Alteration of lymphocyte functions by 8-methoxypsoralen and longwave ultraviolet radiation. I. Suppressive effects of PUVA on T-lymphocyte migration in vitro

Development and Crosslinking Properties of Psoralen-Conjugated Triplex-Forming Oligonucleotides as Antigene Tools Targeting Genome DNA

Psoralen-conjugated triplex-forming oligonucleotides (Ps-TFOs) have been utilized for genome editing and anti-gene experiments for over thirty years. However, the research on Ps-TFOs employing artificial nucleotides is still limited, and their photo-crosslinking properties have not been thoroughly investigated in relation to biological activities. In this study, we extensively examined the photo-crosslinking properties of Ps-TFOs to provide fundamental insights for future Ps-TFO design. We developed novel Ps-TFOs containing 2'-O,4'-C-methylene-bridged nucleic acids (Ps-LNA-mixmer) and investigated their photo-crosslinking properties using stable cell lines that express firefly luciferase constitutively to evaluate the anti-gene activities of Ps-LNA-mixmer. As a result, Ps-LNA-mixmer successfully demonstrated suppression activity, and we presented the first-ever correlation between photo-crosslinking properties and their activities. Our findings also indicate that the photo-crosslinking process is insufficient under cell irradiation conditions (365 nm, 2 mW/cm2 , 60 min). Therefore, our results highlight the need to develop new psoralen derivatives that are more reactive under cell irradiation conditions.

Unique Crosslinking Properties of Psoralen-Conjugated Oligonucleotides Developed by Novel Psoralen N-Hydroxysuccinimide Esters

Psoralens and their derivatives, such as trioxsalen, have unique crosslinking features to DNA. However, psoralen monomers do not have sequence-specific crosslinking ability with the target DNA. With the development of psoralen-conjugated oligonucleotides (Ps-Oligos), sequence-specific crosslinking with target DNA has become achievable, thereby expanding the application of psoralen-conjugated molecules in gene transcription inhibition, gene knockout, and targeted recombination by genome editing. In this study, we developed two novel psoralen N-hydroxysuccinimide (NHS) esters that allow the introduction of psoralens into any amino-modified oligonucleotides. Quantitative evaluation of the photo-crosslinking efficiencies of the Ps-Oligos to target single-stranded DNAs revealed that the crosslinking selectivity to 5-mC is the unique feature of trioxsalen. We found that the introduction of an oligonucleotide via a linker at the C-5 position of psoralen can promote favorable crosslinking to target double-stranded DNA. We believe our findings are essential information for the development of Ps-Oligos as novel gene regulation tools.

Synthesis and Evaluation of Oligonucleotide-Containing 2'-O-{[(4,5',8-trimethylpsoralen)-4'-ylmethoxy]ethylaminocarb-onyl}adenosine as Photo-crosslinkable Gene Targeting Tools

Several psoralen-conjugated oligonucleotides (Ps-Oligos) have been developed as photo-crosslinkable oligonucleotides targeting DNA or RNA. To avoid potential off-target effects, it is important to investigate the selective photo-crosslinking reactivity of Ps-Oligos to DNA or RNA. However, the selectivity of these Ps-Oligos has not been reported in detail thus far. In this study, we evaluated the photo-crosslinking properties of two Ps-Oligos, 5'-Ps-Oligo and a novel Ps-Oligo containing 2'-O-{[(4,5',8-trimethylpsoralen)-4'-ylmethoxy]ethylaminocarbonyl}adenosine (APs2-Oligo). Notably, 5'-Ps-Oligo preferentially crosslinked with DNA, whereas APs2-Oligo preferentially crosslinked with RNA. These results demonstrate the interesting crosslinking properties of Ps-Oligos, which will provide useful information for the molecular design of novel Ps-Oligos in future studies.

Comparison of Narrowband UV-B With Psoralen-UV-A Phototherapy for Patients With Early-Stage Mycosis Fungoides: A Systematic Review and Meta-analysis

Importance

Phototherapy is one of the mainstays of treatment for early mycosis fungoides (MF). The most common modalities are psoralen-UV-A (PUVA) and narrowband UV-B (NBUVB).

Objective

To compare the efficacy and adverse effects of PUVA vs NBUVB in early-stage MF.

Data Sources

A systematic review was performed by searching Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Ovid Medline, PubMed, Cochrane Library, American College of Physicians ACP Journal Club, and Database of Abstracts of Review of Effectiveness from inception to March 30, 2018. UV A, PUVA, mycosis fungoides, Sézary syndrome, cutaneous T-cell lymphoma, UV B, and UVB were used as either key words or MeSH terms.

Study Selection

Studies of cohorts with histologically confirmed early-stage MF, defined as stages IA, IB, and IIA, that compared PUVA vs NBUVB, had at least 10 patients in each comparator group, and reported outcomes of response to therapy. Exclusion criteria were studies with patients with stage IIB or higher MF, pediatric patients, fewer than 10 in each comparator group, noncomparative studies, case reports, and abstract studies.

Data Extraction and Synthesis

The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline was followed. Data were pooled using a random-effects model with odds ratio (OR) as effect size.

Main Outcomes and Measures

Main outcomes were complete response rate, partial response rate, disease recurrence, and adverse effects, including erythema, nausea, pruritus, phototoxic effects, dyspepsia, and pain.

Results

Seven studies were included with a total of 778 patients (405 of 724 [55.9%] men; mean age, 52 years); 527 were treated with PUVA and 251 with NBUVB. Most of the included studies were of poor to moderate quality. Any response was found in 479 of the 527 (90.9%) patients treated with PUVA vs 220 of 251 (87.6%) treated with NBUVB (OR, 1.40; 95% CI, 0.84-2.34; P = .20). Complete response was found in 389 of 527 (73.8%) patients who received PUVA vs 156 of 251 (62.2%) who received NBUVB, which was statistically significant (OR, 1.68; 95% CI, 1.02-2.76; P = .04). Partial response was similar (90 of 501 [18.0%] vs 64 of 233 [27.5%]; OR, 0.58; 95% CI, 0.33-1.04; P = .07). No significant difference was found between PUVA and NBUVB in terms of adverse effects of erythema (38 of 527 [7.2%] vs 17 of 251 [6.7%]; P = .54), nausea (10 of 527 [1.9%] vs 3 of 251 [1.2%]; P = .72), pruritus (2 of 527 [0.4%] vs 4 of 251 [1.7%]; P = .26), phototoxic effects (7 of 527 [1.4%] vs 2 of 251 [0.9%]; P = .72), dyspepsia (6 of 527 [1.2%] vs 0 of 251 [0%]; P = .59), or pain (0 of 527 [0%] vs 2 of 251 [0.9%]; P = .50).

Conclusions and Relevance

The findings suggest that PUVA is a potential alternative to NBUVB in the management of early-stage MF. These findings have implications for clinicians involved in the management of early-stage MF.

Efficacy of narrowband UVB vs. PUVA in patients with early-stage mycosis fungoides

INTRODUCTION

Mycosis fungoides (MF) is a non-Hodgkin's T-cell lymphoma of the skin that often begins as limited patches and plaques with slow progression to systemic involvement. Narrowband ultraviolet (UV) B therapy has been proven to be an effective short-term treatment modality for clearing patch-stage MF. The effect of psoralen plus long-wave ultraviolet A (PUVA) in the treatment of patch- and plaque-type MF has also been thoroughly documented.

OBJECTIVES

The purpose of this study was to compare the efficacy and safety of narrowband UVB and PUVA in patients with early-stage MF.

METHODS

We analysed the response to treatment, relapse-free survival and irradiation dose in 114 patients with histologically confirmed early-stage MF (stage IA, IB and IIA).

RESULTS

A total of 95 patients were treated with PUVA (83.3%) and 19 with narrowband UVB (16.7%). With PUVA, 59 patients (62.1%) had a complete response (CR), 24 (25.3%) had a partial response (PR) and 12 (12.6%) had a failed response. Narrowband UVB led to CR in 12 (68.4%) patients, PR in 5 (26.3%) patients and a failed response in 1 (5.3%) patient. There were no differences in terms of time to relapse between patients treated with PUVA and those treated with narrowband UVB (11.5 vs. 14.0 months respectively; P = 0.816). No major adverse reactions were attributed to the treatment.

CONCLUSIONS

Our results confirm that phototherapy is a safe, effective and well-tolerated, first-line therapy in patients with early-stage cutaneous T-cell lymphoma, with prolonged disease-free remissions being achieved. It suggests that narrowband UVB is at least as effective as PUVA for treatment of early-stage MF.

The optimal use of bexarotene in cutaneous T-cell lymphoma

The management goal in cutaneous T-cell lymphomas (CTCLs) is to improve symptoms and induce remission. Early-stage disease is generally treated with skin-directed therapies. However, if these do not control the disease, systemic therapy becomes necessary. Bexarotene, a novel rexinoid, is an oral, noncytotoxic drug that has been approved in Europe for the treatment of refractory advanced-stage CTCL and in the U.S.A. for refractory CTCL. We provide guidance on the use of bexarotene in the management of CTCL, based on data from phase II/III clinical trials and the authors' clinical experience, and suggest how the potential of the drug can be maximized. The clinical trial results with bexarotene are reviewed, especially in comparison with interferon-alpha, which is the other commonly used noncytotoxic systemic therapy for CTCL. A treatment algorithm for bexarotene in refractory CTCL is suggested. As bexarotene may take time to achieve a maximum response, this algorithm recommends that therapy should be continued for a sufficient period to allow for a delayed onset of action. In addition, possible combination therapies with bexarotene are discussed. We conclude that bexarotene is effective in the management of CTCL, and has the advantage of oral administration. An on-going randomized clinical trial comparing psoralen plus ultraviolet A (PUVA) with PUVA plus bexarotene will provide valuable information about this combination regimen in early-stage disease, but further data are needed on the relative efficacies of other combination therapies with bexarotene in CTCL.

Narrow band UVB (311 nm), psoralen UVB (311 nm) and PUVA therapy in the treatment of early-stage mycosis fungoides: a right-left comparative study

BACKGROUND

Psoralen ultraviolet A (PUVA) is a widely used first-line therapy for treatment of early cutaneous T-cell lymphoma. Narrow band UVB (UVB-NB) (311 nm) has been recently introduced as another effective line of treatment. It is postulated that the efficacy of UVB-NB could be enhanced by addition of psoralen.

AIM

The aim of the present work was to compare the clinical and histopathologic efficacy of PUVA and UVB-NB in the treatment of early-stage MF (stages IA, IB and IIA), and to evaluate whether psoralen adds to the efficacy of UVB-NB or not.

PATIENTS AND METHODS

Twenty patients (stage IA, IB or IIA) were divided into two equal groups: group I received UVB-NB on the right body half vs. PUVA on the left side of the body for 48 sessions, and group II received PUVB-NB on the right side of the body vs. PUVA on the left side for 36 sessions. The sessions were administered three times weekly.

RESULTS

In group I, almost equal results were obtained on both sides, i.e., UVB-NB and PUVA were equally effective in the treatment of early stages of MF, both clinically and histopathologically. In group II, PUVB-NB was found to be as effective as conventional PUVA in the treatment of early-stage mycosis fungoides, also on both clinical and histopathological grounds.

CONCLUSION

UVB-NB phototherapy should be included among the initial therapeutic options of mycosis fungoides in view of its efficacy, convenience, and likelihood of fewer long-term adverse effects. Addition of psoralen does not seem to enhance its therapeutic efficacy.

Therapeutic and prophylactic effects of PUVA photochemotherapy on atopic dermatitis-like lesions in NC/Nga mice

BACKGROUND

Psoralens and ultraviolet A radiation (PUVA) photochemotherapy has been used for severe cases of atopic dermatitis (AD). To understand the mechanisms of action is important for the choice of treatments. AD-like lesions can be induced experimentally in NC/Nga mice.

OBJECTIVES

To evaluate clinically and histologically the therapeutic and prophylactic effects of PUVA on AD-like dermatitis using NC/Nga mice.

METHODS

PUVA therapy was performed with intraperitoneal injection of 4 mg/kg of 8-methoxypsoralen (8-MOP) and 4 J/cm(2)-UVA irradiation before and after development of AD-like lesions in NC/Nga mice which had been maintained in a conventional room (Conv-NC/Nga mice). Clinical skin conditions were evaluated periodically by a clinical severity score defined. Lesions were histologically examined in haematoxylin-eosin or toluidine blue-stained sections. Plasma levels of total IgE were measured at various time points.

RESULTS

In Conv-NC/Nga mice infested with mite, AD-like lesions started to develop at 8 week of age and thereafter increased in severity score. PUVA therapy at lower does than minimal phototoxic dose suppressed the development of dermatitis and was also therapeutically effective against established lesions. Proliferation of dermal mast cells in AD-like lesions was suppressed, but IgE hyperproduction was not changed after PUVA.

CONCLUSIONS

These observations suggest that PUVA photochemotherapy reveals not only therapeutic but also prophylactic effects on human AD.

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.

Current management strategies for cutaneous T-cell lymphoma

Cutaneous T-Cell Lymphoma is a group of lymphomas characterized by a malignant proliferation of skin homing T cells. Prognosis is generally good and treatment is based on the stage of the disease with the goal of inducing remission. Patients with disease limited to the skin in the form of patches and plaques respond best to "skin directed therapy" with topical agents including corticosteroids, nitrogen mustard, carmustine, bexarotene gel, as well as phototherapy with ultraviolet B light, PUVA, or photodynamic therapy. Tazarotene and imiquimod show potential in the treatment of early CTCL. Patients with disease resistant to treatment or with advanced disease require more aggressive therapy in the form of total skin electron beam radiation, biologic response modifiers including interferon alpha, bexarotene, denileukin diftitox, extracorporeal photochemotherapy or combination therapy. The use of chemotherapy is used primarily for palliation. Allogeneic hematopoetic stem cell transplantation may represent a successful treatment for treatment resistant disease.

Treatment of persistent severe atopic dermatitis in 113 Japanese patients with oral psoralen photo-chemotherapy

Oral administration of psoralen and whole body exposure to UVA (oral PUVA) has been used for the treatment of 113 patients with severe atopic dermatitis (AD). 8-Methoxypsoralen (8-MOP) was given at a dose of 0.5-0.6 mg/kg two hours prior to UVA (3-8 J/cm2) irradiation. Patients were treated three times a week while hospitalized. Other medications which had been given before PUVA therapy were permitted. At four and eight weeks after PUVA therapy, the severity score of AD had decreased by 51% and 80%, and the cumulative doses of UVA were 51.2 J/cm2 and 115.3 J/cm2, respectively. The amounts and strength of topical cortico-steroids were decreased during PUVA therapy. No adverse effects that required discontinuation of the PUVA therapy were observed. After discharge, maintenance therapy with UVB phototherapy and/or conventional treatment of AD kept the patients in remission in the outpatient clinic. The QOL of patients was greatly improved. Photochemotherapy with oral 8-MOP can be indicated in patients with severe, widespread AD, especially if standard therapy fails. This is the first report of oral PUVA therapy in a large series of Japanese patients with AD.

Narrowband UVB and psoralen-UVA in the treatment of early-stage mycosis fungoides: a retrospective study

BACKGROUND

Treatment of early-stage mycosis fungoides (MF) consists of topical steroids, phototherapy (UVB), photochemotherapy (psoralen plus UVA [PUVA]), topical nitrogen mustard, or total skin electron-beam irradiation. It has been reported that the same effective UVB dose is safer than PUVA regarding carcinogenicity and produces fewer side effects. Narrowband UVB (311 nm) results in less irritation and erythema and is more effective compared with broadband UVB.

OBJECTIVE

Our purpose in this retrospective study was to analyze the response to treatment, relapse-free interval, and irradiation dose in 56 patients with early-stage MF (stage Ia and Ib). A total of 21 patients were treated with narrowband UVB (311 nm); 35 patients were treated with PUVA.

RESULTS

Narrowband UVB treatment led to complete remission in 17 of 21 patients (81%), partial remission in 4 of 21 (19%), and none showed progressive disease. PUVA treatment led to complete remission in 25 of 35 patients (71%), partial remission in 10 of 35 (29%), and none showed progressive disease. The mean relapse-free interval for patients treated with UVB was 24.5 months (range, 2-66 months) and for patients treated with PUVA, 22.8 months (range, 1-43 months).

CONCLUSION

Narrowband UVB therapy for patients with early-stage MF is an effective treatment modality. It has several advantages over treatment with broadband UVB and PUVA. When treating patients with early-stage MF it may be beneficial to start with narrowband UVB therapy and, if there is progression or no response, switch to PUVA therapy.

Treatment of peripheral blood mononuclear cells with 8-methoxypsoralen plus ultraviolet A radiation induces a shift in cytokine expression from a Th1 to a Th2 response

Treatment with 8-methoxypsoralen plus ultraviolet A radiation and extracorporeal photochemotherapy (photopheresis) are widely used for the treatment of psoriasis and other inflammatory skin diseases, graft-versus-host disease, and mycosis fungoides. As the ratio of Th1 and Th2 cells appears to be critical for pathogenesis and progression of these disorders the effect of psoralen plus ultraviolet A on Th1 and Th2 cytokine production by CD4+ lymphocytes was investigated. Human peripheral blood lymphocytes were incubated in the presence of anti-CD3, rh-IL2, and rh-IL4 for 48 h. After subsequent stimulation with rh-IL2 and rh-IL4 for 72 h cells were treated with 8-methoxypsoralen (100, 500, 1000 ng per ml) plus ultraviolet A (2 J per cm2) and incubated for a further period of 5 h in the presence of ionomycine, phorbol-12-myristate acetate and monensin. Fluorescence-activated cell sorter analysis revealed a significant reduction of interleukin-2- and interferon-gamma-producing CD4+ cells upon psoralen plus ultraviolet A treatment depending on the concentration of 8-methoxypsoralen. In contrast, interleukin-4-producing CD4+ cells were increased, indicating a shift from Th1 to a Th2 cell cytokine profile upon psoralen plus ultraviolet A treatment. These results indicate that 8-methoxypsoralen photochemotherapy of lymphocytes is able to modulate their Th1/Th2 distribution. Inhibition of Th1 cytokine expression by psoralen plus ultraviolet A might help to explain its beneficial effects in the treatment of Th1 dominated skin diseases.

Indications and action mechanisms of phototherapy

Recently phototherapy has become one of the most commonly used modalities for the treatment of a variety of skin diseases, although the action mechanisms have not been fully understood. The inhibitory effect of UVR on DNA synthesis may be one of the actions for proliferating skin diseases. However, phototherapy is also used for the treatment of allergic or autoimmune diseases. It has been confirmed that the skin is an important immunologic organ whose constitutive cells are all involved in immunologic reactions. We have investigated the effects of PUVA and UVB radiation on the immunocompetent cells, including Langerhans cells, T lymphocytes, mast cells, endothelial cells and natural killer cells. Exposure to UVR inhibits contact sensitization to haptens applied not only to the irradiated skin area but also to the non-irradiated distant skin when the exposure dose is relatively high and/or the application skin area is large. In addition, hapten-specific tolerance develops by the generation of suppressor T cells. Phototherapy is also useful for immediate type hypersensitivity such as urticaria. Action mode in the case may be the inhibitory effects of UVR on histamine release from mast cells. The results obtained from these experiments suggest that phototherapy exerts its anti-allergic and anti-inflammatory effects through immunosuppression.

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.

Suppressive effect of ultraviolet (UVB and PUVA) radiation on superantigen production by Staphylococcus aureus

It is well known that Staphylococcus aureus (S. aureus) proliferates on the moist skin lesion of atopic dermatitis. Reduction of bacteria colonization from skin lesions by antibiotics has been reported to be effective for the treatment of atopic dermatitis. S. aureus produces superantigens which can activate T cells and possibly enhance the inflammatory reaction. Photo(chemo)therapy has been successfully used for the treatment of severe cases of atopic dermatitis. We have previously reported that photo(chemo)therapy had bacteriostatic effect on S. aureus. Now we examined the effect of UVB and psoralen plus UVA (PUVA) on superantigen production from S. aureus. We isolated S. aureus from six atopic dermatitis patients. S. aureus was irradiated in vitro with UVB (0, 5, 10 mJ/cm2) or PUVA (0.001% psoralen plus 0, 5, 10 mJ/cm2 UVA) and incubated 4 h with 100 strokes per min. After incubation, the amounts of superantigens in the supernatant were measured using ELISA kit. The production of superantigens decreased in an ultraviolet dose-dependent manner. The suppressive effects of UV radiation on superantigen production may be involved in the therapeutic efficacy of photo(chemo)therapy for atopic dermatitis.

PUVA treatment selectively induces a cell cycle block and subsequent apoptosis in human T-lymphocytes

Psoralen plus UVA (320-400 nm radiation; PUVA) is a highly effective therapy for cutaneous diseases caused by skin infiltration with normal or neoplastic T-lymphocytes. In comparing the effects of pharmacologically relevant, low-dose PUVA treatment on growth of human keratinocytes, peripheral blood leukocytes (PBMC), and T-lymphocyte cell lines, we determined that PBMC or T-lymphocytes were > 50-fold more sensitive to cytotoxic effects of PUVA, while antiproliferative effects were produced by similar PUVA levels in all cell types. Low doses of PUVA (10 ng/mL 8-methoxypsoralen and 1-2 J/cm2) were highly cytotoxic for phytohemagglutinin-activated normal lymphocytes or transformed T-lymphocytes as assessed by two viability assays and by flow cytofluorometry. Altered lymphocyte morphology, nuclear fragmentation, TUNEL+ nuclei or nuclear fragments, and the appearance of a sub-G1 DNA peak indicated that cell death occurred by apoptosis, beginning about 1 day after PUVA treatment and continuing for several days thereafter. From assessment of cell cycle progression in mimosine-synchronized cells, PUVA treatment markedly slowed cell cycle progression, eventually producing cell cycle arrest and apoptotic entry. We propose that the probable basis for disease remissions (psoriasis, cutaneous T-cell lymphoma) produced by PUVA treatment is through selective cytotoxic effects on clonal T-lymphocyte populations that are concentrated in diseased skin.

In vitro granuloma formation by spleen cells treated with psoralen plus long-wave ultraviolet radiation

In vitro granulomas are induced by culturing murine spleen cells with artificial microparticles, dextran beads. In the presence of 0.5 microgram/mL 8-methoxypsoralen, UVA radiation (0.2-2.0 J/cm2) suppressed granuloma formation in a UVA dose-dependent manner. The doses of PUVA did not affect the cell viability as assessed by trypan blue exclusion. The time course of granuloma formation in 0.5 J/cm2 PUVA-treated cells was similar to that of normal spleen cells, with a maximum granuloma index at day 3 of culture, although a 49-63% suppression of granuloma formation was observed. PUVA-treated, nonadherent cells produced the same granuloma index when cultured with normal adherent cells. In contrast, a smaller granuloma index was observed in PUVA-treated adherent cells even when they were cultured with normal nonadherent cells. These data suggest that PUVA alters macrophages, resulting in the suppression of granuloma formation in vitro.

Ultraviolet radiation suppresses mouse-ear edema induced by topical application of arachidonic acid

The effect of ultraviolet (UV) radiation on arachidonic acid (AA) cascade was examined using an in vivo model. Mouse ear lobes were painted with 1 mg AA, and the maximum response of ear swelling was measured 1 h after challenge. Arachidonic-acid-induced ear swelling was significantly suppressed by preexposure to topical psoralen plus noninflammatory doses of long-wave UV radiation (PUVA) or middle-wave UV (UVB) radiation. Ultraviolet radiation may interfere with AA pathways to suppress ear swelling since AA-induced ear swelling is considered to be mediated by metabolites derived from exogenous AA. The results may relate to the therapeutic mechanisms of UV radiation in psoriasis in which the eicosanoid cascade is involved.

PUVA therapy decreases HLA-DR+ CDIa+ Langerhans cells and epidermal cell antigen-presenting capacity in human skin, but flow cytometrically-sorted residual HLA-DR+ CDIa+ Langerhans cells exhibit normal alloantigen-presenting function

We have investigated the effects of PUVA therapy on human Langerhans cell (LC) immunophenotype and function. Epidermal sheets were obtained from exposed, and control shielded, forearm skin at the end of a course of PUVA therapy, in patients receiving treatment routinely for a variety of dermatoses. PUVA therapy decreased the overall number of HLA-DR+CDIa+ LCs in epidermal sheets, and in epidermal cell (EC) suspensions examined using a fluorescence activated cell sorter (FACS). PUVA therapy also reduced the overall EC allostimulatory capacity in the allogeneic epidermal cell-lymphocyte reaction (ELR), and the capacity of ECs to present tetanus toxoid to, and augment concanavalin A-mediated stimulation of, lymphocytes in the autologous ELR. Depressed allostimulation by ECs from PUVA-treated skin could not be restored by indomethacin (added to block prostaglandin synthesis). The reductions in LC numbers and EC allostimulatory capacity varied according to dose, and time since cessation, of PUVA therapy, and in individual patients were of comparable degree. By contrast, the allostimulatory capacity of residual LCs from PUVA-treated skin (purified using the FACS) did not differ from that of purified control LCs. PUVA-induced suppression of cutaneous immune responses, therefore, results at least in part from an overall impairment of EC antigen-presenting capacity. Residual HLA-DR+CDIa+ LCs in PUVA-treated skin which retain their alloantigen-presenting function may represent a subgroup of PUVA-resistant LCs; alternatively, these cells may be as yet unaffected because they have only recently migrated into the epidermis.

Successful resolution of severe perianal ulceration with photochemotherapy (PUVA)

We report a case of recurrent perianal ulceration associated with gastrointestinal symptoms, but without evidence of underlying disease, that responded to a course of photochemotherapy (PUVA).

Psoralen photochemotherapy

Psoralens and sunlight have been used by the Egyptians and Indians for hundreds of years for the treatment of vitiligo. The combination of oral psoralens and artificial ultraviolet A (PUVA) therapy was approved for the management of severe psoriasis by the Food and Drug Administration in 1982. Since then PUVA therapy has been found to be an effective modality in the treatment of many cutaneous conditions. When properly administered, the major short-term side effects are minimal. The long-term side effects may include an increased risk of squamous cell carcinoma, atypical cutaneous pigmentation, accelerated skin aging, and ophthalmologic abnormalities. By careful patient selection and limiting the cumulative UVA dosage and frequency by using combinations or alternative therapies, these side effects may be reduced. Continued reporting of carefully carried out long-term prospective studies will provide us with more knowledge of the long-term side effects of PUVA. In the meantime, for each patient on PUVA therapy the risk/benefit ratio should be carefully considered.

Alteration of lymphocyte functions by 8-methoxypsoralen and long-wave ultraviolet radiation. II. The effect of in vivo PUVA on IL-2 production

Our previous studies demonstrated that psoralen plus long-wave ultraviolet radiation (PUVA) treatment inhibited certain T-lymphocyte functions, such as locomotive ability. To further analyze the effects of PUVA on T-lymphocyte function, we investigated the ability of mouse spleen cells to produce interleukin 2 (IL-2) after treatment of the mice in vivo with PUVA. Interleukin 2 production was impaired in cells from PUVA-treated mice compared with those from UVA-irradiated, 8-methoxypsoralen-treated, or normal mice. This impairment was not dose dependent, over the dose range of UVA (2-20 J/cm2) examined. Interleukin 2 production was markedly suppressed on day 3 after PUVA and returned to normal by day 7 after the treatment. Topical treatment of the mice with croton oil did not affect IL-2 production of their spleen cells. This result indicates that cutaneous inflammation per se may not be responsible for the suppressive effect of PUVA on IL-2 production. Addition of exogenous IL-1 did not reconstitute the decreased ability of spleen cells to produce IL-2 in vitro, indicating that PUVA affected primarily IL-2 producing cells. These suggest that impaired IL-2 production may account for some of the immune dysfunction observed in PUVA-treated animals.

Psoralens and related compounds in the treatment of psoriasis

PUVA therapy has radically altered the management of severe psoriasis. It is of greatest benefit in those patients with extensive involvement, and in those unresponsive to conventional therapy. The long term side effects of PUVA currently limit its use to patients with disabling disease. The full extent of long term side effects has yet to be defined. In order to reduce the toxicity and improve the efficacy of PUVA, a better understanding of the molecular aspects of psoralen-DNA interaction, DNA repair, and mutagenesis is required. The action spectrum of PUVA in clearing psoriasis has yet to be defined. By limiting the spectrum of UVA exposure it may be possible to reduce some of the toxic effects of PUVA. The recent advances in the formulation of 8-MOP preparations has yielded a drug with more predictable pharmacokinetics and clinical response. Further research with newer psoralens may produce more effective and less toxic compounds. In the last ten years, PUVA has been both a valuable addition to dermatologists' clinical armamentarium and a useful tool in increasing our understanding of cellular biology and the interaction between ultraviolet radiation and biologic systems.