV) and 41 with psoriatic arthritis (PsA). A statistically significant elevation of CRP values was found in the group with a Psoriasis Area and Severity Index (PASI) of 12 or more compared with the PASI of less than 12 for both PsV and PsA. The CRP‐positive patients had a higher proportion of PsA compared with the CRP‐negative patients, and they had significantly higher PASI scores. Serum CRP values declined as early as at 3 months after systemic treatment with biologics. Tumor necrosis factor (TNF)‐α antagonists did lead to a notable and sustained CRP decline up to 24 months. Infliximab showed rapid decline, while CRP decline by adalimumab treatment was time‐dependent. The interleukin‐12/23 p40 antagonist, ustekinumab, appeared to be less potent than TNF‐α antagonists in stabilizing CRP values at low levels despite good control of cutaneous lesions. In conclusion, serum CRP levels can be used to assess disease severity in Japanese psoriatic patients as a marker of systemic inflammation. TNF‐α antagonists may be more beneficial than ustekinumab in this regard.     

Dimethyl‐ and monomethylfumarate regulate indoleamine 2,3‐dioxygenase (IDO) activity in human immune cells

Fumaric acid esters (FAEs) are used as an oral treatment for psoriasis. Dimethylfumarate (DMF) and its metabolite monomethylfumarate (MMF) are regarded as the pharmacologically active moieties. Indoleamine 2,3‐dioxygenase (IDO) is the key enzyme for the metabolism of tryptophan. The kynurenine pathway is established as a major regulator of innate and adaptive immunity. Here, we investigated the effect of DMF and MMF on IDO activity and expression in human peripheral blood mononuclear cells (PBMCs). IDO activity was determined by measuring the concentration of kynurenine in the culture medium using a HPLC technique. IDO and kynureninase protein expressions were analysed by Western blot. Our results demonstrated that DMF and MMF dose‐dependently reduced the levels of L‐kynurenine in PBMCs activated by interferon‐γ (IFN‐γ). Furthermore, MMF had an inhibitory effect on IDO activity in vitro with an ED₅₀ of 10 μmol/L, a value within the therapeutic concentration range for this molecule. We also observed that IDO and kynureninase expressions were reduced in PBMCs in a dose‐dependent manner by DMF and MMF. The results of our study show that DMF and MMF (in therapeutic concentrations) inhibited IDO and kynureninase activity and expression in a NF‐κB‐dependent manner in PBMCs while also decreasing the level of L‐kynurenine in these cells. As we found that FAEs inhibit both IDO expression and enzymatic activity leading to a modulation of tryptophan degradation, we believe this effect may contribute to the clinical efficacy of this drug in psoriasis by downregulating pro‐inflammatory mediators generated by the kynurenine pathway.     

IL‐17A synergistically enhances TLR3‐mediated IL‐36γ production by keratinocytes: A potential role in injury‐amplified psoriatic inflammation

Skin injury can trigger formation of new lesions in psoriasis (Koebner phenomenon). The mechanisms through which injury exacerbates psoriasis are unclear. During wound repair, epidermal keratinocytes are activated and produce abundant IL‐36γ, further promoting the skin inflammation. IL‐17A is the cornerstone cytokine in the pathogenesis of psoriasis. We sought to investigate the effects of IL‐17A on injury‐induced keratinocyte activation and IL‐36γ production. Here, we demonstrated that dsRNA released from necrotic keratinocytes induced the expression of IL‐36γ. Silencing of TLR3 by siRNA decreased the IL‐36γ induction by necrotic keratinocyte supernatant. Co‐stimulation with dsRNA and IL‐17A synergistically increased the expression of IL‐36γ and other proinflammatory mediators (CCL20, CXCL8, DEFB4 and LCN2) in keratinocytes. The synergistic effects were not dependent on TLR3 upregulation, TNF receptor signalling and mRNA stabilization. Co‐stimulation with dsRNA and IL‐17A resulted in an accumulation of IκBζ. The synergistic upregulation of IL‐36γ and proinflammatory mediators were inhibited by IκBζ siRNA. Co‐stimulation with IL‐17A and poly(I:C) markedly activated the p38 MAPK and NF‐κB pathway, compared with poly(I:C). Blockade of p38 MAPK and NF‐κB suppressed dsRNA/IL‐17A–mediated IκBζ and IL‐36γ induction. These findings demonstrated that IL‐17A synergistically enhanced the dsRNA‐mediated IL‐36γ production through a p38 MAPK‐, NF‐κB–, and IκBζ‐dependent mechanism.     

Interleukin (IL)‐22, IL‐17, IL‐23, IL‐8, vascular endothelial growth factor and tumour necrosis factor‐α levels in patients with psoriasis before,during and after psoralen–ultraviolet A and narrowband ultraviolet B therapy

Background Several cross‐sectional studies have shown that different cytokines and growth factors are enhanced in psoriasis. Objectives We aimed to understand the role/relation of interleukin (IL)‐22, IL‐17, IL‐23, IL‐8, vascular endothelial growth factor (VEGF) and tumour necrosis factor (TNF)‐α in psoriasis vulgaris, addressing their levels and changes before, during and after psoralen–ultraviolet A (PUVA) and narrowband ultraviolet B (NB‐UVB) treatment. Methods A cross‐sectional and a longitudinal study (n = 34) – before (T0) and at 3 (T3), 6 (T6) and 12 (T12) weeks of NB‐UVB and PUVA therapy – were performed; 17 patients started NB‐UVB and 17 PUVA, and IL‐22, IL‐17, IL‐23, IL‐8, TNF‐α and VEGF levels were evaluated. Results At T0, compared with controls (n = 20), all the parameters were significantly higher in patients, except for TNF‐α. Both NB‐UVB and PUVA treatment gave, at T3, a significant decrease in TNF‐α and IL‐23; IL‐22 and IL‐17 decreased significantly at T6; all parameters and Psoriasis Area and Severity Index decreased significantly at T12. However, in both groups, at T12, VEGF was still significantly higher than control. Conclusions Psoriasis seems to be a complex disease in which the cytokine network is disturbed, namely in levels of IL‐22, IL‐17, IL‐23, IL‐8, TNF‐α and VEGF. NB‐UVB and PUVA follow‐up studies suggested that the reduction in the IL‐23/Th17 axis might be important in the pathogenic mechanisms of psoriasis. Further follow‐up studies of patients with psoriasis treated with these and other therapies could be very helpful for the understanding of the disturbance in the cytokine network in psoriasis and indirectly in its pathogenesis.     

Increased circulating anti‐α6‐integrin autoantibodies in psoriasis and psoriatic arthritis but not in rheumatoid arthritis

In psoriatic skin, laminin integrity is altered, which could lead to insufficient laminin integrin interactions, leaving the α6‐integrin exposed and possibly accessible for autoantibody production. Therefore we investigated the presence of anti‐α6‐integrin autoantibodies in the serum of patients with psoriasis vulgaris (Ps), psoriatic arthritis (PsA) and rheumatoid arthritis (RA) in comparison with healthy donors. The level of circulating anti‐α6‐integrin antibodies was determined by enzyme‐linked immunoassay using α6‐integrin fragments. Antibodies against at least one recombinant fragment were found in approximately 30% of Ps and PsA patients. In contrast, in RA patients, the frequency of antibodies was similar to healthy controls. Our study shows the presence of anti‐α6‐integrin antibodies in Ps and PsA but not in RA, which could indicate ongoing abnormal processes in the skin. Anti‐α6‐integrin autoantibodies may contribute to the formation of micro‐wounds in the skin and to the characteristic wound‐healing phenotype in psoriasis.     

Effects of tumor necrosis factor‐α, interleukin‐23 and interleukin‐17A inhibitors on bodyweight and body mass index in patients with psoriasis

Treatment with tumor necrosis factor‐α inhibitors has been reported to cause weight gain in patients with psoriasis; however, limited information is available in terms of the effects of interleukin (IL)‐23 and IL‐17A inhibitors on bodyweight (BW) in patients with psoriasis. This study aimed to investigate the effects of infliximab, ustekinumab and secukinumab on BW and body mass index (BMI) in patients with psoriasis. We retrospectively examined changes in BW and BMI among patients treated with these biologics at our hospital. At baseline, no significant differences in BW and BMI were observed among the patients treated with infliximab (n = 18), ustekinumab (n = 30) or secukinumab (n = 20). After 7 months of the therapy, significant increases in mean BW (from 71.4 to 74.3 kg) and mean BMI (from 24.7 to 25.7) were observed in the patients treated with infliximab, whereas no significant changes were observed in those treated with ustekinumab (BW, from 70.3 to 70.1 kg; BMI, from 25.4 to 25.3) or secukinumab (BW, from 69.0 to 68.9 kg; BMI, from 25.2 to 25.2). There were no differences in the proportion of the patients who showed 75% or more improvement in the Psoriasis Area and Severity Index among the three groups. These results suggest that infliximab increases BW in the patients with psoriasis, whereas ustekinumab and secukinumab do not affect the BW in these patients.