Methotrexate inhibits the human C5a-induced skin response in patients with psoriasis

Current Thoughts on the Use of Methotrexate in Patients with Psoriasis

Background:

There are many problems associated with the use of methotrexate in the treatment of psoriasis.

Objective:

We will attempt to assist the clinician in resolving some of these problems.

Methods:

This article is a summary of a Round Table Discussion on methotrexate held at the Canadian Dermatology Association meeting at Whistler, BC, July 1995; of a Continuing Medical Education meeting on methotrexate at Langdon Hall, Cambridge, ON, May 1996; and our review of the pertinent literature.

Results:

We recommend routine folic acid supplementation in patients receiving methotrexate. A baseline pretreatment liver biopsy is probably not indicated in patients without clinical or laboratory evidence of liver disease; and patients on 15 mg or less of methotrexate per week with normal liver function may not need liver biopsy.

Conclusion:

Liver biopsy of patients on methotrexate for psoriasis may not be necessary.

Inhalation delivery of anticancer agents via HFA-based metered dose inhaler using methotrexate as a model drug

In the present study, the feasibility of delivering anticancer drugs via metered dose inhaler (MDI) was demonstrated using methotrexate (MTX) as a model anticancer drug. MDI formulations of MTX were prepared using hydrofluoroalkane-134a containing 0.67% MTX and 10% ethyl alcohol. The particle size of MTX was reduced by cryo milling with or without a surfactant (Pluronic F77) and the milled drug was employed for MDI formulations, which were subsequently evaluated for their medication delivery, mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD). Further, the efficacy of aerosolized MTX was evaluated by determining the in-vitro cytotoxicity of MTX against HL-60 cells using a six-stage viable impactor and the induction of apoptosis in HL-60 cells by acridine orange staining. Our results indicate that MTX aerosols having an MMAD varying between 2.2 and 3.2 microm (GSD 2.6-3.7) with a respirable fraction varying between 14.2 and 17.1% could be obtained by using MTX, which was cryo milled either alone or in combination with Pluronic F77. Exposure of HL-60 cells plated in third, fourth, fifth, and sixth stages of viable impactor to two actuations of MDI showed a cell kill of greater than 50%. Further, aerosolized MTX was found to induce apoptosis in HL-60 cells, as assessed by the morphological examination of the cells with fluorescent and confocal microscopy. Our results demonstrate that it is possible to deliver cytotoxic concentrations of MTX in an in vitro system simulating the lower respiratory tract (by using a six-stage viable impactor) via MDI and the cytotoxicity of the aerosolized MTX could be further improved by the optimization of the aerodynamic size.

Methotrexate as a steroid sparing agent for asthma in adults

BACKGROUND

Sustained oral corticosteroid use can lead to complications, so there is interest in identifying agents that can reduce oral steroid use in people with asthma. Methotrexate has attracted attention as a possible steroid sparing agent in patients with chronic oral steroid dependent asthma.

OBJECTIVES

The objective of this review was to assess the effects of adding methotrexate to oral corticosteroids in adults with stable asthma who are dependent on oral corticosteroids.

SEARCH STRATEGY

The Cochrane Airways Group trials register and reference lists of identified articles were searched.

SELECTION CRITERIA

Randomised trials of the addition of methotrexate compared with placebo in adult steroid dependent asthmatics. Duration of therapy needed to be at least 12 weeks.

DATA COLLECTION AND ANALYSIS

Trial quality was assessed and data extraction was carried out by two reviewers independently. Study authors were contacted for missing information.

MAIN RESULTS

Ten trials involving a total of 185 people were included. Study design and quality, corticosteroid dosages and outcomes varied widely. There was a reduction in oral corticosteroid dose favouring methotrexate in parallel trials (weighted mean difference -4.1 mg per day, 95% confidence interval -6.8 to -1.3) and also in cross-over trials (weighted mean difference -2.9 mg per day, 95% confidence interval -5.9 to -0.2). There was no difference between methotrexate and placebo for forced expiratory volume in one minute (weighted mean difference 0.12 litre, 95% confidence interval -0.21 to 0.45). Hepatotoxicity was a common adverse effect with methotrexate compared to placebo (odds ratio 6.9, 95% confidence interval 3.1 to 15.5).

REVIEWER'S CONCLUSIONS

Methotrexate may have a small steroid sparing effect in adults with asthma who are dependent on oral corticosteroids. However, the overall reduction in daily steroid use is probably not large enough to reduce steroid-induced adverse effects. This small potential to reduce the impact of steroid side-effects is probably insufficient to offset the adverse effects of methotrexate.

Risk-benefit assessment of methotrexate in the treatment of severe psoriasis

Methotrexate is an established and highly effective systemic treatment for severe psoriasis, including the pustular and erythrodermic forms. It has been widely used during the last 3 decades. For this reason, the long term adverse effects of methotrexate are well known, in contrast to other relatively new systemic treatments like cyclosporin and retinoids. The most frequent adverse effects occurring during methotrexate therapy are abnormal liver function tests, nausea and gastric complaints. The most feared adverse effects are myelosuppression and hepatotoxicity. Because hepatotoxicity is related to a high cumulative dose of methotrexate, rotational therapy or an intermittent instead of a continuous treatment schedule are advised. The histological assessment of liver biopsies, according to the international guidelines, remains the gold standard for detection of liver damage until equally reliable noninvasive screening methods for liver damage--tentatively dynamic hepatic scintigraphy (DHS) or measurement of levels of serum aminoterminal propeptide of type III procollagen--are well evaluated. Low dose methotrexate therapy is relatively well tolerated, provided that there is careful patient selection and regular monitoring for adverse effects and drug interactions during methotrexate therapy is carried out. The long term clinical efficacy and relative safety of methotrexate remain impressive.

Methotrexate suppresses nitric oxide production ex vivo in macrophages from rats with adjuvant-induced arthritis

We examined the effects of methotrexate (MTX) on the level of nitric oxide (NO) produced by peritoneal macrophages from rats with adjuvant-induced arthritis (AA) ex vivo. During the development of AA, paw swelling increased and LPS enhanced the capacity of peritoneal macrophages to produce NO and prostaglandin E2 (PGE2). MTX (0.1 mg/kg, p.o.) treatment for 21 days reduced the paw swelling, and inhibited the increased NO and PGE2 production. However, when MTX (0.1 mg/kg, p.o.) was administered to rats with established AA, these parameters were not significantly influenced. In normal rats, MTX (0.1 mg/kg, p.o.) treatment for 21 days did not change NO and PGE2 production of LPS-stimulated macrophages. On the other hand, macrophages from normal and AA rats cultured in the presence of MTX (1, 10 and 100 microM), were activated by LPS in vitro. MTX did not influence NO or PGE2 production by LPS-stimulated macrophages in normal and AA rats. By contrast, indomethacin (IM) (1.0 mg/kg, p.o.) treatment for 21 days reduced the paw swelling, and inhibited NO and PGE2 production in AA rats. IM inhibited significantly PGE2 production, but did not influence NO production by LPS-stimulated macrophages in vitro. These results suggest that MTX treatment reduces NO production in peritoneal macrophages in AA rats, and these actions of MTX may have an inhibitory effect without the modulation of PGE2.

Methotrexate maintains bone mass by preventing both a decrease in bone formation and an increase in bone resorption in adjuvant-induced arthritic rats

We examined the effects of low doses methotrexate (MTX) and indomethacin (IND) on bone mass and turnover in normal male Sprague-Dawley rats and those with adjuvant-induced arthritis. Normal and the adjuvant (heat-killed mycobacterium)-injected rats, 6 weeks of age, were given MTX at daily doses of 0.05, 0.1, or 0.2 mg/kg body weight (BW) or IND at a daily dose of 1.0 mg/kg BW. Rats were killed at the start, or at 14 and 28 days. In normal rats, the administration of these agents did not change the lumbar and femoral BMD values, nor did the serum osteocalcin or urinary deoxypyridinoline (D-Pyr) levels. Lumbar trabecular osteoclast number (Oc.N/BS) and osteoclast surface (Oc.S/BS) were decreased in the rats given IND. In the arthritic rats, the administration of MTX did not prevent an early increase of paw edema in the adjuvant-injected limb, but late inflammatory edema was alleviated in the non-injected limb. However, MTX administration at a dose of 0.1-0.2 mg/kg BW maintained an age-dependent increase in the lumbar and femoral BMD values. While serum osteocalcin levels were decreased and urinary D-Pyr values were increased in the arthritic control rats, these bone markers remained at the levels of the normal rats. Decreases in mineral apposition rate (MAR) and bone formation rate (BFR/BS) and increases in the trabecular Oc.N/BS and Oc.S/BS values were prevented by MTX. While IND almost completely prevented inflammatory paw edema, it did not improve the parameters of bone formation. An increase in osteoclasts was prevented and the osteopenia in the lumbar and the femoral bone was only partially prevented by IND. These data suggest that MTX improves bone mass and turnover in the arthritic rat, in which several cytokines that affect bone cells are involved. An increase in bone resorption may be due to prostaglandins, but bone formation defect was suggested to be due to other cytokines such as IL-1, IL-6, and TNF-alpha in this model.

Methotrexate for psoriasis

Methotrexate is an effective antipsoriatic agent and has been widely used to treat severe psoriasis since the 1960s. It is especially useful in acute generalized pustular psoriasis, psoriatic erythroderma, psoriatic arthritis and for extensive chronic plaque psoriasis in patients who are inadequately controlled by topical therapy alone. It has not, however, been formally compared with other systemic treatments for severe psoriasis such as cyclosporin, retinoids or photochemotherapy with psoralen and UVA (PUVA), but in comparison with these other therapies it is inexpensive, with correct use, its safety profile is favourable. In summary, therefore, it can be used as a short-term option to gain control of unstable psoriasis such as pustular psoriasis or erythroderma before returning to other modes of treatment, or more often, as long-term maintenance treatment. The most important potential side-effect is acute myelosuppression, which is the cause of most of the rare deaths attributable to this therapy for psoriasis. Myelosuppression is more likely in the elderly, in patients with renal impairment and/or folate depletion, and with overdose or drug interactions. Long-term therapy carries with it a risk of liver fibrosis which is related to the dosage regimen employed, and is increased by exposure to other hepatic toxins, particularly alcohol. The correlation between the risk of development of liver fibrosis, cumulative lifetime dose and duration of treatment with methotrexate is not clear-cut, but may have been overstated in some studies.

Determination of methotrexate in serum by high-performance liquid chromatography

A sensitive high-performance liquid chromatographic method with ultraviolet detection was developed to quantitate methotrexate in serum-based calibrators, controls and patient samples. Sample clean-up was achieved with C18 Sep-Pak Classic cartridges. The chromatographic separation was accomplished on a 5-microns Ultrasphere ODS Beckman column. 8-Chlorotheophylline was used as an internal standard. The method was validated by recovery, linearity, accuracy and precision studies. Two standard curves were constructed to cover the high and the low ends of the calibrator range (0.05-1.0 mumol/l). Response was found linear over the whole range of the calibrator set with a correlation coefficient of 0.999 and 1.00 for the low-level and the high-level curves, respectively. Accuracy varied from 12% at the lowest level to 1.2% at the highest level. The precision study showed a C.V. of 14.4% at the lowest level and 3.3% at the highest level.

Complement peptides C3a- and C5a-induced mediator release from dissociated human skin mast cells

The complement peptides C3a and C5a have been shown previously to release histamine from human basophils but not human lung mast cells. As skin mast cells differ from those of the lung in both immunocytochemical and functional properties, we examined the ability of these anaphylatoxins to release preformed and newly generated mediators from human dispersed skin mast cells. In concentration-response studies, both C3a and C5a released histamine in a concentration related manner with C5a being 40-50 times more potent. However, the extent of histamine, 15-20%, was considerably less than that released from basophils. This was not due to catabolism of the peptides by mast cell proteases, mast cell supernatants that contained C5a being effective in releasing basophil histamine. Removal of the C-terminal arginine from C3a and C5a abolished their activity on skin mast cells. In time-course studies, histamine release induced by C3a and C5a was complete within 15 seconds. Complement-induced histamine release is a non-cytotoxic process as evidenced by 2-deoxy-D-glucose and antimycin A, inhibitors of glycolysis and oxidative phosphorylation, respectively. In contrast to IgE-dependent stimulation, anaphylatoxin-induced histamine release from human skin mast cells is independent of extracellular calcium. Both C3a and C5a at concentrations that induced 10-16% net histamine release caused a negligible release of the newly generated mediator, PGD2. The results suggest that C3a and C5a stimulate human skin mast cells in a manner similar to substance P and related basic secretagogues. However, the activation site for C3a and C5a appears to be different to that for substance P as the substance P antagonist (D-Pro4, D-Trp7,9,10) SP4-11 inhibited histamine release stimulated by substance P but not that induced by C3a and C5a.

The role of methotrexate in the management of steroid-dependent asthma

Severe asthma often requires high-dose corticosteroid therapy. However, steroid therapy is fraught with many side effects. There are conflicting reports in the literature regarding the role of methotrexate in reducing the steroid requirements of these patients. This study examined the role of low-dose methotrexate in the management of steroid-dependent asthma. Eleven subjects with stable steroid-dependent asthma were enrolled in a placebo-controlled double-blind crossover trial. Patients received methotrexate, 15 mg/wk, or placebo each for two 12-week periods. There was significant improvement of pulmonary function and reduction of prednisone requirement in both placebo and methotrexate treatment periods. However, methotrexate was not superior to placebo. Only 3 of 11 patients responded to methotrexate. Although low-dose methotrexate therapy may have a role in a small select group of steroid-dependent asthmatics, it provided no additional benefit overall.

Is asthma curable?

The information reviewed here supports the concept that asthma is potentially curable. Reports of complete, durable remission of asthma can no longer be regarded as fortuitous occurrences, unrepresentative of asthma in general. Systematic studies of anti-inflammatory drug therapy designed to explore possible induction or remission of asthma clearly are warranted. Studies of aggressive anti-inflammatory drug therapy of asthma at the onset, to avoid establishment of chronic asthma, also are desirable. The current goals of therapy of asthma have been revised to include reduction of airway hyperreactivity with topical anti-inflammatory drugs, in addition to relief of current symptoms. This approach may provide valuable resistance to exacerbations in response to antigen exposures, infections, exercise, or irritants. Pathophysiologic mechanisms apparently essential to the establishment and perpetuation of chronic asthma have been identified. These processes may be vulnerable to eradication by combination therapy with existing pharmacologic agents such as cyclosporin A or FK-506 (to suppress cytokine production), gold, methotrexate, and other anti-inflammatory drugs, alone or in combination. Equally important, the vigorous anti-inflammatory therapy may be necessary only long enough to achieve a resolution of the chronic pulmonary inflammation. Systematic studies of the use of these agents to induce partial, or complete, stable remissions of asthma should be performed. In the past, remissions of asthma in children with neoplasia and the other patients presented herein were complete, durable, and welcome, but they were largely unexpected and unpredictable. For the future, there is increasing reason to believe that predictable pharmacologically induced remission of asthma will be feasible.

Acute and chronic suppression of leukotriene B4 synthesis ex vivo in neutrophils from patients with rheumatoid arthritis beginning treatment with methotrexate

OBJECTIVE

To compare the cumulative effects of oral methotrexate (MTX) therapy (after 6-8 weeks) with the acute effects (24 hours after a dose) on arachidonic acid metabolism by the 5-lipoxygenase (5-LO) pathway in neutrophils from patients with active rheumatoid arthritis (RA) who were beginning therapy with MTX.

METHODS

Neutrophils and monocytes were isolated from whole blood from 7 patients with RA, immediately before and 24 hours after their first weekly dose of 7.5 mg of MTX, and again after their dose at 6-8 weeks.

RESULTS

Total immunoreactive leukotriene B4 (LTB4) formation in neutrophils activated ex vivo with calcium ionophore A23187 was significantly suppressed (by 33%) before the 6-8-week dose, compared with the level before the first dose (mean +/- SEM 8.29 +/- 1.24 ng/10(6) cells at predose 6-8 weeks versus 12.29 +/- 2.13 ng/10(6) cells at predose 1; P = 0.03). Reductions were also observed after the first dose (27%; P = 0.07) and after the 6-8-week dose (43%; P = 0.05) compared with the respective predose levels. MTX treatment produced significant reductions in the total generation of 5-LO pathway products (5-hydroxyeicosatetraenoic acid + 6-trans-LTB4 + LTB4 + omega-oxidation products of LTB4) by calcium ionophore-activated neutrophils, as quantitated by integrated optical density after resolution on reverse-phase high-performance liquid chromatography. Decreases were observed after the first dose (26%; P = 0.025), immediately before the 6-8-week dose (23%; P = 0.05), and after the 6-8-week dose (47%; P = 0.0033) compared with levels before the first dose, and after the 6-8-week dose compared with the level before it (32%; P = 0.04). The generation of LTB4 by calcium ionophore-activated monocytes was not significantly affected by MTX therapy.

CONCLUSION

The significant decreases in the formation of omega-oxidation products of LTB4 and in the total generation of neutrophil 5-LO pathway products in the absence of a significant change in the release of 3H-arachidonic acid or the generation of platelet-activating factor suggest that the activity of the 5-LO enzyme in neutrophils is inhibited. We conclude that weekly oral MTX therapy in patients with active RA inhibits neutrophil 5-LO pathway product generation in a pattern consistent with inhibition of the activity of the 5-LO enzyme; an effect is observed after the first dose. The inhibition of 5-LO is cell-selective and cumulative, with a superimposed incremental inhibition observed after the weekly MTX dose.

Interleukin-8 stimulates the formation of 15-hydroxy-eicosatetraenoic acid by human neutrophils in vitro

Interleukin-8 (IL-8), is a potent activator of polymorphonuclear leukocyte (PMN) functions including chemotaxis, superoxide anion production, and enzyme release and it is also chemotactic for lymphocytes. Additionally, it has recently been shown that IL-8 stimulates the formation of 5-lipoxygenase (LO) products of arachidonic acid (AA) by human PMNs. The purpose of the present study was to determine whether IL-8 also might affect the formation of 15-LO products from AA. Purified PMNs in phosphate buffered saline were preincubated with and without exogenous AA (10(-5)-10(-4) M) for 10 min. Then IL-8 was added in biologically relevant concentrations ranging from 0.1 to 100 ng/ml and incubation was carried out for 5 min at 37 degrees C. Lipids were then extracted from supernatants, and eicosanoids were determined by quantitative RP-HPLC. Compared with unstimulated cells, IL-8 resulted in a dose dependent increase in both LTB4 and 15-HETE (up to 125% and 40% at 100 ng/ml, respectively). This increase in eicosanoid formation required the presence of exogenous AA. These results indicate that IL-8 is both a potent stimulator of 5-LO activity and of 15-LO activity. LTB4 can induce both inflammation and contribute to hyperproliferation in the skin. 15-HETE in contrast has the ability to inhibit the effects induced by LTB4. Because IL-8 is able to stimulate both LTB4 and 15-HETE formation, the effect of IL-8 as a putative regulator of inflammatory processes may be dependent on the relative stimulation of 5-LO and 15-LO.

Treatment of primary biliary cirrhosis with low-dose weekly methotrexate

Nine women with symptomatic precirrhotic primary biliary cirrhosis have been treated with oral pulse methotrexate, 15 mg/wk, for 12-34 months. Three women had pruritus, two fatigue, and four pruritus and fatigue. Itching disappeared and fatigue lessened or disappeared in all within 4-11 months after starting methotrexate. All who itched were able to discontinue cholestyramine (five) or antihistamines (two). Biochemical tests of liver function improved in all patients and then worsened in three when methotrexate was discontinued or the dose lowered. Mean serum alkaline phosphatase decreased from 471 to 171 U/L (P less than 0.01), serum bilirubin from 0.99 to 0.59 mg/dL (P less than 0.05), and serum alanine aminotransferase from 132 to 61 U/L (P = 0.02), and serum cholesterol fell from 265 to 213 mg/dL (NS). The decrease in serum cholesterol was significant, P = 0.05, if data were used just from the six women whose baseline serum cholesterol levels were elevated. Serum albumin remained normal in all. The serum bilirubin levels became normal in three of four patients with elevated levels. The serum alkaline phosphatase levels became normal in four patients and the alanine aminotransferase levels in three. Liver histology improved in five patients and was stable in the remaining four based on a quantitative evaluation of coded liver biopsy specimens. The improvement in histology was primarily due to decreased portal inflammation and bile duct injury. The titer of antimitochondrial antibody decreased in seven patients. The data suggest that methotrexate may be effective treatment for precirrhotic primary biliary cirrhosis. Controlled trials are needed to evaluate long-term efficacy and toxicity.

Low-dose weekly methotrexate for unusual neutrophilic vascular reactions: cutaneous polyarteritis nodosa and Behçet's disease

Low-dose weekly methotrexate therapy has been used to treat patients with psoriasis for more than 20 years. This regimen has also been used to treat rheumatoid arthritis, inflammatory bowel disease, primary sclerosing cholangitis, and corticosteroid-dependent asthma. We report two patients with Behçet's disease with cutaneous neutrophilic vascular reactions and three with cutaneous polyarteritis nodosa who responded dramatically to low-dose weekly methotrexate therapy.

High-performance liquid chromatography method for serum methotrexate levels in children with severe steroid-dependent asthma

Monitoring of low-dose methotrexate (MTX), as used in severe steroid-dependent asthma, requires a sensitive and reproducible technique which has hitherto not been available. A high-performance liquid chromatographic method for the determination of MTX in serum is reported. The method involves deproteinization with acetone followed by addition of butanol and diethyl ether. The percentage recovery with this method compared with others was high (90 versus 70%). The samples were chromatographed on a reversed-phase ODS column and monitored at 313 nm. The retention time for MTX was 14.7 min. Pharmacokinetics of MTX was studied in five patients (age 3-15 years) with severe asthma who received a weekly oral dose of 10 mg/m2 body surface area. Following administration, the serum disappearance was monophasic with a half-life of 5 h. A metabolite, 7-hydroxymethotrexate was detected in serum after 2 h and reached a maximum concentration after 6 h. This new method will facilitate monitoring of asthmatic patients on methotrexate and allow for dose response and toxicity studies to be conducted.

Methotrexate-induced asthma

A patient with rheumatoid arthritis developed pulmonary symptoms and function test abnormalities consistent with asthma during methotrexate therapy. Assessments of airway responsiveness to methacholine during therapy revealed airway hyperreactivity that reverted to normal when the methotrexate was stopped. An extension of the methotrexate dosage interval from 7 to 10 days resulted in an abolition of the asthma, which remained in remission despite a return to a weekly cycle after a 3-month period of 10-day cycles.

Methotrexate: mechanism of action in rheumatoid arthritis

Most studies of immune function in rheumatoid arthritis (RA) patients treated with methotrexate (MTX) show only marginal effects on humoral or cellular immune responses. These include measurements of lymphocyte subsets, proliferative responses to mitogens, immunoglobulin production, rheumatoid factor and immune complexes. The mechanism of action of MTX in RA might be more antiinflammatory than immunosuppressive. This is supported by the rapid clinical response to drug treatment and by data from in vitro and animal studies. The inhibition of interleukin-1 (IL-1) activity or other inflammatory cytokines by MTX may play an important role in the antiinflammatory effect of MTX. MTX effects in RA are not fully understood and further studies are needed to clarify its mechanism of action. MTX has crucial effects on the cascade of events initiated by some cytokines (IL-1, IL-6, tumor necrosis factor), which plays a major role in RA and other inflammatory diseases.

Cytotoxic and Immunologic Effects of Methotrexate in Psoriasis

Based on recent experience that Cyclosporin A, an immunosuppressive drug, produces marked improvement in psoriasis, possible immunomodulatory activities of methotrexate (MTX) have been reviewed to look for alternate mechanisms of MTX action in psoriasis. It is generally considered that the therapeutic results of MTX in psoriasis are related to a direct effect on epidermal cell hyperplasia through inhibition of DNA synthesis. Several studies in the literature now suggest possible effects of MTX on the immune system of psoriatics as well as in animal models that may have some pathogenic similarities to psoriasis. In psoriatics receiving MTX, neutrophil chemotaxis is suppressed, resulting in a possible alteration in the potential pathologic activity of neutrophils commonly found in lesional skin. MTX does improve both psoriatic and rheumatoid arthritis. Animal studies of the latter using adjuvant arthritis and graft vs host disease (GVHD) have indicated several possible mechanisms for MTX that affect these processes. In GVHD, MTX selectively destroys cycling CD8+ cells, and in adjuvant arthritis the activation of macrophages is prevented by inhibition of T-cell function. While MTX generally has not been clinically utilized as an immunomodulatory drug for immunologically related diseases, it may, nonetheless, have selective actions that could be specific for some diseases. MTX and Cyclosporin A could work mechanistically in similar ways but at different steps in the activation of T cells and macrophages. It may be that the major direct effect of MTX on epidermal cell proliferation is complemented or even mediated by subtle immunoregulatory effects on the melange of cells in the affected skin and the systemic immune response.

Inhibition of leukotriene B4 synthesis in neutrophils from patients with rheumatoid arthritis by a single oral dose of methotrexate

We studied the effects of a single, oral dose of methotrexate (MTX) on arachidonic acid metabolism in neutrophils from 6 patients with rheumatoid arthritis, which were obtained 1 day before and 1 day after their usual weekly MTX dose. The 6 patients had received a mean weekly MTX dose of 9.6 mg (range 5-15) for a mean of 61.7 months (range 58-64), and none received concomitant corticosteroids. Total generation of leukotriene B4 (LTB4) in neutrophils stimulated ex vivo with 10 microM calcium ionophore A23187 for 20 minutes was significantly suppressed, by a mean of 53%, after the MTX dose compared with the predose levels (mean +/- SEM 13.0 +/- 1.4 ng/10(6) cells versus 6.0 +/- 0.9 ng/10(6) cells; P = 0.0019), reflecting a comparable suppression of both released and cell-retained LTB4. A 49% decrease in omega-oxidation products of LTB4 demonstrates that decreased LTB4 synthesis, rather than increased degradation, is responsible for the decrease in LTB4 generation. The absence of a significant change in either 3H-labeled arachidonic acid release or platelet-activating factor generation indicates that the observed decrease in LTB4 synthesis was apparently not caused by diminished phospholipase A2 activity. A 28% decrease in the total formation of the 5-lipoxygenase products 5-hydroxyeicosatetraenoic acid and the 6-trans-LTB4 diastereoisomers, and a 48% suppression of production of LTB4 plus its omega-oxidation metabolites after the MTX dose suggest inhibition of 5-lipoxygenase activity and possible suppression of leukotriene A4 epoxide hydrolase activity.

15-hydroxyeicosatetraenoic acid (15-HETE) specifically inhibits the LTB4-induced skin response

15-Hydroxyeicosatetraenoic acid (15-HETE), a 15-lipoxygenase product of arachidonic acid, inhibits leukotriene B4 (LTB4)-induced chemotaxis of polymorphonuclear leukocytes (PMNs) in vitro. In this study the effects of intradermal injections of LTB4 were determined in the absence or presence of 15-HETE. For comparison intradermal injections of purified human complement split product C5a were performed in the absence or presence of 15-HETE. The skin response was evaluated by measuring the diameter of the wheal, the area of the flare and by intensity of the erythema (erythema index). LTB4 and C5a were injected at the concentration of 200 ng/ml. At this concentration the maximal skin response of LTB4 and C5a were equivalent. In contrast to C5a reaction, which resolved within 1 h, LTB4-induced skin response lasted up to 18 h. In all subjects the skin response was significantly decreased when LTB4 was injected together with 300 ng of 15-HETE. The decrease of wheal, flare, and erythema index averaged 81.9%, 56.6%, 53.6%, respectively, when all parameters were obtained at the maximal skin response. In contrast, the C5a-induced skin response was not affected by addition of 15-HETE, even when the final dose of 15-HETE was increased 10 times to 3 micrograms. The LTB4-induced reaction could last up to 18 h after injection. After the addition of 300 ng of 15-HETE the skin response resolved after 1 h. The present results demonstrate that 15-HETE is a specific inhibitor of the LTB4-induced skin response and brings additional evidence in support of the ability of 15-HETE to regulate the proinflammatory effects of LTB4 in vivo.

Eicosanoids in acute and chronic psoriatic lesions: leukotriene B4, but not 12-hydroxy-eicosatetraenoic acid, is present in biologically active amounts in acute guttate lesions

The biochemical changes underlying the clinical manifestations of psoriasis are unknown. Certain chemotactic eicosanoids derived from arachidonic acid metabolism have been suggested to play important roles in psoriasis, because of their presence in lesional psoriatic skin and their ability to elicit skin inflammation and to stimulate epidermal proliferation. The purpose of the present study was to elucidate which eicosanoids might be involved in the early phases of the inflammatory processes of psoriasis. Eicosanoids were analyzed in scale and in lesional skin without scale both in acute guttate and chronic plaque psoriatic lesions. Methods for identification of eicosanoids included reversed-phase high-performance liquid chromatography combined with radioimmunoassay. Leukotriene B4 was present in both acute guttate and chronic plaque skin lesions in biologically active amounts (acute guttate lesions: 18.7 +/- 7.1 ng/g wet tissue in scale and 3.2 +/- 1.5 ng/g wet tissue in lesional skin without scale; chronic plaque lesions: 33.1 +/- 9.7 ng/g wet tissue in scale and 5.3 +/- 2.0 ng/g wet tissue in lesional skin without scale). 12- and 15-hydroxy-eicosatetraenoic acid (HETE) reached biologically active concentrations only in scale of chronic plaque lesions (1,512 +/- 282 and 1,441 +/- 411 ng/g wet tissue, respectively). The level of prostaglandin E2 in chronic plaque lesions was similar to the level in normal skin, while the level in acute guttate lesions was increased twofold (71.0 +/- 14.8 ng/g wet tissue). These results demonstrate that leukotriene B4, but not 12-HETE, is present in acute guttate psoriatic skin lesions in concentrations able to exert biologic effects. Leukotriene B4 may therefore participate in inflammatory changes of acute psoriasis.

Transendothelial cell diapedesis of neutrophils in inflamed human skin

The mode of extravasation of neutrophils (PMNs) in cutaneous inflammation was studied in sequential biopsy specimens taken from human skin. Inflammatory skin reactions were produced by intracutaneous injection of endogeneous mediators of inflammation--C5ades arg, LTB4, neutrophil-activating peptide (NAP) and interleukin-1 (IL-1). Within 30 min after injection neutrophils were observed in close contact with endothelial cells of postcapillary venules and, following cytoplasmic engulfment, the cells were found to be transported transcellulary through the endothelial layer. In a total of 20 biopsy specimens taken at various times, cell migration via interendothelial gaps was absent. Instead, the transcellular pathway appeared to be the first and foremost mode of diapedesis. During this migratory process PMNs lacked signs of degranulation and numerous electron-lucent vesicles and secondary lysosomes were found. In addition, coated pits present on leukocyte as well as endothelial-cell membranes were indicative of receptor-mediated endocytotic processes.

Methotrexate in the treatment of corticosteroid-dependent asthma. A double-blind crossover study

To test our previous observation that methotrexate reduces corticosteroid requirements of patients with severe asthma, we studied 14 patients with corticosteroid-dependent bronchial asthma in a 24-week randomized double-blind crossover trial comparing a low dosage of methotrexate (15 mg per week) with placebo. At base line the mean dosage of prednisone was 173.5 mg per week (range, 70 to 420). On the average, 36.5 percent less prednisone was required when patients received methotrexate than when they received placebo (P = 0.01). Measurement of forced vital capacity and forced expiratory volume in one second showed that there was no deterioration in the condition of patients in whom the dosage of prednisone was reduced. The patients' subjective assessment of breathing ability indicated significant improvement (P = 0.01). The adverse effects of methotrexate were limited to transient nausea in three patients and an evanescent rash in one patient. Nine patients are still receiving methotrexate 3 to 10 months after the study's conclusion. The dosages of steroids have been further reduced in each of these patients, and prednisone has been discontinued in four. We conclude from this preliminary study that the use of methotrexate allows a significant reduction in the use of corticosteroids in patients with severe asthma without deterioration of pulmonary function.