[Translation into French and republication of: "Management of venous thromboembolic disease in patients with malignant brain tumours"]. / Traduction et republication de : « Prise en charge de la maladie thromboembolique veineuse chez les patients atteints de tumeurs cérébrales malignes ¼.

This article addresses the management of venous thromboembolism in patients with malignant brain tumours, including both primary and secondary (metastatic) tumours. The available data on patients on venous thromboembolism recurrence and bleeding risks in patients with brain tumours is limited, since these patients have been excluded from most randomised, interventional, head-to-head, clinical trials comparing low molecular weight heparins to vitamin K antagonists or to direct oral factor Xa inhibitors. More information is available from retrospective observational studies, which however were generally small, and carried a high risk of confounding. Their findings suggest that direct factor Xa inhibitor use is associated with lower rates of intracranial haemorrhage compared with low molecular weight heparins. Overall, the safety profile of direct oral factor Xa inhibitors when used to prevent venous thromboembolism recurrence in patients with either primary or secondary brain tumours appears to be favourable. The available data are in favour of using an anticoagulant at a full therapeutic dose in patients with primary and secondary brain tumours experiencing a venous thromboembolism, although they are not yet sufficiently robust to permit recommending a direct factor Xa inhibitor over low-molecular weight heparin.

[Translation into French and republication of: "Management of cancer-associated thromboembolism in vulnerable population"]. / Traduction et republication de : « Prise en charge de la maladie thromboembolique veineuse associée au cancer chez les populations vulnérables ¼.

Although all patients with cancer-associated thrombosis (CAT) have a high morbidity and mortality risk, certain groups of patients are particularly vulnerable. This may expose the patient to an increased risk of thrombotic recurrence or bleeding (or both), as the benefit-risk ratio of anticoagulant treatment may be modified. Treatment thus needs to be chosen with care. Such vulnerable groups include older patients, patients with renal impairment or thrombocytopenia, and underweight and obese patients. However, these patient groups are poorly represented in clinical trials, limiting the available data on which treatment decisions can be based. Meta-analysis of data from randomised clinical trials suggests that the relative treatment effect of direct oral factor Xa inhibitors (DXIs) and low molecular weight heparin (LMWH) with respect to major bleeding could be affected by advanced age. No evidence was obtained for a change in the relative risk-benefit profile of DXIs compared to LMWH in patients with renal impairment or of low body weight. The available, albeit limited, data do not support restricting the use of DXIs in patients with TAC on the basis of renal impairment or low body weight. In older patients, age is not itself a critical factor for choice of treatment, but frailty is such a factor. Patients over 70 years of age with CAT should undergo a systematic frailty evaluation before choosing treatment and modifiable bleeding risk factors should be addressed. In patients with renal impairment, creatine clearance should be assessed and monitored regularly thereafter. In patients with an eGFR less than 30mL/min/1.72m2, the anticoagulant treatment may need to be adapted. Similarly, platelet count should be assessed prior to treatment and monitored regularly. In patients with grade 3-4, thrombocytopenia (less than 50,000platelets/µL) treatment with a LMWH at a reduced dose should be considered. For patients with CAT and low body weight, standard anticoagulant treatment recommendations are appropriate, whereas in obese patients, apixaban may be preferred.

Long-term use of tinzaparin for the treatment of cancer-associated thrombosis in clinical practice: Insights from the prospective TROPIQUE study.

BACKGROUND: Real word data on the efficacy and safety of long-term use of tinzaparin for the treatment of cancer-associated thrombosis (CAT) are scarce. METHODS: We performed a post-hoc analysis of all cancer patients included in the prospective multicenter observational TROPIQUE study who received long-term treatment with tinzaparin for a first venous thromboembolism (VTE) event. We evaluated the patterns of anticoagulant prescription, the adherence to clinical practice guidelines (CPGs) for the treatment of CAT, and the clinical outcomes within a 6-month follow-up. RESULTS: In total, 301 patients were included in this post-hoc analysis. At study entry, their mean age was 64.6±11.9years and 143 (47.5%) patients were men. The most frequent cancer type was gastrointestinal (23.9%), followed by breast (17.9%) and lung (15.3%) cancer. At time of VTE diagnosis, 164 (57.8%) patients had metastatic disease and 245 (81.42%) were receiving chemotherapy. Based on the aggregation of all study pre-defined criteria, tinzaparin prescription was fully compliant with CPGs in 219 (72.8%) patients. The mean effective treatment duration with tinzaparin was 6.07±0.17months. At 6-month follow-up, the cumulative incidence of recurrent VTE was 5.4% (95% CI: 3.2-9.2%) and the cumulative incidence of major bleeding was 5.8% (95% CI: 3.6-9.6%). Clinical outcomes tended to differ across different types of cancer. Death from any cause occurred in 102 (33.9%) patients, mainly related to cancer progression. CONCLUSIONS: This post-hoc analysis of TROPIQUE confirms the favorable benefit-risk ratio of tinzaparin for the long-term treatment of CAT.

Patient education program at the forefront of cancer-associated thrombosis care.

INTRODUCTION: Treatment of cancer-associated thrombosis (CAT) requires specific approaches, although it is well codified in most cases. Current national and international (International Initiative on Cancer and Thrombosis, ITAC) Clinical Practice Guidelines (CPG) recommend the use of low-molecular-weight heparin (LMWH) over 6 months as first treatment option, and anticoagulation should be maintained thereafter as long as cancer is active. Since compliance improves when patients understand their disease and related treatments, we created a dedicated patient education program (PEP) for CAT, aiming to improve quality of care. METHODS: Retrospective analysis of all patients who voluntarily joined the PEP for CAT from 2014 to 2020. RESULTS: In total, 182 cancer patients (median age, 64.9 years) were included, 53.3% with metastatic disease. A total of 528 PEP sessions (median, 3 per patient) were delivered. After PEP completion, the rate of self-injections or those performed at home by a relative had increased from 49.1% to 59.8% (P=0.05). Quality of life had improved significantly (P=0.025) and 90.0% of patients reported adhering to anticoagulant therapy. CONCLUSION: Implementation of a structured and personalized PEP for CAT is feasible, allowing to improve cancer patient empowerment, adherence to CAT treatment and quality of life. The Groupe francophone et cancer (GFTC) members aim at facilitating access to CAT-PEP for both patients and caregivers and use of the multi-language ITAC-CPG mobile app (free access: www.itaccme.com) to improve the care and quality of life of patients with CAT.

Management of cancer-related thrombosis in the era of direct oral anticoagulants: A comprehensive review of the 2019 ITAC-CME clinical practice guidelines. On behalf of the Groupe Francophone Thrombose et Cancer (GFTC).

Venous thromboembolism (VTE) is a common disease complication in cancer patients and the second cause of death after cancer progression. VTE management and prophylaxis are critical in cancer patients, but effective therapy can be challenging because these patients are at higher risk of VTE recurrence and bleeding under anticoagulant treatment. Numerous published studies report inconsistent implementation of existing evidence-based clinical practice guidelines (CPG), including underutilization of thromboprophylaxis, and wide variability in clinical practice patterns across different countries and various practitioners. This review aims to summarize the 2019 ITAC-CME evidence-based CPGs for treatment and prophylaxis of cancer-related VTE, which include recommendations on the use of direct oral anticoagulants specifically in cancer patients. The guidelines underscore the gravity of developing VTE in cancer and recommend the best approaches for treating and preventing cancer-associated VTE, while minimizing unnecessary or over-treatment. Greater adherence to the 2019 ITAC guidelines could substantially decrease the burden of VTE and improve survival of cancer patients.

[Treatment of cancer associated thrombosis: Which role for direct oral anticoagulants in 2018?] / Traitement curatif de la maladie thromboembolique veineuse chez les patients atteints de cancer : quelle place pour les anticoagulants oraux directs en 2018 ?

Low molecular weight heparin (LMWH) for at least 3-6 months is the current standard of care for the treatment of cancer associated venous thromboembolism (VTE). Anticoagulation should be continued as long as the cancer is active. In recent years, several direct-acting oral anticoagulants (DOACs) have been approved for the treatment of VTE in the general population. These drugs have progressively emerged as attractive alternatives with the potential to overcome the limitations of LMWH. Due to the lack of high quality prospective data, DOACs are currently not recommended for the treatment of cancer associated VTE yet. Indeed, evidence supporting the use of DOACs in this specific population remains limited, and concerns have been raised about their safety and efficacy in this setting. However, a pattern of increased use of DOACs has been observed in the cancer population. Meta-analyses of Phase III trials of DOACs in VTE as well as analysis of large health care claims databases and non-controlled retrospective studies suggest that DOACs might have similar effectiveness and safety to LMWH for the management of cancer associated VTE. Results from 2 randomized clinical trial (RCT), HOKUSAI-Cancer and SELECT-D, were recently released. Based on a meta-analysis of these 2 RCTs, compared to LMWH, DOACs had lower 6 month recurrent VTE but higher major bleeding. Thus, DOACs should be used with caution in cancer patients and a careful evaluation of the risks and benefits for individual patients is warranted. Ongoing studies will provide much needed evidence to guide clinical care.

[Venous thromboembolism and pancreatic cancer]. / Maladie thromboembolique veineuse et cancer du pancréas.

Pancreatic cancer (PC) is a devastating malignancy with an overall 5-year survival of 8% for all stages combined. Most of the PC patients diagnosed have an advanced disease (40%) or metastatic stage (40%), which eliminates surgery as a potentially curative treatment. The disease course is often complicated by venous thromboembolism (VTE) events, which per se account for significant morbidity and mortality, with significantly worsen survival. PC is associated with the highest risk of VTE among all cancer patients. We review the literature data to address the incidence and clinical outcomes of VTE in PC patients. VTE incidence varies from 5 to 41% according to epidemiological studies and is as high as 57% in postmortem series. Since 2013, international clinical practice guidelines recommend primary thromboprophylaxis with a grade 1B level of evidence as an adjuvant therapy in advanced PC. A recent meta-analysis of randomized controlled trials investigating the benefit and risk of low-molecular-weight heparins (LMWH) in ambulatory advanced PC patients under chemotherapy showed that the incidence of VTE was 2.1% in patients treated with LMWH and 11.2% in controls (risk ratio, 0.18; 95% CI, 0.083-0.39; P<0.0001). In conclusion, improved earlier diagnosis and effective management of VTE, a frequent and life-threatening complication in PC, is warranted to improve PC patient outcomes.

Production of platelet-rich plasma gel from elderly patients under antithrombotic drugs: Perspectives in chronic wounds care.

Platelet-Rich Plasma (PRP) is an autologous biological therapy obtained by centrifuging the patient's own blood to concentrate platelets. The addition of autologous thrombin and calcium chloride to PRP allows the production of a semi-solid form called PRP gel. PRP gel is increasingly used in a variety of tissue defects and predominantly in the management of non-healing chronic wounds. The topical application of PRP gel seems promising due to the capability of platelets to store and secrete growth factors (GF), fibrin and cytokines, which are essentials for wound healing. Most patients who suffered from chronic wounds are elderly patients with co-morbidities and polypharmacy including antithrombotic drugs such as antiplatelet agents (AP) or anticoagulants (AC), which could hamper the feasibility of this autologous platelet-derived therapy. To date, no study has investigated PRP gel formation in patients with AP or AC. The aim of this study was to evaluate the influence of AP or AC drugs on the production of PRP gel formation from elderly patients. Different biological characteristics were determined to qualify the production of PRP gel from such patients (Interquartile range (IQR) = 75-92 years) compared to healthy volunteers (IQR = 23-37 years). No significant difference was observed in the volume, composition (quantity of platelets, leukocytes and red blood cells) and functionality of platelets from PRP except a higher ADP-induced P-selectin expression in healthy donors compared with elderly patients. Autologous thrombin characteristics were similar in the two groups. Gel time formation (IQR: 120-195 seconds for controls and 135-210 seconds for elderly patients) and final composition of PRP gel were not significantly modified. Concentrations of theoretical thrombin generated in the serum and in the gel were inversely correlated with the time of formation of PRP gel (r2 = 0.57, p = 0.012). Altogether these data indicate that PRP gel preparation is not impacted by the use of antithrombotic drugs. Such results support the feasibility of using this innovative autologous biotherapy in the management of elderly patients with non-healing chronic wounds.

[New international guidelines for curative treatment and prophylaxis for venous thromboembolism (VTE) in cancer patients and the dedicated smartphone application]. / Nouvelles recommandations internationales pour le traitement curatif et prophylactique de la maladie thromboembolique veineuse chez les patients atteints d'un cancer et application dédiée pour smartphone.

Venous thromboembolism (VTE) is a frequent and serious complication in cancer patients, and the second leading cause of death in this setting. Cancer patients are also more likely to present recurrent VTE and major bleeding while taking anticoagulants. Management of VTE in these patients is always challenging and remains suboptimal worldwide. In 2013, the International Initiative on Thrombosis and Cancer (ITAC-CME) released international guidelines for the treatment and prophylaxis of VTE and central venous catheter-associated thrombosis, based on a systematic review of the literature ranked according to the Grading of Recommendations Assessment, Development, and Evaluation scale. An update of these ITAC-CME consensus guidelines, including the use of direct oral anticoagulants, was recently published. In this review, we summarize these updated guidelines. Better adherence to the international guidelines, involving an adequate educational and active implementation strategies, will substantially decrease the burden of VTE and allow to increase survival in cancer patients.

PO-34 - Optimal doses of tinzaparin to reduce both cancer-associated thrombosis and tumor growth in a mouse model of ectopic pancreatic syngeneic tumor.

INTRODUCTION: In clinical studies, thromboprophylaxis with low-molecular-weight heparins (LMWHs) has been demonstrated to reduce the risk of venous thromboembolism and to improve outcomes in cancer patients. Moreover, preclinical models have previously suggested that LMWHs may also offer additional benefits through direct antitumor properties. However, the optimal doses of LMWHs that may prevent both cancer-related thrombosis and tumor development are yet unknown. AIM: The goal of this study was to determine the optimal doses of tinzaparin that may prevent both cancer-related thrombosis and tumor development in a syngeneic ectopic model of pancreatic cancer. MATERIALS AND METHODS: The optimal doses of tinzaparin to generate a plasma anti-Xa activity >0.2IU/mL were determined in vivo following injection into wild type mice.The syngeneic ectopic model of cancer was induced in wild-type mice using the mouse pancreatic cancer cell line Panc02. Mice were injected daily with 200, 300IU/kg or 400IU/kg, or placebo from day 8 to 25 following tumor induction. Kinetics of thrombus formation and fibrin generation were determined in real time by digital real time intravital microscopy in mice bearing a tumor treated with tinzaparin or placebo. The growth of the tumor and the bleeding times were measured and compared in the different groups of mice. RESULTS: Plasma anti-Xa levels <0.2IU/mL were observed with tinzaparin doses ranging from 0 to 150IU/kg, whereas plasma anti-Xa activities >0.2IU/mL were obtained with >200IU/kg tinzaparin doses. At day 25 following tumor induction, the kinetics of thrombosis were not affected in mice treated with daily 200IU/kg tinzaparin compared to controls whereas it was strongly affected in mice treated with daily 300 and 400IU/kg tinzaparin. Interestingly, a significant decrease in tumor growth was observed in mice treated with 200, 300 and 400IU/kg tinzaparin in comparison to controls, with no significant difference between these groups. Bleeding times were similar to control mice in mice treated with 200IU/kg tinzaparin, but significantly increased in mice treated with 300IU/kg and 400IU/kg tinzaparin. CONCLUSIONS: At the dose of 200IU/kg, tinzaparin treatment significantly inhibits tumor growth but did not affect the thrombotic phenotype in mice developing a cancer. When 300 and 400IU/kg dose are used, tinzaparin treatment decreases both cancer-related thrombotic phenotype and tumor growth, but at the price of a significant increase in the bleeding time.

Interaction between the C-260T polymorphism of the CD14 gene and the plasma IL-6 concentration on the risk of myocardial infarction: the HIFMECH study.

Experimental and clinical observations suggest that innate immunity plays a major role in the pathogenesis and progression of atherosclerosis. A common C-260T polymorphism in the promoter of the CD14 gene, the trans-membrane receptor of lipopolysaccharides, has been inconsistently associated with coronary heart disease. Our objective was to evaluate the contribution of the CD14 polymorphism to the inflammatory response and to the risk of myocardial infarction (MI). We used an European case-control study, the HIFMECH study, comparing 533 men with MI and 575 sex- and age-matched controls. Associations between genotype and disease outcome, according to interleukin-6 (IL-6) and C-reactive protein (CRP) levels, were assessed using conditional logistic regression. The CD14/C-260T polymorphism was associated with plasma IL-6 levels, T/T subjects having higher plasma levels than C/C in cases but not in controls (mean+/-S.D.: 2.04+/-1.37 versus 1.70+/-1.15, p=0.01; 1.20+/-0.75 versus 1.35+/-0.88, p=0.31, respectively). Overall, the CD14/C-260T polymorphism was not associated with the risk of MI. However, in individuals with IL-6 plasma levels in the highest tertile, T allele carriers had a higher risk of MI than C/C (OR: 1.85; CI 95 1.05-3.25). IL-6 increased the risk of MI in carriers of the T allele (OR for first versus third IL-6 tertile: 4.02; CI 95 2.24-7.21), but not in C/C (OR: 0.75; CI 95 0.32-1.74, p=0.004 for interaction). The data indicate a role for CD14/C-260T in MI. The risk mediated by the polymorphism is highly dependent on IL-6 plasma levels.

Contrasting effects of an ultraviolet B and an ultraviolet A tanning lamp on interleukin-6, tumour necrosis factor-alpha and intercellular adhesion molecule-1 expression.

BACKGROUND: Recent studies have demonstrated that a tanning lamp emitting predominantly ultraviolet (UV) A induces significant yields of the type of potentially mutagenic DNA damage that are associated with the onset of skin cancer (i.e. cyclobutane pyrimidine dimers). UV-induced immunosuppression is also an important event leading to skin cancer. OBJECTIVES: To the modulation of key immunological molecules following exposure to a broad-spectrum UVB lamp and a predominantly UVA-emitting tanning lamp using model in vitro systems. METHODS: We compared secretion and mRNA expression of interleukin (IL)-6 and tumour necrosis factor (TNF)-alpha in normal human epidermal keratinocytes, and interferon (IFN)-gamma-induced intracellular adhesion molecule (ICAM)-1 in normal human fibroblasts irradiated in vitro with a broad-spectrum UVB lamp or with a Philips 'Performance' tanning lamp. RESULTS: With broad-spectrum UVB irradiation, upregulation of IL-6 and TNF-alpha mRNA was detected 6 h after irradiation, and a dose-dependent increase of cytokines in the supernatants of irradiated cells was found 24 h after irradiation. In contrast, there was no cytokine secretion and little evidence for mRNA upregulation following exposure to a tanning lamp. When cells were exposed first to broad-spectrum UVB, then the tanning lamp, UVB-induced cytokine secretion was inhibited, although mRNA levels were upregulated to a level close to that observed with UVB alone. By using a Schott WG 320 nm filter to attenuate the level of UVB relative to UVA emitted by the tanning lamp, the inhibition of cytokine secretion was shown to be associated with UVA exposure. Both UV sources inhibited IFN-gamma-induced ICAM-1 mRNA expression in a dose-dependent fashion. By using a Schott WG 335 nm filter, inhibition of ICAM-1 mRNA expression by the tanning lamp was shown to be associated with UVB exposure. CONCLUSIONS: These results suggest that UV sources emitting different levels of UVA and UVB have differential effects on the modulation of different immunoregulatory molecules, and indicate that there are potential interactions between these wavelengths.

Ultraviolet-B-induced apoptosis and cytokine release in xeroderma pigmentosum keratinocytes.

We have assessed the ability of xeroderma pigmentosum and normal keratinocytes grown out from skin biopsies to undergo apoptosis after irradiation with ultraviolet B. Keratinocytes have been studied from xeroderma pigmentosum complementation groups A (three biopsies), C (three biopsies), D (one biopsy), xeroderma pigmentosum variant (two biopsies), and Cockayne syndrome (one biopsy). The three xeroderma pigmentosum group A and the xeroderma pigmentosum group D samples were at least six times more sensitive than normal cells to ultraviolet B-induced apoptosis. The xeroderma pigmentosum variant samples showed intermediate susceptibility. Xeroderma pigmentosum group C samples proved heterogeneous: one showed high sensitivity to apoptosis, whereas two showed near normal susceptibility. The Cockayne syndrome sample showed the high susceptibility of xeroderma pigmentosum groups A and D only at a higher fluence. These results suggest that the relationships between repair deficiency, apoptosis, and susceptibility to skin cancer are not straightforward. Ultraviolet B-induced skin cancer is also thought to be due in part to ultraviolet B-induced impairment of immune responses. The release of the inflammatory cytokines interleukin-6 and tumor necrosis factor-alpha from cultured xeroderma pigmentosum keratinocytes tended to occur at lower fluences than in normals, but was less extensive, and was more readily inhibited at higher fluences of ultraviolet B.

Apoptosis and cytokine release induced by ionizing or ultraviolet B radiation in primary and immortalized human keratinocytes.

We have compared the induction of apoptosis and cytokine release by UVB and gamma-radiation in primary (untransformed) and in two immortalized human epithelial/keratinocyte cell lines, HaCaT and KB (KB is now known to be a subline of the ubiquitous keratin-forming tumour cell line HeLa and we therefore designate it HeLa-KB). In both the primary and the immortalized cell lines apoptosis and release of the inflammatory cytokine interleukin-6 are induced rapidly following UVB irradiation. In contrast, only the immortalized cells undergo apoptosis and release interleukin-6 after gamma-irradiation and here the onset of apoptosis and cytokine release are delayed. The same distinction between primary and immortalized cells was observed when double-strand breaks were induced with the anticancer drug mitoxantrone, which stabilizes topoisomerase II-cleavable complexes. We suggest that immortalization may sensitize keratinocytes to the apoptogenic effect of ionizing radiation or mitoxantrone by deregulating normal cell cycle checkpoints. In both human keratinocytes and fibroblasts, cell killing, as assayed by loss of colony-forming ability, is not coupled to apoptosis. Immortalization increases resistance to gamma-radiation killing but sensitizes to apoptosis. In contrast, although immortalization also sensitizes to UVB-induced apoptosis, it does not affect UVB-induced cell killing. Apoptosis unambiguously indicates death at the single cell level but clonal cell survival integrates all the cellular and genetic processes which prevent or permit a scorable clone to develop.

Regulation of the promoter for human immunoglobulin gamma3 germ-line transcription and its interaction with the 3'alpha enhancer.

The mechanism underlying the differential regulation of switching to human IgG subclasses is still largely unknown. We demonstrate that the region upstream of the initiation sites for gamma3 germ-line (GL) transcripts contains a functional promoter which is synergistically induced by IL-4, antibody to CD40 and phorbol dibutyrate in transient transfection assays in the human DG75 cell line. Linker-scanning mutations identified multiple elements in the 3' half of the evolutionarily conserved sequence that are required for inducibility. Electrophoretic mobility shift assays showed that Stat6 and NF-kappaB p50 / p65 are induced after stimulation, and bind to specific sequence motifs within the promoter. Overexpression of Stat6, NF-kappaB p50 / p65 and C / EBPgamma synergistically induced the GL gamma3 promoter. Insertion of DNA segments from the human 3' IgH regions, which may function as a locus control region for switch recombination, greatly activated the promoter in an orientation-independent manner. Duplication of the enhancer fragments resulted in a further increase of promoter activity. The greater enhancement of the HS1,2 fragment from the 3' alpha1 rather than the alpha2 locus may suggest a mechanistic explanation for the differential expression of various isotypes.

The 0.8% ultraviolet B content of an ultraviolet A sunlamp induces 75% of cyclobutane pyrimidine dimers in human keratinocytes in vitro.

Tanning lamps, emitting predominantly ultraviolet (UV) A, are used widely throughout the U.K. and other countries, but little is known about the long-term risks associated with their use, especially with respect to skin cancer. We have exposed normal human epidermal keratinocytes to a commercial tanning lamp and used the comet assay in association with DNA repair enzymes T4 endonuclease V and endonuclease III to investigate the relative yields of directly formed cyclobutane pyrimidine dimers (CPDs) and indirectly formed types of oxidative DNA damage. To put the risk of using tanning lamps into perspective, the sunbed used in this study (five Philips Performance 80W-R UVA tubes at a distance of 35 cm) was found to be approximately 0.7 times as potent at inducing CPDs as U.K. natural sunlight around noon on a fine summer day. This compares with a relative risk for CPD induction and erythema of 0.8 and 0.7 times, respectively, calculated from the relevant action spectra of tanning lamps and British noontime sunlight. To determine the relative contribution of UVB and UVA to the induction of CPDs and oxidative DNA damage, we modified the spectral output of the tanning lamps with a series of Schott WG UVB filters. The induction of CPDs was more dependent on the UVB component of the sunbed than oxidative types of damage. Schott WG UVB filters with 50% transmission at 305 nm reduced the yield of T4 endonuclease V sites by 42% while there was only a 17% decrease in the yield of endonuclease III sites. CPD induction was not completely abolished after irradiation through WG335 and WG345 nm filters despite there being no detectable UVB. From these data, it was estimated that, although the tanning lamps emitted only 0.8% of their total output in the UVB range, these wavelengths were responsible for the induction of over 75% of CPDs and 50% of the oxidative damage to DNA.

Possible effects of sunlight on human lymphocytes.

The human population is exposed to both the ultraviolet A (UVA) and B (UVB) regions of the solar spectrum. UVB induces mainly dipyrimidine photoproducts in DNA by a direct photochemical mechanism, whereas UVA is absorbed by other cellular constituents and induces mainly oxidative damage indirectly. The proportions of the different dipyrimidine photoproducts, and the ratio of dipyrimidine to oxidative damage depend on the exact spectral output of a UV source. Irradiation of human epidermal keratinocytes induces release of cytokines, with cyclobutane pyrimidine dimers playing a significant role in the process. These cytokines may then modulate the activity of cells of the immune system. Freshly isolated human lymphocytes are exquisitely sensitive to UVB irradiation, because of their low deoxyribonucleotide pools. They also have a separate defect in removal of cyclobutane pyrimidine dimers from their DNA. We have observed that frequencies of mutations at the hprt locus in human T-lymphocytes and translocations involving the bcl2 locus in B-lymphocytes appear to be associated with sunlight levels over the period before the blood sample was taken. This may be an indirect cytokine-mediated effect, and may be relevant to the possible link between non-Hodgkin's lymphoma and sunlight. On the other hand, sunlight can have beneficial effects, and may protect against autoimmune diseases including type I diabetes and multiple sclerosis.

Induction of interleukin-6 production by ultraviolet radiation in normal human epidermal keratinocytes and in a human keratinocyte cell line is mediated by DNA damage.

The sunburn reaction is the most common consequence of human exposure to ultraviolet radiation (UVR), and is mediated at least in part by interleukin-6 (IL-6). The aim of this study was to determine if DNA is a major chromophore involved in the induction of IL-6 following UV irradiation of a human epidermoid carcinoma cell line (KB), and of normal human epidermal keratinocytes. We first confirmed that IL-6 release was associated with enhanced levels of IL-6 mRNA transcripts. The wavelength dependence for IL-6 release was then investigated by irradiating the cells at defined wavelengths (254, 302, 313, 334, and 365 nm) with a monochromator. The maximum effect on IL-6 release was observed at 254 nm with only low levels of induction observed at wavelengths above 313 nm. The wavelength dependence for UV-induced IL-6 release was similar to that for DNA absorption or for the induction of cyclobutane pyrimidine dimers (CPD). To determine whether UV-induced DNA damage mediated IL-6 secretion, the role of CPD was investigated by treating keratinocytes with photosomes (photolyase encapsulated in liposomes) followed by photoreactivating light. This photoreversal procedure led to a reduction in the levels of the UVC-induced secretion of IL-6, which in normal human keratinocytes was unambiguously associated with repair of CPD. We conclude that the release of IL-6 from human keratinocytes following short-wave UVC and UVB irradiation is mediated by DNA damage and that CPD play an important role in this process.