Petra De Haes

1,25‐dihydroxyvitamin D3 inhibits ultraviolet B‐induced apoptosis, Jun kinase activation, and interleukin‐6 production in primary human keratinocytes

We investigated the capacity of 1,25‐dihydroxyvitamin D3 [1,25(OH)2D3] to protect human keratinocytes against the hazardous effects of ultraviolet B (UVB)‐irradiation, recognized as the most important etiological factor in the development of skin cancer. Cytoprotective effects of 1,25(OH)2D3 on UVB‐irradiated keratinocytes were seen morphologically and quantified using a colorimetric survival assay. Moreover, 1,25(OH)2D3 suppressed UVB‐induced apoptotic cell death. An ELISA, detecting DNA‐fragmentation, demonstrated that pretreatment of keratinocytes with 1,25(OH)2D3 1 μM for 24 h reduced UVB‐stimulated apoptosis by 55–70%. This suppression required pharmacological concentrations 1,25(OH)2D3 and a preincubation period of several hours. In addition, 1,25(OH)2D3 also inhibited mitochondrial cytochrome c release (90%), a hallmark event of UVB‐induced apoptosis. Furthermore, we demonstrated that 1,25(OH)2D3 reduced two important mediators of the UV‐response, namely, c‐Jun‐NH2‐terminal kinase (JNK) activation and interleukin‐6 (IL‐6) production. As shown by Western blotting, pretreatment of keratinocytes with 1,25(OH)2D3 1 μM diminished UVB‐stimulated JNK activation with more than 30%. 1,25(OH)2D3 treatment (1 μM) reduced UVB‐induced IL‐6 mRNA expression and secretion with 75–90%. Taken together, these findings suggest the existence of a photoprotective effect of active vitamin D3 and create new perspectives for the pharmacological use of active vitamin D compounds in the prevention of UVB‐induced skin damage and carcinogenesis. J. Cell. Biochem. 89: 663–673, 2003.

Molecular pathways involved in the anti-apoptotic effect of 1,25-dihydroxyvitamin D3 in primary human keratinocytes.

We previously reported that 1,25‐dihydroxyvitamin D3 [1,25(OH)2D3] protects primary human keratinocytes against ultraviolet (UV)B‐induced apoptosis. Here, we confirmed the anti‐apoptotic effect of 1,25(OH)2D3 in keratinocytes, using cisplatin and doxorubicin as apoptotic triggers. We further showed that 1,25(OH)2D3 activates two survival pathways in keratinocytes: the MEK/extracellular signal regulated kinase (ERK) and the phosphatidylinositol 3‐kinase (PI‐3K)/Akt pathway. Activation of ERK and Akt by 1,25(OH)2D3 was transient, required a minimal dose of 10−9 M and could be blocked by actinomycin D and cycloheximide. Moreover, inhibition of Akt or ERK activity with respectively a PI‐3K inhibitor (LY294002) or MEK inhibitors (PD98059, UO126), partially or totally suppressed the anti‐apoptotic capacity of 1,25(OH)2D3. Finally, 1,25(OH)2D3 changed the expression of different apoptosis regulators belonging to the Bcl‐2 family. Indeed, 1,25(OH)2D3 treatment increased levels of the anti‐apoptotic protein Bcl‐2 and decreased levels of the pro‐apoptotic proteins Bax and Bad in a time‐ and dose‐dependent way. Induction of Bcl‐2 by 1,25(OH)2D3 was further shown to be mediated by ERK and, to a lesser extent, by Akt. In conclusion, 1,25(OH)2D3 clearly protects keratinocytes against apoptosis (1) by activating the MEK/ERK and the PI‐3K/Akt survival pathways and (2) by increasing the Bcl‐2 to Bax and Bad ratio.

UVB‐induced production of 1,25‐dihydroxyvitamin D3 and vitamin D activity in human keratinocytes pretreated with a sterol Δ7‐reductase inhibitor

The skin fulfills an important role in the vitamin D photo‐endocrine system. Epidermis is not only the site of vitamin D3 photoproduction. In addition, epidermal keratinocytes contain the vitamin D receptor (VDR) and possess 25‐hydroxylase and 1α‐hydroxylase activity indicating that all components of the vitamin D system are present. We investigated whether these components cooperate in inducing vitamin D activity upon treatment with physiological UVB doses. Upon irradiation, 24‐hydroxylase mRNA was induced in keratinocytes pretreated with a sterol Δ7‐reductase inhibitor (BM15766) whereby the 7‐dehydrocholesterol content increased by 300‐fold. Transfection experiments with a vitamin D response element containing construct confirmed VDR‐dependent gene activation. Furthermore, the UVB‐dependent induction of 24‐hydroxylase was blocked by the cytochrome‐P450 inhibitor ketoconazole. The 24‐hydroxylase inducing photoproduct was transferable to unirradiated keratinocytes by medium and cellular homogenates of UVB‐irradiated, BM15766‐pretreated cells and was identified as 1,25‐dihydroxyvitamin D3 [1,25(OH)2D3] by high‐performance liquid chromatography with tandem mass spectrometric detection. Addition of vitamin D binding protein blunted UVB‐induced 24‐hydroxylase suggesting the possibility of a paracrine or autocrine role for 1,25(OH)2D3. In conclusion, epidermal keratinocytes can produce vitamin D3, convert it to 1,25(OH)2D3 and respond to it upon UVB irradiation in the absence of exogenous 7‐dehydrocholesterol and therefore contain a unique and complete photo‐endocrine vitamin D system. J. Cell. Biochem. 98: 81–92, 2006.

Disease-associated mutations identify a novel region in human STING necessary for the control of type I interferon signaling

Background Gain‐of‐function mutations in transmembrane protein 173 (TMEM173) encoding stimulator of interferon genes (STING) underlie a recently described type I interferonopathy called STING‐associated vasculopathy with onset in infancy (SAVI). Objectives We sought to define the molecular and cellular pathology relating to 3 individuals variably exhibiting the core features of the SAVI phenotype including systemic inflammation, destructive skin lesions, and interstitial lung disease. Methods Genetic analysis, conformational studies, in vitro assays and ex vivo flow‐cytometry were performed. Results Molecular and in vitro data demonstrate that the pathology in these patients is due to amino acid substitutions at positions 206, 281, and 284 of the human STING protein. These mutations confer cGAMP‐independent constitutive activation of type I interferon signaling through TBK1 (TANK‐binding kinase), independent from the alternative STING pathway triggered by membrane fusion of enveloped RNA viruses. This constitutive activation was abrogated by ex vivo treatment with the janus kinase 1/2 inhibitor ruxolitinib. Conclusions Structural analysis indicates that the 3 disease‐associated mutations at positions 206, 281, and 284 of the STING protein define a novel cluster of amino acids with functional importance in the regulation of type I interferon signaling.

UVB‐induced 1,25(OH)2D3 production and vitamin D activity in intestinal CaCo‐2 cells and in THP‐1 macrophages pretreated with a sterol Δ7‐reductase inhibitor

Epidermal keratinocytes are able to produce 1,25‐dihydroxyvitamin D3 [1,25(OH)2D3] and induce vitamin D activity upon UVB irradiation. To find out whether this property is keratinocyte specific, we investigated this characteristic in two other cell types, namely intestinal CaCo‐2 cells and the macrophage‐like differentiated THP‐1 cells. THP‐1 macrophages and preconfluent CaCo‐2 cells contain the vitamin D receptor (VDR), possess 25‐hydroxylase (CYP2R1 and CYP27A1) and 1α‐hydroxylase (CYP27B1) activity, and survive the low UVB doses essential for vitamin D3 photoproduction. Upon irradiation, 24‐hydroxylase (CYP24) mRNA is induced in both cell types pretreated with the sterol Δ7‐reductase inhibitor BM15766 whereby the 7‐dehydrocholesterol (7‐DHC) content was increased. Transfection studies in CaCo‐2 cells with a vitamin D response element‐containing construct revealed the involvement of the VDR in this UVB‐dependent CYP24 induction. The CYP24 inducing activity in BM15766‐pretreated UVB‐irradiated CaCo‐2 cells and THP‐1 macrophages was identified as 1,25(OH)2D3 by combined high‐performance liquid chromatography radioimmunoassay. Addition of vitamin D binding protein to the CaCo‐2 cells attenuated UVB‐induced CYP24 induction suggesting the possibility of a paracrine or autocrine role for the photoproduced 1,25(OH)2D3. In conclusion, preconfluent CaCo‐2 cells and THP‐1 macrophages are able to induce vitamin D activity upon UVB irradiation and hence combine all parts of the vitamin D photoendocrine system, a characteristic which is therefore not keratinocyte specific. J. Cell. Biochem.

Thalidomide: Still an important second-line treatment in refractory cutaneous lupus erythematosus?

Abstract Background: Cutaneous lupus erythematosus (CLE) can be a severe disease, characterized by extensive, disfiguring lesions and a relapsing course. Thalidomide is known as an effective treatment for CLE, however, its use is restricted by its potential side-effects. Nevertheless, it remains a valuable option to consider. Therefore, it is important to report new clinical experiences. Methods: The data of 30 patients with refractory CLE, who were treated with thalidomide, were retrospectively analyzed. The response rate was categorized as complete, partial or no response. The relapse rate and the occurrence of side-effects were registered. Results: Six patients prematurely discontinued treatment because of side-effects. The response rate was 100% in the remaining 24 patients, including 20 patients (83%) with complete response and 4 (27%) with partial response. Clinical relapse was frequent (73%) and occurred between 3 and 24 weeks after withdrawal of thalidomide. Nine patients (30%) developed peripheral neuropathy. In the majority, there was no complete resolution of the neuropathy-associated symptoms after stopping thalidomide. One patient developed a thrombosis in an artery stent. Conclusion: Because of high risk of polyneuropathy, low-dose thalidomide should be used and long-term therapy should be avoided. Therefore, it should be recommended to combine thalidomide with other treatments for CLE.

Sodium thiosulfate as a treatment for calciphylaxis: A case series

Abstract Background: Calciphylaxis is a rare disorder predominantly seen in patients with chronic kidney disease. Calcification of cutaneous vessels leads to extremely painful plaques and ulcerations. Mortality is high, sepsis being the leading cause of death. There is no standardized treatment. In the last years, administration of sodium thiosulfate (STS) has yielded some promising results. Methods: We retrospectively collected data of eight calciphylaxis patients treated with STS at the University Hospital of Leuven between June 2009 and June 2014. Results: Eight patients, of whom two without related renal risk factors, received STS treatment in different dosing schemes. Four patients (50%) achieved complete healing of skin lesions; two patients had only stabilization of the disease while experiencing pain relief. In the two remaining patients who had further progression of the disease, STS treatment led to analgesia in one patient. Overall, seven patients (87.5%) had some benefit from STS treatment. However, four patients (50%) eventually died due to causes related to calciphylaxis. STS was generally well tolerated, although almost all patients (87.5%) had metabolic acidosis. Conclusions: Treatment of calciphylaxis remains challenging. Although STS therapy, together with other treatment modalities, seems to improve disease outcome, more studies focusing on optimal dosing schemes and duration of treatment are necessary.

Airborne allergic contact dermatitis caused by disulfiram.

Keywords: airborne; alcohol; allergic contact dermatitis; CAS no. 97-77-8; connubial; rubber chemicals; systemic drugs; tetraethylthiuram disulfide; thiuram mix

Scleroderma-like cutaneous lesions during treatment with paclitaxel and gemcitabine in a patient with pancreatic adenocarcinoma. Review of literature

Chemotherapy‐induced skin sclerosis is generally not associated with other manifestations of systemic sclerosis. It is featured by skin sclerosis without visceral involvement (i.e., Raynauds phenomenon, esophageal dysmotility, and pulmonary fibrosis), temporal association with chemotherapy administration, and the absence of detectable autoantibodies. The clinical course of scleroderma‐like changes induced by paclitaxel or gemcitabine are refractory to treatment and commonly progressive, even after discontinuation of the triggering drugs.

Contact allergy to ‘bible leaf’ used in folk medicine

Tanacetum balsamita [syn. Chrysanthemum tanacetum, Chrysanthemum majus, bible leaf (USA), Costmary, or Alecost (England)] belongs to the Compositae (Asteraceae) plant family. Contact allergy to plants used to be an occupational disease (1), but because of the increasing popularity of herbal remedies, the incidence of contact dermatitis is being observed more frequently (2, 3). We report the case of a patient applying this ‘medicinal’ plant to treat a posttraumatic injury.