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

Effects of polysaccharide fractions isolated from Caltha palustris L. on the activity of phagocytic cells & humoral immune response in mice with collagen-induced arthritis: A comparison with methotrexate

BACKGROUND & OBJECTIVES

The extracts from Caltha palustris L. have been shown to be beneficial for treating arthritis and rheumatism. In this study, the immunomodulatory effects of polysaccharide fractions B and C of C. palustris extracts were studied, using the collagen-induced arthritis (CIA) mouse arthritis experimental model. The aim was to determine the activity of blood phagocytic cells and humoral immune response in CIA mice treated with polysaccharide fractions from C. palustris.

METHODS

The effects of fractions B and C of C. palustris were explored by evaluating phagocytic activity of peripheral blood granulocytes and monocytes and humoral immune response in sheep red blood cell (SRBC)-immunized mice. The results were compared with methotrexate (MTX) treatment. Following the onset of CIA, DBA/1J mice were treated for 21 days with B or C fractions (10 mg/kg; i.p.) or MTX (every 48 h, 6.6 mg/kg; i.p.).

RESULTS

The results showed that fraction B reduced the level of interleukin (IL)-1β, boosted nitric oxide synthesis in murine peritoneal macrophages stimulated in vitro with lipopolysaccharide and enhanced the monocyte phagocytic activity. Exposure of SRBC-immunized mice to fraction B and MTX during the course of CIA resulted in decreased total anti-SRBC haemagglutinin titres.

INTERPRETATION & CONCLUSIONS

Fraction B of C. palustris polysaccharides modulated macrophage function and exerted beneficial effects on the clinical course of CIA in mice. The results also suggested efficacy of fraction B was comparable to that of MTX treatment for certain parameters.

Impact of methotrexate on oxidative stress and apoptosis markers in psoriatic patients

Methotrexate (MTX), a cytotoxic chemotherapeutic agent, is considered an effective drug in the treatment of psoriasis. The aim of this study was to find out whether the effect of MTX treatment in psoriasis is due to oxidative stress-induced apoptosis. Psoriasis vulgaris patients (58 in number) were recruited for this study. Healthy volunteers (45 in number) served as control. Samples of psoriatic patients were collected and analyzed for total reactive oxygen species (ROS), malondialdehyde (MDA) levels, nitrite, nitrate levels and the activities of antioxidants like superoxide dismutase (SOD), catalase (CAT) and total antioxidant status (TAS) and also the protein expression of caspase-3, before (Day 0) and after (at the end of 6 and 12 weeks) MTX treatment. Our results show a significant increase in tissue ROS and plasma MDA after MTX treatment when compared with before MTX treatment in psoriasis patients (p < 0.001). The levels of serum nitrite and nitrate were decreased significantly after MTX treatment (p < 0.001). The activities of plasma SOD, TAS and serum CAT levels were decreased, but not significantly after 12 weeks of treatment. The expression of caspase-3 was increased after MTX treatment. In conclusion, MTX induce apoptosis through oxidative stress by reducing NO and increasing caspase-3 levels. MTX-induced apoptosis may account for the beneficial effect of MTX treatment in psoriasis patients, which is characterized by acanthosis.

Nitric oxide levels in patients with psoriasis treated with methotrexate

Psoriasis is a chronic, recurrent, inflammatory, and hyperproliferative disease. Recently there have been studies regarding increases in the levels of NO in inflammatory dermatoses including psoriasis. In this study, 22 patients with psoriasis were scored with PASI (psoriasis area and severity index) and the levels of serum nitrite-nitrate were evaluated before and after therapy with methotrexate (Mtx). The results were compared with age- and sex-matched healthy volunteers. The relation of the results with the clinical severity and the cumulative Mtx dose were also evaluated. The serum levels of nitrite-nitrate of the psoriatic patients with active lesions were found to be significantly higher than the levels of the healthy volunteers and the patients after therapy. The elevated nitrite-nitrate serum levels in the inflammatory period may suggest the possible role of this mediator in the etiopathogenesis of psoriasis and the potential future use of No inhibitors in the treatment of psoriasis.

Combination treatment of rat adjuvant-induced arthritis with methotrexate, probiotic bacteria Enterococcus faecium, and selenium

The effects of the probiotic bacteria Enterococcus faecium (EF) and selenium were studied on methotrexate (MTX) treatment in rats with adjuvant arthritis. Arthritic rats were treated orally with the following substances: lyophilized EF (15 mg/kg/day, 5 days a week), sodium selenite pentahydrate (SSe; 0.050 mg/kg containing 0.015 mg/kg selenium, 5 days a week), MTX (0.6 mg/kg/week), and their combinations for the period of 50 days from adjuvant application. Levels of serum albumin, serum nitrite/nitrate concentrations, hind paw swelling, arthrogram scores, whole-body bone mineral density (BMD), and bone erosions were evaluated as markers of inflammation and destructive changes associated with arthritis. Long-term preventive treatment with low-dose MTX significantly inhibited the markers of both inflammation and arthritis. EF or SSe when administered singly or in combination had no significant effect on the given parameters in arthritic rats. EF, but not SSe, potentiated the beneficial effects of MTX, which resulted in a more significant reduction of hind paw swelling, arthrogram scores, and whole-body BMD decrease. EF also had a tendency to improve the effect of MTX on serum albumin and nitrite/nitrate concentrations. Our results indicate that EF may increase the preventive effect of MTX treatment in rat adjuvant arthritis by improving its anti-inflammatory and antiarthritic effects.

Effects of methotrexate upon inflammatory parameters induced by carrageenan in the mouse model of pleurisy

BACKGROUND

The model of pleurisy induced by carrageenan exhibits a biphasic response (4 and 48 h) and permits the quantification of exudate, cell migration and certain enzymes such as myeloperoxidase (MPO) and adenosine-deaminase (ADA) that are markers of activated leukocytes.

AIMS

The present study evaluates whether there exists, in the pleurisy model, a significant inhibition of ADA and MPO enzymes, leukocyte kinetics and other markers of inflammation [nitric oxide (NO) levels, exudation] caused by methotrexate treatment by the intraperitoneal (i.p.) route.

METHODS

The pleurisy was induced by carrageenan (1%) in mice, and the parameters were analyzed 4 and 48 h after.

RESULTS

After the induction of inflammation (4 h), methotrexate (20 mg/kg, i.p., 24 h before pleurisy induction) inhibited the leukocyte infiltration (p < 0.05), NO levels and MPO activity (p < 0.01), but not ADA activity and fluid leakage (p > 0.05). Regarding the second phase of pleurisy (48 h), methotrexate (40 mg/kg, i.p., 0.5 h before pleurisy induction) inhibited the leukocyte infiltration (p < 0.05), fluid leakage, NO levels (p < 0.01), and ADA and MPO activity (p < 0.05).

CONCLUSIONS

These findings support the evidence that the acute administration of methotrexate has an important systemic anti-inflammatory activity in the studied inflammatory model. This effect was due to a significant inhibition on both neutrophil and mononuclear cells, being less marked in relation to exudation 48 h after. In relation to the enzymes studied and to NO levels, the findings support the evidence that methotrexate inhibits both enzymes (MPO and ADA) from leukocytes at the site of injury, thus reflecting the activation of both neutrophils and lymphocytes, respectively. Furthermore, the inhibiting effect on NO in both phases of pleurisy induced by carrageenan (4 and 48 h) indicates that methotrexate acts on constitutive and/or inducible NO synthases by means of different cells of the pleural cavity.

Calcineurin inhibitors, cyclosporin A and tacrolimus inhibit expression of inducible nitric oxide synthase in colon epithelial and macrophage cell lines

Nitric oxide (NO) production is increased in inflammatory bowel disease and selective inducible nitric oxide synthase (iNOS) inhibitors have proved to be anti-inflammatory in experimentally induced colitis. The aim of the present study was to test if drugs used in the treatment of inflammatory bowel disease effect on NO production in colon epithelial and macrophage cell lines. We tested the effects of cyclosporin A, tacrolimus (FK-506), methotrexate, sulfasalazine, 5-aminosalicylic acid and two novel TNF-alpha antagonists etanercept and infliximab on endotoxin-induced NO production in human T84 colon epithelial cells and in murine J774 macrophages. Cyclosporin A and FK-506 inhibited iNOS expression, and subsequent NO production, in a dose-dependent manner at therapeutically achievable drug concentrations in both cell lines. The effect was most pronounced when cyclosporin A was given 1 h prior to 4 h after endotoxin, and declined thereafter, indicating that cyclosporin A does not inhibit iNOS activity. Neither cyclosporin A nor FK-506 altered the activation of nuclear factor-kappaB (NF-kappaB) that is a critical transcription factor for iNOS. Sulfasalazine inhibited NO production slightly only when given at high (100 microM) drug concentrations. Methotrexate, 5-aminosalicylic acid and TNF-alpha antagonists infliximab and etanercept were practically ineffective. Two inhibitors of phosphatase calcineurin, cyclosporin A and FK-506, inhibited iNOS expression and NO production in human T84 colon epithelial cells and in murine J774 macrophages by an NF-kappaB independent manner. These findings are implicated in the anti-inflammatory action of these compounds.

Treatment of experimental adjuvant arthritis with the combination of methotrexate and lyophilized Enterococcus faecium enriched with organic selenium

The efficacy of combination therapy with methotrexate (MTX) and probiotic bacteria Enterococcus faecium enriched with organic selenium (EFSe) in rats with adjuvant arthritis was determined. Rats with adjuvant arthritis were given MTX (0.3 mg/kg 2-times weekly, orally); lyophilized E. faecium enriched with Se (15 mg/kg, 5 d per week, orally); and a combination of MTX plus EFSe for a period of 50 d from the immunization. Levels of serum albumin, serum nitrite/nitrate concentrations, changes in hind paw swelling, arthrogram score, bone erosions, whole body bone mineral density (BMD) and bone mineral content (BMC) were assayed in the rats as variables of inflammation and destructive arthritis-associated changes. Treatment with MTX and with the combination MTX + EFSe significantly inhibited markers of both inflammation and arthritis. Significant differences in favor of combination therapy with MTX + EFSe as compared to MTX alone were seen in serum albumin concentration, hind paw swelling and arthrogram score. Reductions in radiographic scores were also more pronounced in the combination therapy group. Combination therapy, but not MTX alone, inhibited the reduction of BMD and BMC; treatment with lyophilized EFSe alone had no significant effect on adjuvant arthritis in rats. The potent therapeutic effect of low dosage MTX therapy in combination with lyophilized EFSe on adjuvant arthritis in rats was shown.

Low levels of nitric oxide (NO) in systemic sclerosis: inducible NO synthase production is decreased in cultured peripheral blood monocyte/macrophage cells

OBJECTIVE

To investigate nitric oxide (NO) production and inducible NO synthase expression by cultured peripheral blood mononuclear cells (PBMC) in patients with systemic sclerosis (SSc).

METHODS

Eighteen patients with SSc were compared with two control groups: 16 patients with rheumatoid arthritis (RA) and 23 patients with mechanical sciatica. Nitrate was determined by fluorimetry in plasma and by spectrophotometry in supernatants. Inducible NO synthase (iNOS) was detected in cultured PBMC by immunofluorescence, immunoblotting and flow cytometry with or without treatment of the cells with interleukin (IL) 1beta+ tumour necrosis factor alpha (TNF-alpha), IL-4 or interferon gamma (IFN-gamma) from day 1 to day 5.

RESULTS

NO metabolite concentrations were lower in SSc patients (mean+/-s.e.m. 34.3+/-2.63 micromol/l) than in RA (48.3+/-2.82 micromol/l; P<0.02) and sciatica (43.3+/-5.24 micromol/l; P<0.03) patients. iNOS was detected in cultured monocytes in all three groups but induction occurred on day 1 in RA, day 2 in sciatica and only on day 3 in SSc, whatever the stimulus.

CONCLUSIONS

The concentrations of NO metabolites are decreased in SSc patients and the metabolism of these compounds in PBMC is altered. Low levels of NO, a vasodilator, may be involved in vasospasm, which is critical in SSc. This may have therapeutic implications.