Cytokine release by peripheral blood mononuclear cells is affected by 8-methoxypsoralen plus UV-A

The effect of phototherapy on systemic inflammatory process in patients with plaque psoriasis

Psoriasis is a common, chronic immune-mediated inflammatory disease. The inflammatory process in psoriasis has systemic effects and may influence the development of psoriatic comorbidities. The systemic action of phototherapy in patients with psoriasis has been so far poorly elucidated. We aimed to investigate the expression of genes encoding selected psoriasis-related cytokines in peripheral blood mononuclear cells (PBMCs) isolated from patients with psoriasis before and after treatment with phototherapy. 17 patients with mild to moderate plaque psoriasis were treated with narrow band-UVB (NB-UVB), 8 patients with moderate to severe plaque psoriasis with bath-psoralen-ultraviolet A therapy (PUVA). PBMCs were isolated by Ficoll gradient density centrifugation. Expression of genes encoding TNF-α, IL-17A, IL-6, IL-1 β, INF-γ, and IL-10 in PBMCs of patients with psoriasis before and after phototherapy was analyzed with quantitative RT-PCR. Treatment with NB-UVB therapy led to a significant decrease in IL-17A, TNF-α, and IL-6 mRNA levels in PBMCs (p=0.003; p=0.042; p=0.019, respectively). Following treatment with bath-PUVA therapy, we observed a significant decrease in TNF-α and IL-6 mRNA levels in PBMCs (p=0.031, p=0.035, respectively). Treatment with phototherapy in patients with psoriasis may affect systemic inflammation by downregulation of the expression of genes encoding proinflammatory cytokines in PBMCs, implicated in the development of psoriasis and psoriatic comorbidities.

Revisited the potential risks of carcinogenicity of phototherapy in patients with psoriasis

The article presents published data on the assessment of the risk of cancerogenicity of multiple courses of phototherapy methods such as PUVA therapy and UVB-311 in psoriatic patients. The authors analyzed the incidence of malignant skin neoplasms (squamous cell carcinoma, basal cell carcinoma, malignant skin melanoma) among psoriatic patients from different population groups taking into account the cumulative radiation doses and number of procedures.

Topical ALA-PDT modifies neutrophils' chemiluminescence, lymphocytes' interleukin-1beta secretion and serum level of transforming growth factor beta1 in patients with nonmelanoma skin malignancies A clinical study

BACKGROUND

Photodynamic therapy (PDT) has been recognized as a noninvasive therapeutic approach for the effective treatment of tumors. It has been shown in studies conducted on malignant cell lines and various animal tumor models, that the interaction of photosensitizing substances with light leads to the release of cytotoxic substances and stimulates the immune response.

PURPOSE

The aim of our study was to analyze the immune system response in patients undergoing photodynamic therapy due to basal cell carcinoma (BCC).

METHODS

Patients with skin malignancies have been treated by 10% delta-aminolevulinic acid (ALA) (Medac GmbH, Wedel, Germany) topically and light from a diode laser. Blood samples were obtained from each patient twice in the same day: before and 4h after photodynamic treatment procedure. In patients' serum the concentration of transforming growth factor beta1 (TGF-β1) was determined. Additionally the study has been conducted on lymphocytes and granulocytes from peripheral blood. In cell culture supernatants the concentration of interleukin 1beta (IL-1β), interleukin 2 (IL-2), interleukin 6 (IL-6), tumor necrosis factor alpha (TNFα), the percentile composition of patients' lymphocytes and the chemiluminescence of neutrophils have been measured.

RESULTS

We have observed a significant increase (p=0.015) in the intensity of the neutrophil chemiluminescence and significant diminution (p=0.006) of IL-1β concentration in supernatants. Similarly the serum level of TGF-β1 has been significantly decreased (p<0.001).

CONCLUSION

It is very likely that human immune system activity is modified by topical ALA-PDT and may potentially contribute to its final outcome.

Narrow-band ultraviolet B phototherapy versus broad-band ultraviolet B or psoralen-ultraviolet A photochemotherapy for psoriasis

BACKGROUND

The most commonly used types of phototherapy for treating psoriasis are narrow-band ultraviolet B (NB-UVB); broad-band ultraviolet B (BB-UVB), which includes selective (delivering radiation with a wavelength range of 305 to 325 nm) and conventional BB-UVB (280 to 320 nm); and psoralen ultraviolet A photochemotherapy (oral or bath PUVA). There is substantial controversy regarding their efficacy when compared with each other.

OBJECTIVES

To assess the effects of narrow-band ultraviolet B phototherapy versus broad-band ultraviolet B or psoralen ultraviolet A photochemotherapy for psoriasis.

SEARCH METHODS

We searched the following databases up to August 2013: the Cochrane Skin Group Specialised Register, CENTRAL in The Cochrane Library (2013, Issue 7), MEDLINE (from 1946), and EMBASE (from 1974). We searched the following databases up to November 2012: CNKI (from 1974) and CBM (from 1978). We also searched trials registers and the OpenGrey database.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) that compared NB-UVB phototherapy with BB-UVB or PUVA for treating psoriasis, which included chronic plaque psoriasis (CPP), guttate psoriasis (GP), and palmoplantar psoriasis (PPP).

DATA COLLECTION AND ANALYSIS

Two review authors independently conducted the study selection, 'Risk of bias' assessment, and data extraction.

MAIN RESULTS

We included 13 RCTs, with a total of 662 participants. We report the results of intention-to-treat analyses (ITT) here. Our primary outcomes of interest were as follows: Participant-rated global improvement, Percentage of participants reaching Psoriasis Area and Severity Index (PASI) 75 (which meant equal to or more than 75% reduction in PASI score), Withdrawal due to side-effects, and Clearance rate.In one RCT of NB-UVB compared with oral PUVA in participants with CPP, the difference in PASI 75 was not statistically significant (risk ratio (RR) 0.91, 95% confidence interval (CI) 0.63 to 1.32; N = 51; low quality). In three other RCTs of CPP, the clearance rates were inconsistent because in one, there was no difference between the groups (RR 1.01, 95% CI 0.91 to 1.12; N = 54), and in the other two, the clearance rates were statistically significantly in favour of oral PUVA: RR 0.66, 95% CI 0.47 to 0.93; N = 93 and RR 0.75, 95% CI 0.59 to 0.96; N = 100, respectively. Pooled data from these three studies indicated that withdrawals due to adverse events were not significantly different between either group (RR 0.71, 95% CI 0.20 to 2.54; N = 247; low quality).The evidence from the comparison of NB-UVB with bath PUVA in terms of clearance rate for CPP was also inconsistent: Pooled data from two left-right body comparison RCTs found no significant difference between the NB-UVB and bath PUVA groups (RR 1.79, 95% CI 0.46 to 6.91; N = 92; low quality), while a parallel RCT favoured bath PUVA (RR 0.18, 95% CI 0.05 to 0.71; N = 36; low quality).In participants with PPP, one RCT found there were no significant differences between NB-UVB treated sides and topical PUVA treated sides in terms of clearance rate (RR 0.09, 95% CI 0.01 to 1.56; N = 50; low quality).Two RCTs found NB-UVB plus retinoid (re-NB-UVB) and PUVA plus retinoid (re-PUVA) had similar effects for treating people with CPP or GP in terms of clearance rate (RR 0.93, 95% CI 0.79 to 1.10; N = 90; low quality).One RCT in people with CPP found no significant differences between NB-UVB and selective BB-UVB in terms of clearance rate (RR 1.40, 95% CI 0.92 to 2.13; N = 100; low quality) and withdrawals due to adverse events (RR 3.00, 95% CI 0.32 to 27.87; N = 100; low quality).No studies reported our primary outcomes for NB-UVB compared with conventional BB-UVB.

AUTHORS' CONCLUSIONS

Current evidence is very heterogeneous and needs to be interpreted with caution. The clearance rate between oral PUVA and NB-UVB is inconsistent among the included studies. Evidence regarding NB-UVB versus bath PUVA is also inconsistent. Re-NB-UVB and re-PUVA are similarly effective for treating people with CPP or GP. In practice, NB-UVB may be more convenient to use since exogenous photosensitiser is not required before phototherapy.NB-UVB is considered ineffective for PPP in clinical practice, and a small RCT did not detect a statistically significant difference between NB-UVB and topical PUVA for clearing PPP. NB-UVB seemed to be similar to selective BB-UVB for clearing CPP.Larger prospective studies are needed to confirm the long-term safety of NB-UVB.

Involvement of IL-17F via the induction of IL-6 in psoriasis

Recently, the important role of T helper 17 (Th17) cells in psoriasis has been clarified; however, the role of IL-17F produced by Th17 cells is still not fully understood. IL-6 exhibits multiple biologic functions, such as regulation of immunological responses including those in psoriatic reactions. Therefore, we examined the production of IL-6 protein in normal human epidermal keratinocytes (NHEKs) stimulated by IL-17F, TNF-alpha, IL-17A, and IL-17A in combination with TNF-alpha, and PBS control. We then examined the expression of IL-6 mRNA in mouse skin after intradermal injection of IL-17F. Finally, IL-17F expression in skin biopsy specimens from psoriasis patients was examined by immunohistochemistry. The results showed that IL-17F induced production of IL-6 in NHEKs in a time-dependent manner. This could be attenuated by chimeric inhibitor blocking the IL-17 receptor. The amounts of IL-6 stimulated by IL-17F were much higher than those stimulated by TNF-alpha or IL-17A. IL-6 was also significantly upregulated via synergistic stimulation with IL-17A plus TNF-alpha. The expression of IL-6 mRNA 24 h after IL-17F injection in the mouse skin was 3.2-fold higher than that in the control group. Immunohistochemistry of inflammatory cells in the dermis demonstrated a large number of CD4(+) T cells showing IL-17F positivity in psoriatic skin lesions, but few or none in non-lesional psoriatic skin. Our results indicate that IL-17F produced by CD4(+) T cells causes the inflammation in psoriasis partly through induction of IL-6 in keratinocytes.

Soluble tumour necrosis factor-α receptor type 1 as a biomarker of response to phototherapy in patients with psoriasis

The purpose of the study was to analyze the relationship between the serum concentration of soluble tumour necrosis factor-alpha type 1 (sTNF-R1), the severity of plaque-type psoriasis and therapeutic response. We compared sTNF-R1 in 25 patients treated with narrowband ultraviolet B (NB-UVB) radiation and 25 patients treated with systemic photochemotherapy (psoralen plus UVA-PUVA). The pretreatment Psoriasis Area and Severity Index (PASI) score and sTNF-R1 concentration were 16.32+/-5.26 and 1.99+/-0.40 ng ml(-1), respectively, in the group treated with NB-UVB, and 17.22+/-3.48 and 2.07+/-0.31 ng ml(-1), respectively, in the group treated with PUVA. The concentration of sTNF-R1 in healthy controls was 1.49+/-0.34 ng ml(-1) (p<0.05 compared with patients with psoriasis). The pretreatment PASI score correlated with sTNF-R1 in both treatment groups (r=0.46 and r=0.44, p<0.05). NB-UVB and PUVA gave similar therapeutic effects (the PASI score after 20 treatments was 4.42+/-1.67 in the NB-UVB-treated group and 5.55+/-2.10 in PUVA-treated patients); however, the sTNF-R1 concentration at the same time differed significantly: 1.52+/-0.37 ng ml(-1) and 1.98+/-0.39 ng ml(-1) (p<0.001), respectively. Moreover, the decline in sTNF-R1 in both treatment groups was significant only in patients in whom the duration of skin lesions was less than 3 months. The results suggest that the value of serum sTNF-R1 concentration as a marker of response to phototherapy may depend on duration of skin lesions and the treatment method.

Extracorporeal photopheresis: A focus on apoptosis and cytokines

Induction of apoptosis and changes to cytokine secretion patterns have been implicated in the mechanism of action of extracorporeal photopheresis (ECP). Lymphocyte apoptosis is initially detected in significant numbers prior to re-infusion and by 48 h post-ECP the majority of treated lymphocytes are apoptotic. The early apoptosis involves changes to mitochondrial function, reversal of the Bcl-2/Bax ratio and externalisation of phosphatidylserine. Apoptotic lymphocytes, observed from 20 h post-ECP, are associated with enhanced levels of CD95 and Fas-ligand. For cutaneous T cell lymphoma (CTCL), processing of the apoptotic lymphocytes, by suitable antigen presenting cells (APCs), is suggested to induce a clonal cytotoxic response which targets the malignant T cell population. Increased levels of TNFalpha and IFNgamma, observed post-ECP in monocytes and lymphocytes, respectively, are thought to further contribute to the proposed anti-tumour reaction seen in CTCL. However, down-regulation of pro-inflammatory cytokines and enhanced anti-inflammatory responses have been reported following ECP treatment. These immune responses may contribute to the tempering of the inflammatory conditions, such as graft versus host disease, which respond to ECP. Furthermore, untreated monocytes exposed to ECP-treated lymphocytes have also demonstrated a shift in monocyte cytokine-secretory pattern, toward one associated with immune tolerance. Recently, a mechanism of ECP-induced immune tolerance has been linked to the stimulation of the anti-inflammatory cytokines IL10 and TGFbeta by T regulatory cells, following the infusion of ECP-treated CD11c(+) APCs. Ultimately, the multifaceted responses, induced by ECP, may explain the diversity of clinical conditions that benefit.

The down-regulation of IL1alpha and IL6, in monocytes exposed to extracorporeal photopheresis (ECP)-treated lymphocytes, is not dependent on lymphocyte phosphatidylserine externalization

Extracorporeal photopheresis (ECP) has been successfully used to treat some inflammatory conditions. Following ECP, lymphocytes become apoptotic and untreated monocytes, exposed to post-ECP lymphocytes, reduce proinflammatory cytokine secretion. This study attempted to establish if this monocyte immunosuppression was linked to phosphatidylserine externalization (detected using Annexin V) on the apoptotic lymphocytes. Using density gradient and magnetic separation, lymphocytes were isolated from three cutaneous T-cell lymphoma and nine chronic graft versus host disease (cGvHD) patients pre-ECP and prior to re-infusion (post-ECP). The collected lymphocytes were cultured overnight and Annexin V levels determined. Peripheral blood was taken from the same patient 20 h later and the monocytes were isolated. The 'fresh' monocytes were introduced to each 20 h pre- and post-ECP lymphocyte culture, stimulated with lipopolysaccharide (LPS) and Brefeldin A and subsequently tested for intracellular tumour necrosis factor alpha, interleukin 1 alpha (IL1alpha), IL1beta, IL6 and IL8. For cGvHD patients, the relative levels of IL1alpha and IL6 were reduced in the untreated, LPS-stimulated monocytes exposed to post-ECP lymphocytes. However, the down-regulation of IL1alpha and IL6 did not correlate to levels of Annexin V-positive lymphocytes. ECP-treated lymphocytes can reduce the ability of LPS-stimulated monocytes to produce some proinflammatory cytokines; however, this effect is not dependent on phosphatidylserine externalization.

Lymphocytes treated by extracorporeal photopheresis can down-regulate cytokine production in untreated monocytes

BACKGROUND

Pro-inflammatory cytokines are actively involved in graft-versus host-disease (GvHD) aetiology. Treatment of GvHD, using extracorporeal photopheresis (ECP), has demonstrated clinical efficacy. ECP rapidly reduces the number of T cells that produce tumour necrosis factor alpha (TNFalpha), interferon gamma (IFNgamma) and interleukin (IL)2. ECP-treated cells are re-infused immediately after completion of treatment. This study attempted to determine the influence that ECP-treated cells would have on untreated cells following re-infusion.

METHODS

Heparinized samples were taken from 10 chronic GvHD patients, pre-ECP and immediately prior to re-infusion (post-ECP). Lymphocytes and monocytes were isolated using magnetic separation. The post-ECP lymphocytes were mixed with pre-ECP monocytes, while the post-ECP monocytes and pre-ECP lymphocytes were combined. After suitable stimulation, the T cells were tested for intracellular TNFalpha, IFNgamma and IL2, while the monocytes were evaluated for TNFalpha, IL1alpha, IL1beta, IL6 and IL8.

RESULTS

Although cytokine secretion is decreased in T cells exposed to ECP, pre-ECP T cells were unaffected by post-ECP monocytes. Post-ECP monocytes demonstrated a reduction in cytokine secretion. Furthermore, untreated monocytes down-regulated cytokine production following exposure to ECP-treated lymphocytes.

CONCLUSION

ECP has both a direct and indirect immunosuppressive action, both of which may be beneficial in the treatment of GvHD.

Behavioral and biochemical studies of total furocoumarins from seeds of Psoralea corylifolia in the forced swimming test in mice

The behavioral and biochemical effects of total furocoumarins from seeds of Psoralea corylifolia (TFPC) were investigated in the forced swimming test (FST) in mice in comparison with amitriptyline and fluoxetine. TFPC was found to reduce the duration of immobility in the FST without accompanying changes in ambulatory, rearing and grooming behaviors in the open-field test. After a 3-day treatment, TFPC at the doses from 7.5 to 100 mg/kg significantly decreased the immobility time. The efficacy of the higher doses exceeded that of amitriptyline at 10 and 20 mg/kg and fluoxetine at 13 mg/kg. After a 7- or 14-day treatment, TFPC exhibited an inverted U-shaped dose-response relations, maximal effects were obtained at 30 mg/kg, when the efficacy appeared to be more than that of amitriptyline and fluoxetine. In animal brain and liver, after 14-day treatment, TFPC significantly inhibited monoamine oxidase A and B (MAO-A and MAO-B) activities with an inverted U-shaped dose-dependent relationship in brain, and with dose-dependent relationship in liver. Moreover, TFPC was more potent for MAO-B than MAO-A, except at the lowest dose, which was similar to amitriptyline and fluoxetine. In addition, TFPC blocked plasma elevated cortisol level, an indicator of the hypothalamic-pituitary-adrenal (HPA) axis. TFPC significantly decreased liver superoxide dismutase (SOD) activity and malondialdehyde (MDA) level, two indicators of oxidative stress, providing an inverted U-shaped dose-dependent relationship. These results suggest that TEPC possesses potent antidepressant properties that are mediated via MAO activity, HPA axis action and oxidative stress in the FST in mice.

Extracorporeal Photopheresis Differentially Regulates the Expression of Phosphorylated STAT-1 and STAT-5 in Treated Monocytes and T cells, Respectively

BACKGROUND

Extracorporeal photopheresis (ECP) is effective in conditions with opposing immune etiology. ECP induces an immunomodulatory response through simultaneous monocyte activation and apoptosis induction of lymphocytes. However, ECP is also immunosuppressive, downregulating proinflammatory cytokines. Signal transducers and activators of transcription (STATs) are important mediators of cell-signaling systems, including cytokines. Ultraviolet (UV) immunosuppression is linked to reductions in cytokine-induced STAT phosphorylation.

OBJECTIVE

The aim of this study was to find whether ECP downregulates STAT phosphorylation.

METHODS

Pre- and post-ECP mononuclear cells from cutaneous T-cell lymphoma and chronic graft-versus-host disease patients were stimulated with either IFNbeta, IL2, or IL15. The percentage of IFNbeta-stimulated monocytes positive for phosphorylated STAT-1 (pSTAT-1) and the number of IL2- and IL15-stimulated T cells expressing phosphorylated STAT-5 (pSTAT-5) were determined at 0 and 24 h.

RESULTS

Post-ECP, pSTAT-1 levels in monocytes remained unchanged; however, at 24 h post-ECP the number of T cells expressing pSTAT-5 was reduced.

CONCLUSION

Following ECP, monocytes retain their ability to phosphorylate STAT-1, while pSTAT-5 expression is lost in lymphocytes. This differential effect of ECP may account for the diverse population of diseases that benefit.

Oral PUVA and topical steroids for treatment of oral manifestations of chronic graft-vs.-host disease

BACKGROUND

Oral manifestations of chronic graft-vs.-host disease (cGVHD) can significantly affect the quality of life and severity often does not correlate with systemic manifestations. We evaluated the use of topical corticosteroids and the intraoral application of psoralen-UVA (PUVA) for treatment of oral manifestations of cGVHD.

METHODS

Overall, 18 patients with oral manifestations of cGVHD were treated with either intraoral PUVA (n=7) or with topical corticosteroids (n=16). Four patients received intraoral PUVA after failure of topical steroids and one patient was treated with topical corticosteroids after failing treatment with intraoral PUVA. A glass fiber extension of an UVA source was used for manual intraoral application. Treatment with topical corticosteroids consisted of 0.1 mg/ml dexamethasone mouth wash four times a day in combination with antifungal prophylaxis.

RESULTS

Four patients showed complete local response (CR) due to intraoral PUVA, two improved and one did not respond. Topical corticosteroids resulted in nine patients in CR, two improved and five did not respond.

CONCLUSION

Intraoral PUVA as well as topical corticosteroids are effective in treatment of oral manifestations of oral GVHD with few side-effects and improve quality of life in patients with cGVHD.

Toxic effects of ultraviolet radiation on the skin

Ultraviolet (UV) irradiation present in sunlight is an environmental human carcinogen. The toxic effects of UV from natural sunlight and therapeutic artificial lamps are a major concern for human health. The major acute effects of UV irradiation on normal human skin comprise sunburn inflammation (erythema), tanning, and local or systemic immunosuppression. At the molecular level, UV irradiation causes DNA damage such as cyclobutane pyrimidine dimers and (6-4) photoproducts, which are usually repaired by nucleotide excision repair (NER). Chronic exposure to UV irradiation leads to photoaging, immunosuppression, and ultimately photocarcinogenesis. Photocarcinogenesis involves the accumulation of genetic changes, as well as immune system modulation, and ultimately leads to the development of skin cancers. In the clinic, artificial lamps emitting UVB (280-320 nm) and UVA (320-400 nm) radiation in combination with chemical drugs are used in the therapy of many skin diseases including psoriasis and vitiligo. Although such therapy is beneficial, it is accompanied with undesirable side effects. Thus, UV radiation is like two sides of the same coin--on one side, it has detrimental effects, and on the other side, it has beneficial effects.

UVA activated 8-MOP and chlorpromazine inhibit release of TNF-α by post-transcriptional regulation

There is evidence that regulation of inflammatory cytokines is among the immunomodulatory effects of photochemotherapy with 8-MOP and UVA. We have recently demonstrated that in the monocytoid cell line U937 incubation with 8-MOP and subsequent exposure to UVA is able to efficiently downregulate the release of TNF-alpha into the culture supernatant. Chlorpromazine, a well known photosensitising drug, was even more potent with regard to this effect. Based on these observations, in this study we further investigate the mechanisms of TNF-alpha inhibition by 8-MOP and CPZ photosensitization. For this purpose we determined intracellular protein levels and gene expression of TNF-alpha by western blot and quantitative real-time PCR, respectively. Our results indicate that the observed inhibition of TNF-alpha secretion after photochemotherapy is not due to downregulation of gene transcription but rather to a post-transcriptional mechanism. The observed decrease of intracellular TNF-alpha with CPZ and 8-MOP points to decreased protein synthesis or enhanced degradation. These findings demonstrate that posttranscriptional regulation of cytokine expression is a possible mechanism of action of photochemotherapy.

Extracorporeal photopheresis reduces the number of mononuclear cells that produce pro-inflammatory cytokines, when tested ex-vivo

Extracorporeal photopheresis (ECP) has been shown to be clinically effective in the treatment of many T cell-mediated conditions. ECP's mechanism of action includes the induction of apoptosis and the release of pro-inflammatory cytokines. Recently, we have observed early lymphoid apoptosis, detectable immediately post ECP. We were interested to determine what influence ECP has on pro-inflammatory cytokine secretion at this early pre-infusion stage. Samples from 6 cutaneous T cell lymphoma (CTCL) and 5 graft versus host disease (GvHD) patients were taken pre ECP and immediately post ECP, prior to re-infusion. Following separation, the PBMCs were added to a cell culture medium and stimulated with PMA, Ionomycin, and Brefeldin A for 6 hours. Using flow cytometry, intracellular cytokine expression of IFNgamma and TNFalpha was determined in the T cell population. The monocytes were evaluated for IL6, IFNgamma, IL12, and TNFalpha. For both patient groups, the number of IFNgamma-expressing T cells fell significantly at re-infusion, whilst both T cell- and monocyte-expressing TNFalpha levels were reduced at re-infusion. All other cytokines tested showed no significant change post ECP. For GvHD, pro-inflammatory cytokines have a pathological role. Their down-regulation may have a direct clinical benefit. However, the reduction in the number of IFNgamma- and TNFalpha-expressing mononuclear cells means, at this early stage, it is unlikely that these cytokines assist in the removal of the malignant Th2 cells present in CTCL.

Augmentation of monocyte interleukin-8 production by psoralen/UVA-treated CD4+ T cells

Treatment of cells with psoralen and ultraviolet A light (UVA) modulates their cytokine production. As extracorporeal photochemotherapy has been reported to induce cytokine production by monocytes, we quantified interleukin-8 (IL-8), a representative chemokine produced by monocytes, in culture supernatants from human peripheral blood mononuclear cells (PBMC) treated with 8-methoxypsoralen (8-MOP) and UVA. Lipopolysaccharide stimulated IL-8 production in 8-MOP-phototreated PBMC more efficiently than those untreated or treated with 8-MOP or UVA. More interestingly, when cultured with T-cell-stimulating anti-CD3 and anti-CD28 antibodies, 8-MOP/UVA-treated PBMC produced enhanced amounts of IL-8 with an increased level of IL-8 mRNA expression. Depletion of CD4 but not CD8 T cells from PBMC abrogated this augmented IL-8 elaboration, and CD4 T cells per se secreted no substantial amount of IL-8 even upon CD3/CD28 stimulation. Thus, 8-MOP/UVA-treated CD4 T cells stimulated monocytes to secrete IL-8. The IL-8 overproduction was induced by direct contact of monocytes with 8-MOP/UVA-treated CD4 T cells but not by cytokines from the treated CD4 T cells. These findings imply that in extracorporeal photochemotherapy, monocytes effectively produce IL-8 by cell-to-cell contact with 8-MOP/UVA-treated malignant CD4 T cells. The augmentation of monocyte cytokine/chemokine production by 8-MOP/UVA may be one of the mechanisms underlying the therapeutic efficacy of extracorporeal photochemotherapy.

Role of immunomodulation in diseases responsive to phototherapy

Within the last two decades phototherapy has turned out to be a major therapeutic strategy in dermatology and thus has significantly influenced the treatment of many dermatoses. The goals of therapeutic photomedicine are the suppression of ongoing disease processes and, more importantly, the prevention, modulation, or abrogation of pathogenic mechanisms causing the disease. Therapeutic photomedicine has been largely empirical and most of it is still empirical today. However, parts of it are already based on the advances in photoimmunology and molecular biology. Although, we are far from a detailed understanding of the mechanisms underlying phototherapy, there is increasing evidence that phototherapy acts via modulation of the immune system. Most of the effects of both ambient and therapeutic ultraviolet radiation are immunosuppressive in nature.

PUVA downregulates whn expression in primary mouse keratinocytes

Psoralen photochemotherapy (PUVA) is one of the most efficient treatment regimens for psoriasis and other skin diseases. In order to evaluate keratinocyte-specific PUVA effects, we investigated the impact of clinically relevant PUVA doses on whn, the 'nude' gene. This transcription factor plays an important role in epidermal homeostasis, and epidermal whn over-expression results in a psoriasis-like phenotype. We demonstrated a persistent down-regulation of whn mRNA 48-72 h after PUVA treatment but not after UVA alone. Using transgenic animals, we also demonstrated dose-dependent down-regulation of whn promoter activity. Finally, whn-null ('nude') keratinocytes were more resistant to PUVA-induced suppression of DNA synthesis than wild-type cells. Our results suggest that whn suppression may be involved in mediating the anti-proliferative effect of PUVA on keratinocytes.

Photoactivational cytokine-modulatory action of 8-methoxypsoralen plus ultraviolet A in lymphocytes, monocytes, and cutaneous T cell lymphoma cells

Treatment with 8-methoxypsoralen (8-MOP) and ultraviolet A light (UVA) has been reported to modulate cytokine production in various cells. Our study was conducted to see the effects of 8-MOP/UVA on the expression/production of cytokines in peripheral blood lymphocytes and monocytes in relation to the therapeutic mechanisms of extracorporeal photochemotherapy. 8-MOP/UVA augmented the expression of mRNAs for interferon-gamma (IFN-gamma) and interleukin (IL)-2 and reduced those for IL-4 and IL-10 in peripheral blood mononuclear cells (PBMCs) from normal subjects and Sézary syndrome patients. This enhancement of Th1 cytokines was caused by increment of cytokine production by Th1 cells but not by conversion of Th2 cells to produce Th1 cytokines. The number of IFN-gamma-secreting lymphocytes was markedly increased in 8-MOP/UVA-treated PBMCs 20 h after treatment, and its amount was elevated in culture supernatants. However, this enhanced production of IFN-gamma was found only until three days after 8-MOP phototreatment, and its level was rapidly declined by five days after treatment. In addition to this Th1-polarized action, 8-MOP/UVA-treated PBMCs produced enhanced amounts of IL-8 upon stimulation with anti-CD3/CD28 antibodies. Phototreated CD4+ but not CD8+ cells provided excellent T cell help for monocytes to produce IL-8 via a direct cell-to-cell contact mechanism. These findings suggest that 8-MOP/UVA has a transient but biologically active Th1-skewing action in T cells, and the phototreated T cells simultaneously stimulate monocytes to produce IL-8. It is suggested that 8-MOP/UVA exerts a beneficial therapeutic effect on malignant Th2 neoplasms as a Th1-skewing cytokine modifier and that 8-MOP-phototreated CD4+ T cells allow monocytes to become effective tumor antigen-presenting cells for tumor-specific cytotoxic T cells.

PUVA (psoralen + UVA) photochemotherapy: processes triggered in the cells

Photochemotherapy using psoralens and UVA is a treatment used widely in some skin diseases, in cutaneous lymphomas and in autoimmune diseases. This review has selected recent publications dealing with the photochemical processes triggered in the cells by UVA radiation and psoralen treatment. The photochemical changes initiated in the cell membranes were described.

Ultraviolet B radiation exerts enhancing effects on the production of a complement component, C3, by interferon-gamma-stimulated cultured human epidermal keratinocytes, in contrast to photochemotherapy and ultraviolet A radiation that show suppressive effects

The present study was designed to investigate by using enzyme-linked immunosorbent assay and reverse transcriptase-polymerase chain reaction methods whether photochemotherapy (PUVA) or ultraviolet (UV) B treatment affects C3 production by interferon (IFN)-gamma-stimulated keratinocytes cultured in serum-free medium. The results showed that PUVA and UVA reduced C3 production by IFN-gamma-stimulated epidermal keratinocytes dose-dependently, although the effect of PUVA was stronger than that of UVA alone. Interestingly, UVB induced an enhancement of C3 production at doses ranging from 10 to 50 mJ cm-2. This phenomenon was found at both the protein and mRNA levels. In every experiment, changes in C3 mRNA levels preceded those in its protein levels. Reduced C3 production at higher doses of 75 and 100 mJ cm-2 were probably due to cytotoxic effects of UVB. In our experimental system, PUVA, UVA or UVB treatment did not affect C3 production without IFN-gamma stimulation. Our results suggest that a reduction in C3 production by PUVA treatment may in part explain the efficacy of PUVA in the treatment of inflammatory dermatoses such as psoriasis, while the results of the UVB experiments may partially explain the proinflammatory nature of UVB.

Management of graft-versus-host disease in paediatric bone marrow transplant recipients

We discuss clinical strategies for the prophylaxis and treatment of both acute and chronic graft-versus-host disease (GVHD) with particular attention to children. Grades II to IV acute GVHD occur in 10 to 50% of patients given an allogeneic transplantation of haemopoietic stem cells (HSCT) from a genotypically HLA-identical donor. A significantly higher incidence and severity of the disease is reported in patients receiving transplants from partially matched family donors or unrelated volunteers. Younger individuals or patients receiving HSCT from younger donors develop GVHD less frequently than do older recipients. Severe acute GVHD is characterised by a significant decrease in survival probability, even though the graft-versus-leukaemia activity associated with both acute and chronic GVHD may reduce the risk of leukaemia relapse. Prophylaxis of acute GVHD usually consists of in vivo post-grafting immunosuppression with cyclosporin alone or in combination with methotrexate; methotrexate alone can be considered in leukaemia patients with a high risk of relapse. In recent years, tacrolimus is increasingly being used instead of cyclosporin, alone or in combination with methotrexate. In vitro T cell depletion in paediatric patients is usually reserved for those with transplants from partially matched family donors or unrelated volunteers. The treatment of patients with grades II to IV acute GVHD should be immediate and aggressive, as the quality and duration of the response directly correlates with survival. The overall response rate to treatment is often unsatisfactory, ranging from 40 to 50% of cases. First-line treatment usually consists of corticosteroids. In patients not responding to corticosteroids, antilymphocyte globulin and monoclonal antibodies directed towards lymphocytes and/or cytokines produced during GVHD are employed, but with variable success. Patients experiencing acute GVHD are also prone to develop chronic GVHD. whose classical treatment is based on the use of cyclosporin and corticosteroids. More recently, encouraging results in the treatment of patients with chronic GVHD have been reported with the use of extracorporeal photochemotherapy. Other drugs, such as ursodeoxycholic acid, etretinate and clofazimine, are under evaluation.

Ultraviolet B irradiation: a new therapeutic concept for the management of oral manifestations of graft-versus-host disease

Ultraviolet irradiation inhibits the proliferative responses of lymphoid cells to mitogens and alloantigens by inactivation of T lymphocytes and antigen-presenting cells. Its immunosuppressive capacity led to the introduction of UV irradiation into clinical practice for the treatment of dermatologic manifestations of chronic graft-versus-host disease. The cumulative experience with psoralen-UV-A rays in the treatment of cutaneous and oral graft-versus-host disease was the incentive for the application of oral UV-B rays in 2 patients with oral graft-versus-host disease signs and symptoms after allogeneic marrow transplantation. Intraoral UV-B irradiation (0.02 mJ/cm(2)) was administered 2 or 3 times per week on an ambulatory basis; the dose was increased by 0. 02 mJ/cm(2) every fourth session. Both patients responded early and satisfactorily, displaying only minimal side effects at a relatively low cumulative dose. Intraoral UV-B proved a valuable modality in the treatment of resistant chronic oral graft-versus-host disease.

Overexpression of monocyte-derived cytokines in active psoriasis: a relation to coexistent arthropathy

An overexpression of inflammatory cytokines has been found in the lesional skin as well as peripheral blood in patients with psoriasis, although its etiological significance is not yet understood. In order to evaluate the cell type responsible for the elevated cytokines in the peripheral blood, we investigated cytokine profiles of the fractionated peripheral blood mononuclear cells (PBMCs) in 30 patients with psoriasis and 27 healthy controls. Without stimulation, higher levels of interleukin (IL)-1beta, IL-6, and IL-8 were produced by freshly isolated PBMCs from the patients than those from the controls. In the fractionated PBMCs, the monocyte-rich fractions were mainly responsible for the production of these cytokines and mRNA. The elevated levels of monocyte-derived cytokine mRNAs decreased following successful treatment with cyclosporin A. Although no correlation was found between the cytokine levels and the psoriasis area and severity index (PASI) scores, patients with arthropathy showed significantly high production levels of IL-1beta, IL-6, and IL-8. These findings suggest that monocytes are the major cell source producing inflammatory cytokines in the peripheral blood of psoriasis, and the increased cytokine levels are related to the coexistent arthropathy rather than the severity of cutaneous lesions.

Treatment of T lymphocytes with 8-methoxypsoralen plus ultraviolet A induces transient but biologically active Th1-skewing cytokine production

8-Methoxypsoralen plus ultraviolet A light is suggested to shift T lymphocytes from Th2 to Th1 cells. To clarify this issue, we examined the effects of 8-methoxypsoralen/ultraviolet A on the expression/production of cytokines in peripheral blood mononuclear cells from normal subjects and a Sézary syndrome patient. 8-Methoxypsoralen/ultraviolet A augmented the expression of mRNAs for interferon-gamma and interleukin-2 and reduced those for interleukin-4 and interleukin-10. It seems that this enhancement of Th1 cytokines is caused by increment of cytokine production by Th1 cells but not by conversion of Th2 cells to produce Th1 cytokines. The number of interferon-gamma-secreting lymphocytes was markedly increased in 8-methoxypsoralen/ultraviolet A-treated peripheral blood mononuclear cells 20 h after treatment, whereas that of Th2 cytokine-producing cells was decreased. Accordingly, the amount of interferon-gamma was elevated in culture supernatants from 8-methoxypsoralen-phototreated peripheral blood mononuclear cells, whereas interleukin-4 was significantly reduced. This enhanced production of interferon-gamma, however, was found only until 3 d after 8-methoxypsoralen phototreatment and was declined by 5 d after treatment. Finally, 8-methoxypsoralen/ultraviolet A treatment of T cells regulated their ability to induce keratinocyte CD54 expression. Our results show that 8-methoxypsoralen/ultraviolet A has a transient but biologically active Th1-skewing action in human T cells, suggesting that 8-methoxypsoralen/ultraviolet A exerts a beneficial therapeutic effect on Th2-mediated or Th2-malignant diseases.

Elimination of cytokine production in stored platelet concentrate aliquots by photochemical treatment with psoralen plus ultraviolet A light

BACKGROUND

Cytokines generated in platelet concentrates (PCs) during storage have been implicated as possible mediators of febrile nonhemolytic transfusion reactions. Two potential methods of white cell inactivation were compared for their ability to reduce cytokine synthesis in pooled random-donor PC aliquots: treatment with gamma-radiation and photochemical treatment (PCT) using psoralens and ultraviolet A light.

STUDY DESIGN AND METHODS

ABO-matched PC aliquots were pooled and divided into separate aliquots. Aliquots (20 mL) were taken from each pool to serve as an untreated control and to undergo gamma-radiation. Aliquots were treated by using either gamma-radiation (2500 or 5000 cGy) or virucidal PCT. PCT with the psoralens 8-methoxypsoralen (8-MOP), aminomethyltrimethyl psoralen (AMT), and S-59 was investigated. PC aliquots were stored for 7 days and analyzed for levels of interleukin 8 by use of an enzyme-linked immunosorbent assay. Levels of DNA adduct formation were determined by using 3H-labeled psoralens.

RESULTS

Levels of interleukin 8 in the untreated random-donor PC aliquots increased with increasing white cell counts, but they were not affected by pooling. The untreated control aliquots and the aliquots treated with gamma-radiation had significant increases in levels of interleukin 8 after 5 to 7 days of storage (p<0.05). PCT with S-59 resulted in a significant reduction in cytokine synthesis (p<0.05). Day 5 to 7 levels of interleukin 8 did not differ significantly from Day 0 levels. Inhibition of interleukin 8 production by PCT increased with increasing levels of DNA modification (S-59 > AMT > 8-MOP).

CONCLUSION

PCT that utilizes S-59 has been developed to inactivate potential viral and bacterial pathogens in PC aliquots while maintaining in vitro platelet function. These data demonstrate that PCT of aliquots of pooled PC aliquots before storage also prevents white cell cytokine synthesis during storage. PCT may therefore offer the potential for reducing cytokine-associated febrile nonhemolytic transfusion reactions.

Modulation of cytokine production by 8-methoxypsoralen and UVA

Modulatory effects on cytokine expression of 8-MOP in conjunction with UVA have been investigated in different systems using different cell types, including keratinocytes, lymphocytes, monocytes and endothelial cells. The vast majority of data have exhibited reduced production of cytokines in 8-MOP/UVA-treated cells and skin, reflecting its simplistic cellular damage. However, 8-MOP/UVA at modest doses stimulate T lymphocytes to produce Thl cytokines such as interferon-gamma, suggesting that some activational events may occur in certain types of cells phototreated with 8-MOP. Both the inhibitory and augmentative effects of 8-MOP/UVA on cytokine production appear to participate in the mechanisms underlying the therapeutic efficacy of PUVA and extracorporeal photochemotherapy (photopheresis). In particular, photopheresis may exert beneficial effects on cutaneous T-cell lymphoma as a cytokine modifier.

PUVA therapy: current concerns in Japan

Photochemotherapy using methoxsalen in combination with long-wave ultraviolet light (PUVA) is an essential modality in the treatment of various skin diseases. Major therapeutic regimens include oral, topical and water-delivery methods. An adequate regimen should be chosen regarding cases of disease, extent of involvement and the age of patients. In Japan, however, treatment techniques and protocols have not yet been standardized. PUVA therapy may be a first choice in the early stages of mycosis fungoides and a second choice or an adjunctive measure in other diseases, such as psoriasis, vitiligo and atopic dermatitis, which have been disabling or resistant to conventional treatments. Japanese guidelines for PUVA therapy of psoriasis are being prepared to be produced. Risks and benefits must be weighed and the patient orientation is necessary to complete the treatment and also to minimize side-effects. Although possible risks for skin cancers in Japanese patients have been reported to be much lower, a careful monitoring of the patient's skin changes is recommended. While action mechanisms are not completely understood, recent investigations suggest that both antiproliferative and immunomodulatory effects are involved. This review article deals with the recent progress in clinical and basic research on PUVA therapy, focusing on our current concerns.

PUVA inhibits DNA replication, but not gene transcription at nonlethal dosages

The combination of psoralens and UVA radiation (PUVA photochemotherapy) is an established treatment for many skin disorders. UVA-induced psoralen-DNA interactions are assumed to contribute to the cutaneous anti-inflammatory and anti-proliferative effects of PUVA. PUVA-induced DNA modifications might interfere not only with DNA replication, but also with gene transcription of proinflammatory genes. We therefore studied the effect of PUVA on cell proliferation and on the transcription of the c-jun and intercellular adhesion molecule-1 genes in a promyelocytic (HL60) and a keratinocyte (HaCaT) cell line. PUVA inhibited cell proliferation increasingly with increasing 8-methoxypsoralen concentrations or UVA doses. The inhibition was observed at conditions not affecting cell viability up to 48 h after PUVA. In contrast, PUVA did not inhibit gene transcription at anti-proliferative, yet nonlethal conditions. Baseline and phorbol-ester induced c-jun mRNA expression was not inhibited, nor was baseline and IFN-gamma or phorbol-ester induced intercellular adhesion molecule-1 mRNA expression. In order to assess possible transcriptional effects of PUVA-generated reactive oxygen intermediates, the reactive oxygen intermediates-sensitive transcription factor nuclear factor kappaB was assayed in mobility shift experiments. Nuclear factor kappaB-specific binding activity was not induced 1-24 h after PUVA in extracts from PUVA-treated cells when compared with controls, whereas the pro-oxidant cytokine TNF-alpha caused a marked increase in nuclear factor kappaB binding. The presented data suggest that PUVA inhibits cell proliferation, but not transcription, at nonlethal PUVA conditions. Furthermore, the data do not support a major role for PUVA-generated reactive oxygen intermediates in the regulation of gene transcription.

Inactivation of Leukocytes in Platelet Concentrates by Photochemical Treatment With Psoralen Plus UVA

A photochemical treatment (PCT) process using a novel psoralen and long wavelength ultraviolet light (UVA, 320-400 nm) has been developed to inactivate bacteria and viruses in platelet concentrates. This study evaluated the efficacy of PCT for inactivation of leukocytes that contaminate platelet preparations. Three psoralens, 8-methoxypsoralen (8-MOP), 4′-aminomethyl 4,5′,8-trimethylpsoralen (AMT), and the novel psoralen S-59, were compared using the following four independent but complementary biological and molecular assays. (1) T-cell viability: Treatment with 150 μmol/L S-59 and 1.0 to 3.0 Joules/cm2 UVA inactivated >5.4 ± 0.3 log10 of T cells in full-sized single-donor plateletpheresis units. Using 1.0 Joule/cm2 UVA, the lowest dose of S-59, AMT and 8-MOP required to reduce the number of T cells to the limit of detection was 0.05 μmol/L, 1.0 μmol/L, and 10.0 μmol/L, respectively. (2) Cytokine synthesis: Treatment with 1.9 Joules/cm2 UVA and 150 μmol/L S-59 or AMT completely inhibited synthesis of the cytokine IL-8 by contaminating leukocytes during 5 days of platelet storage. After treatment with 75 μmol/L 8-MOP and 1.9 Joules/cm2 UVA, only low levels of IL-8 were detected. (3) Psoralen-DNA adduct formation: The combination of 1.9 Joules/cm2 UVA and 150 μmol/L S-59, AMT, or 8-MOP induced 12.0 ± 3.0, 6.0 ± 0.9, and 0.7 psoralen adducts per 1,000 bp DNA, respectively. (4) Replication competence: Polymerase chain reaction (PCR) amplification of small genomic DNA sequences (242-439 bp) after PCT was inhibited. The degree of PCR amplification inhibition correlated with the level of adduct formation (S-59 > AMT > 8-MOP). In contrast, 2,500 cGy gamma radiation, a dose that inactivates >5 log10 of T cells in blood products, had minimal effect on cytokine synthesis and did not induce sufficient DNA strand breaks to inhibit PCR amplification of the same small DNA sequences. These results demonstrate that leukocytes are sensitive to PCT with psoralens and among the psoralens tested S-59 is the most effective. Therefore, PCT has the potential to reduce the incidence of leukocyte-mediated adverse immune reactions associated with platelet transfusion.

Inactivation of Leukocytes in Platelet Concentrates by Photochemical Treatment With Psoralen Plus UVA

A photochemical treatment (PCT) process using a novel psoralen and long wavelength ultraviolet light (UVA, 320-400 nm) has been developed to inactivate bacteria and viruses in platelet concentrates. This study evaluated the efficacy of PCT for inactivation of leukocytes that contaminate platelet preparations. Three psoralens, 8-methoxypsoralen (8-MOP), 4′-aminomethyl 4,5′,8-trimethylpsoralen (AMT), and the novel psoralen S-59, were compared using the following four independent but complementary biological and molecular assays. (1) T-cell viability: Treatment with 150 μmol/L S-59 and 1.0 to 3.0 Joules/cm2 UVA inactivated >5.4 ± 0.3 log10 of T cells in full-sized single-donor plateletpheresis units. Using 1.0 Joule/cm2 UVA, the lowest dose of S-59, AMT and 8-MOP required to reduce the number of T cells to the limit of detection was 0.05 μmol/L, 1.0 μmol/L, and 10.0 μmol/L, respectively. (2) Cytokine synthesis: Treatment with 1.9 Joules/cm2 UVA and 150 μmol/L S-59 or AMT completely inhibited synthesis of the cytokine IL-8 by contaminating leukocytes during 5 days of platelet storage. After treatment with 75 μmol/L 8-MOP and 1.9 Joules/cm2 UVA, only low levels of IL-8 were detected. (3) Psoralen-DNA adduct formation: The combination of 1.9 Joules/cm2 UVA and 150 μmol/L S-59, AMT, or 8-MOP induced 12.0 ± 3.0, 6.0 ± 0.9, and 0.7 psoralen adducts per 1,000 bp DNA, respectively. (4) Replication competence: Polymerase chain reaction (PCR) amplification of small genomic DNA sequences (242-439 bp) after PCT was inhibited. The degree of PCR amplification inhibition correlated with the level of adduct formation (S-59 > AMT > 8-MOP). In contrast, 2,500 cGy gamma radiation, a dose that inactivates >5 log10 of T cells in blood products, had minimal effect on cytokine synthesis and did not induce sufficient DNA strand breaks to inhibit PCR amplification of the same small DNA sequences. These results demonstrate that leukocytes are sensitive to PCT with psoralens and among the psoralens tested S-59 is the most effective. Therefore, PCT has the potential to reduce the incidence of leukocyte-mediated adverse immune reactions associated with platelet transfusion.

Comparative studies on the tolerance to photoinduced cutaneous inflammatory reactions by psoralen and rose bengal

The photochemotherapeutic value of topical 8-methoxypsoralen (8-MOP) plus UVA irradiation has been well recognized. The phototoxicity associated with psoralen plus UVA (PUVA) therapy is hallmarked by an increase in vascular permeability (iVP), the accumulation of polymorphonuclear leukocytes (aPMN) and erythema formation in situ. Rose bengal (RB) plus UVA-VIS light (320-700 nm) produces a similar acute inflammatory response, but without immediate or delayed erythema and perceptible edema. This study describes some of the parameters involved in inflammatory reactions evoked by PUVA and the results are compared with RB-induced phototoxic reactions. The rates of iVP and aPMN with a 3 h pulse were quantified using 125I-albumin and 51Cr-labelled PMNs respectively. The erythemal response was graded visually. 8-MOP cream was applied topically, while RB was injected intradermally in rabbit skin before UVA-VIS (9.4 J cm-2) irradiation. The data show that there is no significant difference in the rates of iVP, aPMN and erythema formation between normal skin sites and mast cell-depleted skin sites when challenged with 8-MOP plus light. These results suggest that in situ mast cells do not play a significant role in 8-MOP-photoinduced acute cutaneous inflammatory reactions, in contrast with RB-photoinduced reactions. The iVP and aPMN responses are minimal or absent in sites subjected to repeated exposure to 8-MOP plus light for three or more consecutive days, suggesting the establishment of a desensitized/unresponsive state. Moreover, 8-MOP-photo-desensitized sites do not produce iVP and aPMN of the same magnitude as the normal (naive) skin sites when challenged with RB plus light. Similarly, RB-photo-desensitized sites do not produce iVP and aPMN of the same magnitude as the native skin sites when challenged with 8-MOP plus light. The desensitization and cross-desensitization of skin sites to 8-MOP- or RB-photoinduced reactions suggest that there is either direct attack on the target cell(s), thereby removing the ability to express adhesion molecules, such as endothelial leukocyte adhesion molecule 1 (ELAM-1) or intercellular adhesion molecule 1 (ICAM-1), involved in the accumulation of inflammatory cells, or downregulation of the secretion/release of putative agent(s), such as interleukin 1 (IL-1) and tumor necrosis factor alpha (TNF-alpha), responsible for the initiation and progression of cutaneous inflammations.

In vitro photoinhibition by psoralen and ultraviolet A radiation of human hematopoietic progenitors

The in vitro sensitivity of human hematopoietic progenitors to PUVA, 8-MOP and UVA alone was investigated. 8-MOP alone at final concentrations of 150, 200, 600 and 1,000 ng/ml did not modify colony growth of circulating and bone marrow erythroid (BFU-E), myeloid (CFU-GM) and immature (CFU-GEMM) hematopoietic progenitors obtained from normal controls. The exposure of the same progenitors to increasing doses of UVA, up to 12 J/cm2, progressively decreased hematopoietic colony growth (with estimated 50% inhibition occurring at about 5 J/cm2). In vitro PUVA treatment (8-MOP 200 ng/ml followed by UVA 5 J/cm2) caused 90% growth inhibition of circulating and bone marrow hematopoietic progenitors. In addition, the treatment completely inhibited the formation of spontaneous erythroid colonies, obtained from 5 polycythemic patients, that are considered to be a marker of this neoplastic disease. PUVA cytotoxicity was assessed by the colorimetric MTT assay. The percentage of cell death after PUVA exposure was 29 +/- 10% for both peripheral and bone marrow mononuclear cells. Our findings indicate that 8-MOP alone is not toxic to hematopoietic progenitors whereas UVA treatment determines in vitro a dose-dependent inhibition of the clonogenic capacity of normal hematopoietic cells. PUVA treatment enhances this effect, causing a quite complete inhibition of hematopoietic progenitors colony formation from normal donors and spontaneous BFU-E colony formation from polycythemic patients.

Cytokine expression in psoriatic skin lesions during PUVA therapy

To determine whether an improvement in skin lesions as a result of PUVA therapy may be correlated with changes in cytokine patterns, RT-PCR amplification was used to compare the levels of IL-2, IL-6, IL-8, IL-10, TNF-alpha and IFN-gamma cytokine mRNA expression in serial biopsies from three chronic plaque psoriatic patients. In each case, 3-mm punch biopsies were taken from lesional skin before and during 2-28 days of treatment with PUVA. Total mRNA was extracted from each biopsy, cDNA synthesized, and then amplified by 35 cycles of PCR using cytokine-specific primers. The specificity of the PCR products was confirmed by the Southern blot technique. Substantial levels of specific mRNA for each of the cytokines studied was present in the lesions prior to treatment. In two of the three patients who responded well to PUVA, a reduction in all the cytokines including IL-10 was observed compared with baseline levels. In contrast, PUVA proved to be ineffective in clearing the psoriasis of the third patient whose skin lesions worsened during the course of treatment. This was accompanied by an increase in IFN-gamma but not of the other cytokines investigated, above the pretreatment level. This study showed an association between PUVA-induced resolution and decreases in the levels of various cytokines highly expressed in psoriatic lesions.