Loss of INK4a/Arf gene enhances ultraviolet radiation‐induced cutaneous tumor development

The CDKN2A locus encodes for tumor suppressor genes p16^INK4a and p14^Arf which are frequently inactivated in human skin tumors. The purpose of this study was to determine the relationship between loss of INK4a/Arf activity and inflammation in the development of ultraviolet (UV) radiation‐induced skin tumors. Panels of INK4a/Arf^‐/? mice and wild‐type (WT) mice were treated with a single dose of UVB (200 mJ/cm²). For long‐term studies, these mice were irradiated with UVB (200 mJ/cm²) three times weekly for 30 weeks. At the end of the experiment, tissues were harvested from mice and assayed for inflammatory biomarkers and cytokines. A single dose of UVB resulted in a significant increase in reactive oxygen species (ROS) and 8‐dihydroxyguanosine (8‐oxo‐dG) lesions in INK4a/Arf^?/? mice compared to WT mice. When subjected to chronic UVB, we found that 100% of INK4a/Arf^?/‐ mice had tumors, whereas there were no tumors in WT controls after 24 weeks of UVB exposure. The increase in tumor development correlated with a significant increase in nuclear factor (NF)‐κB, cyclooxygenase‐2 (COX‐2), prostaglandin E₂ (PGE₂) and its receptors both in UVB‐exposed skin and in the tumors. A significant increase was seen in inflammatory cytokines in skin samples of INK4a/Arf^‐/‐ mice following treatment with chronic UVB radiation. Furthermore, significantly more CD11b⁺Gr1⁺ myeloid cells were present in UVB‐exposed INK4a/Arf^‐/‐ mice compared to WT mice. Our data indicate that by targeting UVB‐induced inflammation, it may be possible to prevent UVB‐induced skin tumors in individuals that carry CDKN2A mutation.     

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.     

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.     

Cutaneous squamous cell carcinoma,thyroid cancer and Langerhans cell histiocytosis in a patient with X‐linked recessive Mendelian susceptibility to mycobacterial diseases with a nuclear factor‐κB essential modifier mutation

Nuclear factor (NF)‐κB essential modifier (NEMO), also known as IκB kinase subunit‐γ (IKKγ), is a pivotal molecule in the NF‐κB signaling pathway. Mutations of NEMO cause incontinentia pigmenti and X‐linked ectodermal dysplasia with immunodeficiency. Mendelian susceptibility to mycobacterial diseases (MSMD), which confers an almost selective predisposition to mycobacterial infection, is also caused by NEMO mutations. We herein report the first case of a patient with X‐linked recessive (XR) MSMD who developed cutaneous squamous cell carcinoma, thyroid cancer and Langerhans cell histiocytosis. The relationship between NEMO mutation and oncogenesis is discussed.     

Dihydroavenanthramide D prevents UV‐irradiated generation of reactive oxygen species and expression of matrix metalloproteinase‐1 and ‐3 in human dermal fibroblasts

Ultraviolet B (UVB) radiation induces photoageing by upregulating the expression of matrix metalloproteinases (MMPs) in human skin cells. Dihydroavenanthramide D (DHAvD) is a synthetic analog to naturally occurring avenanthramide, which is the active component in oats. Although anti‐inflammatory, anti‐atherosclerotic and antioxidant effects have been reported, the antiphotoageing effects of DHAvD are yet to be understood. In this study, we investigated the inhibitory effects of DHAvD on UVB‐induced production of reactive oxygen species (ROS) and expression of MMPs, and its molecular mechanism in UVB‐irradiated human dermal fibroblasts. Western blot and real‐time PCR analyses revealed that DHAvD inhibited UVB‐induced MMP‐1 and MMP‐3 expression. It also significantly blocked UVB‐induced ROS generation in fibroblasts. Additionally, DHAvD attenuated UVB‐induced phosphorylation of MAPKs, activation of NF‐κB and AP‐1. DHAvD regulates UVB‐irradiated MMP expression by inhibiting ROS‐mediated MAPK/NF‐κB and AP‐1 activation. DHAvD may be a useful candidate for preventing UV light‐induced skin photoageing.     

Incontinentia pigmenti in a male (XY) infant with long‐term follow up over 8 years

Incontinentia pigmenti (IP) is an X‐linked genodermatosis affecting the skin and other sites, including the teeth, nails, hair, eyes and nervous system defects in female patients. Generally lethal in males, there are only a few known cases of males surviving this condition. Nuclear factor (NF)‐κB essential modulator (NEMO), also known as inhibitor of kappa light polypeptide gene enhancer in B cells, kinase gamma (IKBKG), constitutes an essential activator of NF‐κB. Over 80% of female patients with IP carry a common deletion mutation involving exons 4–10 of the IKBKG/NEMO gene. We present the case of a male infant (XY) with IP with no concomitant complications. Polymerase chain reaction (PCR) assay showed that the exon 4–10 deletion band was significantly stronger in the skin sample than in blood. Subsequently, long‐range PCR was performed periodically to confirm the spontaneous regression of mutant cells from his blood. Over a period of 6 years, the 2.6‐kb mutant band gradually became weaker, but we did not confirm complete regression. Our patient was a healthy, 8‐year‐old male child with no complications despite the presence of a 2.6‐kb mutant band in his blood. Further follow up is necessary to assess for complications that may develop later.     

Impairment of Th cell response in Card9 knockout mice with cutaneous mucormycosis caused by Rhizopus arrhizus

Card9 is a signalling adaptor protein in the downstream of many innate pattern recognition receptors (PRRs) and exerts a significant role in antifungal immunity. To date, Card9 deficiency has been reported to be related to increased susceptibility to many fungal infections. In this study, we established mucormycosis murine model of Rhizopus arrhizus (R. arrhizus) using wild‐type (WT) mice and Card9 knockout (Card9^?/?) mice to investigate the antifungal effect of Card9 against R. arrhizus infection. Card9^?/? mice were more susceptible to R. arrhizus infection than WT mice, which could be related to the impaired NF‐κB pathway activation, local cytokine production and Th cell responses in Card9^?/? mice.     

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.     

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.     

The human IL‐17A/F heterodimer regulates psoriasis‐associated genes through IκBζ

Antagonists of IL‐17A and its receptor have proven to be highly effective in the treatment of psoriasis. However, many of the underlying molecular mechanisms involved in the pathogenesis of psoriasis are still to be determined. IκBζ (encoded by the NFKBIZ gene) plays a key role in the development of psoriasis by mediating IL‐17A‐ and IL‐17F‐driven effects. Both IL‐17A and IL‐17F expression are increased in lesional psoriatic skin. IL‐17A/A and IL‐17F/F homodimers as well as the IL‐17A/F heterodimer signal through the same receptors. The aim of this study was to characterize the role of the IL‐17A/F heterodimer in the regulation of NFKBIZ expression and in the regulation of selected psoriasis‐associated genes. We demonstrated that IL‐17A/F stimulation of human keratinocytes significantly induced NFKBIZ expression. Moreover, silencing IκBζ by siRNA revealed that IκBζ is a key regulator of IL‐17A/F‐inducible psoriasis‐associated genes, including CCL20, DEFB4, IL‐8, CHI3L1 and S100A7. In addition, IL‐17A/F‐induced NFKBIZ expression was mediated by a mechanism involving the p38 MAPK and NF‐κB signalling pathways. In conclusion, we present IκBζ as a novel key regulator of IL‐17A/F‐driven effects in psoriasis. Thus, antagonists to IL‐17A/F or IκBζ may present a targeted approach for treating psoriasis.     

Serum Th1/Th2 and macrophage lineage cytokines in leprosy; correlation with circulating CD4+ CD25highFoxP3+ T‐regs cells

Not only macrophages, T‐helper (Th)1 and Th2, but also CD4⁺ CD25^highFoxP3⁺ regulatory T cells (T‐regs) are involved in immune response to Mycobacterium leprae. We aimed to evaluate serum interleukin (IL)‐1β and IL‐12p70 (macrophage cytokines), interferon‐γ (IFN‐γ) (Th1 cytokine), IL‐4 (Th2 cytokine) and circulating CD4⁺ CD25^highFoxP3⁺ T‐regs, in untreated leprosy patients. Forty three patients and 40 controls were assessed for the mentioned cytokines using ELISA. Patients were assessed for circulating T‐regs using flow cytometry. Patients were subgrouped into tuberculoid (TT), pure neural leprosy (PNL), borderline cases, lepromatous (LL), type 1 reactional leprosy (RL1) and erythema nodosum leprosum (ENL). Serum IL‐12p70, IFN‐γ and IL‐4 were significantly higher in patients versus controls (P < 0.05). Serum IL‐4 was highest in LL and lowest in RL1 (P = 0.003). Serum IL‐1β levels was significantly higher in multibacillary versus paucibacillary patients (P = 0.006). Significantly higher T‐regs levels was detected in TT, RL1 and PNL, while the lowest levels in ENL(P < 0.001), with significant differences versus controls (P < 0.05). FoxP3 expression% was significantly lower in PNL than other patients and controls (P < 0.05). T‐regs/T‐effs was lowest in ENL(P < 0.05). IFN‐γ correlated positively with T‐regs but negatively with IL‐1β (P = 0.041&0.046 respectively), which correlated positively with T‐effs%( P = 0.05). IL‐4 correlated positively with T‐regs FoxP3 expression% (P = 0.009). We concluded that: Circulating T‐regs were increased in TT, RL1 and PNL patients, known of relatively high cell‐mediated immunity. This finding was supported by low FoxP3 expression (in PNL) and correlation between T‐regs count and IFN‐γ level. Overproduction of IL‐4 in LL may infer liability to develop ENL, with disease progression and immune hyperactivation, marked by deficient T‐regs and increased T‐regs FoxP3 expression%. IL‐1β probably has a pro‐inflammatory role in multibacillary patients as correlated with T‐effs%.     

Association between EGFR gene polymorphisms,skin rash and response to anti‐EGFR therapy in metastatic colorectal cancer patients

Cetuximab and panitumumab are epidermal growth factor receptor (EGFR) inhibitors used in metastatic colorectal cancer (mCRC). Most patients develop a papulopustular rash that may predict tumor response to treatment. EGFR gene polymorphisms may also determine tumor response and appearance of skin rash. We hypothesized an association between EGFR gene polymorphisms, papulopustular rash and response to anticancer treatment. Four EGFR polymorphisms (?216, ?191, CA‐SSR, R521K) were analysed in 51 patients with mCRC receiving anti‐EGFR. Severity of cutaneous rash and tumor response was measured following standard scales. We report an association between SNP‐216 and tumor response (P = 0.003): no tumor progression occurred in TT genotype. Moreover, 92.3% of the responder patients developed skin rash, 62.9% of them presenting a grade ≥2 (P = 0.015). Thus, although underpowered, our preliminary data suggest that SNP‐216 polymorphism of the EGFR gene could be useful in predicting tumor response and the appearance of severe skin rash might also be associated.     

Mutations in the drug resistance‐determining region of Mycobacterium lepromatosis isolated from leprosy patients in Mexico

Mycobacterium lepromatosis, an independent species from Mycobacterium leprae, has been found to be a causative agent for diffuse lepromatous leprosy (DLL) in Mexico, but remains poorly studied. Here, the drug resistance‐determining regions (DRDR) of folP1, rpoB and gyrA (conferring resistance to dapsone, rifampicin and quinolone, respectively) in M. lepromatosis from leprosy patients in Mexico were characterized. No mutations or silent mutations were found at previously characterized major sites in DRDR of M. lepromatosis. However, a non‐synonymous mutation was found in codon 54 between two major sites of the folP1 DRDR in M. lepromatosis sequences. All M. lepromatosis isolates showed CAG sequence in codon 54 of folP1. Because the next codons 53 and 55 are known as major mutation sites for drug resistance, more detailed analysis using more samples is needed to determine whether it influences susceptibility to dapsone and/or efficiency of folate biosynthesis in M. lepromatosis or not.     

Identification of PTPN22, ST6GAL1 and JAZF1 as psoriasis risk genes demonstrates shared pathogenesis between psoriasis and diabetes

The biological connections between psoriasis and diabetes have been suggested by epidemiological, immunological and genetic studies. To identify additional shared susceptibility loci and investigate shared pathogenesis between these two diseases, we genotyped 89 reported diabetes susceptibility loci in 4456 psoriasis cases and 6027 controls of Chinese population using the MassARRAY system from Sequenom. We discovered three significant associations at rs6679677 on 1p13.2 (P=6.15×10^?5, OR=5.07), rs16861329 on 3q27.3 (P=2.02×10^?4, OR=0.87) and rs849135 on 7p15.1 (P=6.59×10^?9, OR=1.78), which suggested PTPN22, ST6GAL1 and JAZF1 as novel susceptibility genes for psoriasis in Chinese population. Our findings implicated the involvement of T‐cell receptor signalling pathway in the pathogenesis of psoriasis and further confirmed the shared genetic susceptibility between psoriasis and diabetes.     

Z‐ligustilide ameliorated ultraviolet B‐induced oxidative stress and inflammatory cytokine production in human keratinocytes through upregulation of Nrf2/HO‐1 and suppression of NF‐κB pathway

Ultraviolet B (UVB), a harmful environmental factor, is responsible for a variety of skin disorders including skin inflammation through reactive oxygen species (ROS) and inflammatory mediator production. Here, we investigated the effect of Z‐ligustilide (Z‐lig), an active ingredient isolated from the medicinal plants Cnidium officinale and Angelica acutiloba, on UVB‐induced ROS generation and inflammatory mediator production in normal human epidermal keratinocytes (NHEKs) as well as its underlying mechanisms. Z‐lig significantly rescued UVB‐induced NHEKs damage in a dosage‐dependent manner. Pretreatment of NHEKs with Z‐lig inhibited UVB‐induced ROS production in NHEKs. Both silencing the nuclear factor E2‐related factor 2 (Nrf2) and the supplement of tin protoporphyrin IX (SnPP), a haeme oxygenase‐1 (HO‐1) inhibitor, cancelled the inhibitory effect of Z‐lig on UVB‐induced ROS upregulation in NHEKs. Moreover, pretreatment of NHEKs with Z‐lig reduced UVB‐induced nuclear factor kappa B (NF‐κB)‐dependent inflammatory mediators (IL‐6, IL‐8 and MCP‐1) production at both mRNA and protein level. In the presence of Z‐lig, UVB‐induced NF‐κB subunit p65 nuclear translocation was abolished, and the IκBα degradation was suppressed. Taken together, these findings suggest that Z‐lig can suppress UVB‐induced ROS generation through Nrf2/HO‐1 upregulation and inflammation by suppressing the NF‐κB pathway, suggesting that Z‐lig may be beneficial in protecting skin from UVB exposure.     

CD4+TCRγδ+FoxP3+ cells: An unidentified population of immunosuppressive cells towards disease progression leprosy patients

This study, for the first time, reveals the role of M. leprae‐specific CD4⁺TCRγδ⁺FoxP3⁺ cells in the progression and pathogenesis of leprosy. Co‐culture with CD4⁺CD25^? cells suggested the immunosuppressive nature of CD4⁺TCRγδ⁺ cells in dose‐dependent manner. Isolation of CD4⁺TCRγδ⁺ cells from leprosy patients and then culture in presence of M. leprae cell wall antigens (MLCwA) along with TGF β, IPP and IL‐2 suggested that these cells are M. leprae specific. TGF‐β‐mediated SMAD3 signalling was turned out to be major factor towards the expression of FoxP3 in these cells. SMAD3 silencing during induction of these cells barely showed the induction of FoxP3. High density of SMAD3 binding at TGFβRII in CD4⁺TCRγδ⁺FoxP3⁺ furthermore suggested the TGF‐β‐directed SMAD3 signalling in these cells. Taken together the above data, we can conclude that CD4⁺TCRγδ⁺FoxP3⁺ cells possess the potential to track the severity of the disease in leprosy patients.