In vitro immunomodulatory effects of sulfasalazine and its metabolites

We assessed the in vitro effects of sulfasalazine and its 2 main metabolites, sulfapyridine (SP) and 5-aminosalicylic acid (5-ASA) on functional aspects of peripheral blood lymphocytes (PBM) of normal controls and patients with rheumatoid arthritis (RA). Sulfasalazine, but not its 2 main metabolites, inhibited mitogen induced proliferative responses of PMB at high drug concentrations (100 micrograms/ml). Similar results were obtained with purified B lymphocytes. Sulfasalazine depressed, in a dose dependent manner, pokeweed mitogen induced Ig synthesis by PBM of normals and patients with RA. Moreover, synthesis of IgM rheumatoid factor was depressed to a greater degree than total IgM at low sulfasalazine concentrations (10-25 micrograms/ml). Both SP and 5-ASA were not inhibitory at the concentrations tested. Experiments with purified lymphocyte subpopulations indicated that sulfasalazine exerted its major inhibitory activity on the B lymphocyte. These studies indicate that sulfasalazine, but not its 2 main metabolites, has immunomodulatory characteristics which may be related to its therapeutic activity in RA.

Sulfasalazine treatment and lymphocyte function in patients with rheumatoid arthritis

Sulfasalazine is now an established 2nd line agent in the treatment of rheumatoid arthritis (RA) but its mode of action is unknown. Two separate studies have investigated the possibility that it works in RA by influencing lymphocyte function. After 12 weeks of treatment with sulfasalazine, elevated levels of circulating activated lymphocytes and abnormal ex vivo mitogen response to concanavalin A (Con-A) in 11 patients with RA reverted to normal. An in vitro study investigated the effect of sulfasalazine and its metabolites on mitogen response by healthy and RA peripheral blood mononuclear cells (PBMC). Sulfapyridine (SP) and 5-hydroxy SP suppressed the response of RA PBMC to Con-A. Sulfasalazine, SP and N-acetyl SP suppressed the response of healthy PBMC to pokeweed mitogen. 5-aminosalicylic acid also affected mitogen response and cell viability, which may be relevant to actions of this metabolite within the gut.

The scavenging of oxidants by sulphasalazine and its metabolites. A possible contribution to their anti-inflammatory effects?

Sulphasalazine (Salazopyrin) and its metabolites sulphapyridine and 5-aminosalicylate are powerful scavengers of the hydroxyl radical, determined by pulse radiolysis and confirmed by assays based on deoxyribose degradation by hydroxyl radicals. 5-Aminosalicylate can also protect alpha 1-antiprotease against attack by the myeloperoxidase-derived oxidant hypochlorous acid. The ability to scavenge oxidants produced at sites of inflammation may contribute to the anti-inflammatory action of sulphasalazine and its metabolites.

Inhibition of neutrophil degranulation and superoxide production by sulfasalazine. Comparison with 5-aminosalicylic acid, sulfapyridine and olsalazine

Sulfasalazine is a potent inhibitor of superoxide production and granule enzyme release by stimulated neutrophils, and modulation of these responses may contribute to its anti-inflammatory properties. It is a composite drug consisting of 5-aminosalicylic acid and sulfapyridine joined through an azo linkage. To investigate which functional groups on the molecule are active against neutrophil responses, 5-aminosalicylic acid, sulfapyridine and olsalazine were added to cells stimulated with fMet-Leu-Phe or immune complexes. The inhibitory effects of sulfasalazine on superoxide production, degranulation and neutrophil-mediated collagen degradation were closely mimicked by olsalazine, with the other two compounds having little effect on either function. Thus the azo link appears to be the important structural feature of sulfasalazine that affects neutrophil responses. This suggests that sulfasalazine could be anti-inflammatory in its own right rather than just acting as a source of 5-aminosalicylic acid. Our findings are also a favourable indication for olsalazine (Dipentum), which is currently under trial as an anti-inflammatory agent.

Actions of sulfasalazine and 5-aminosalicylic acid as reactive oxygen scavengers in the suppression of bile acid-induced increases in colonic epithelial cell loss and proliferative activity

Sulfasalazine suppresses mucosal injury in patients with ulcerative colitis, but the mechanism of its therapeutic action is uncertain. In the present study, we examined the mechanism of the protective action of sulfasalazine in a rat model in which colonic epithelial cell loss and subsequent increases in epithelial proliferative activity were induced by intracolonic instillation of sodium deoxycholate. Sulfasalazine or its therapeutically active metabolite 5-aminosalicylic acid suppressed the loss of deoxyribonucleic acid into the colonic lumen and the subsequent increases in mucosal ornithine decarboxylase activity and tritiated thymidine incorporation into deoxyribonucleic acid induced by sodium deoxycholate. Sulfasalazine and 5-aminosalicylic acid also blocked xanthine-xanthine oxidase-induced loss of deoxyribonucleic acid and the subsequent proliferative response. In vitro sodium deoxycholate increased reactive oxygen formation by colonic mucosal scrapings or isolated crypt epithelium. These actions of sodium deoxycholate on reactive oxygen formation were blocked by sulfasalazine or 5-aminosalicylic acid. Sulfapyridine, a therapeutically inactive metabolite of sulfasalazine, had no effect on sodium deoxycholate-induced increases in surface cell sloughing, ornithine decarboxylase, tritiated thymidine incorporation into deoxyribonucleic acid, chemiluminescence, or superoxide production. The ability of sulfasalazine and 5-aminosalicylic acid to scavenge reactive oxygen may play a role in their therapeutic effects of inflammatory bowel disease.

Effect of sulphasalazine and its metabolites on the generation of reactive oxygen species

The relative in vitro anti-oxidant efficacy of sulphasalazine (salicylazosulphapyridine, SASP) and its metabolites (5-aminosalicylic acid, 5-ASA; sulphapyridine, SP) was examined by studying their effects on the generation of reactive oxygen species (ROS) using zymosan-stimulated polymorphonuclear leucocytes (PMNs) and a cell free, xanthine-xanthine oxidase system. Salicylazosulphapyridine, 5-ASA, and SP showed anti-oxidant effects to the various degrees. In particular, production of OH, which is one of the most potent reactive oxygen species, was remarkably suppressed by 5-ASA dose relatedly. These findings suggest that SASP and its metabolites play an important role in the inhibition of respiratory bursts. As the potent products of the respiratory burst by polymorphonuclear leucocytes are thought to be important inflammatory mediators, suppression of toxic reactive oxygen species generation by these agents may partly explain the therapeutic efficacy of SASP in ulcerative colitis, which is characterised by an acute mucosal inflammation dominated by polymorphonuclear leucocytes accumulation.

Azodisalicylate (azodisal sodium) causes intestinal secretion. Comparative study of the effect of azodisalicylate, sulfasalazine, 5-aminosalicylic acid and sulfapyridine on the water and electrolyte transfer and the morphology of the rat ileum and colon in vivo

Azodisalicylate (ADS) is one of the possible successors of sulfasalazine in the treatment of ulcerative colitis. The following results were obtained when comparing the influence of ADS on net water and electrolyte transfer in tied-off loops of the rat ileum and colon in vivo with sulfsalazine, 5-aminosalicylic acid, and sulfapyridine. (1) Sulfasalazine, 5-aminosalicylic acid and sulfapyridine had no effect on water and electrolyte transfer of the healthy intestinal mucosa in concentrations up to 400 mg%. (2) ADS showed a concentration-dependent inhibition effect on net water, sodium and chloride absorption and stimulated secretion at concentrations higher than 100 mg%. (3) No morphological alterations of the mucosa could be observed by light and transmission electron microscopy. The observed effect of ADS might have some clinical significance in patients with a decreased absorptive capacity of the colon in ulcerative colitis, in contrast to healthy volunteers, where the high absorptive capacity of the colon might compensate the decreased absorption or stimulated secretion in the small intestine.

Inhibition of cytotoxicity by sulfasalazine. II. Sulfasalazine and sulfapyridine inhibit different stages of the NK and NKCF lytic processes

Sulfasalazine and sulfapyridine but not 5-aminosalicylate inhibit spontaneous cytotoxicity mediated by human natural killer (NK) cells. The aim of this study was to determine which stage(s) of the NK cytotoxic reaction is inhibited by these compounds. Effector/target cell binding studies performed in parallel with cytotoxicity assays using purified large granular lymphocytes indicated that inhibition is a post-binding event. The kinetic profile of inhibition in a calcium pulse assay showed that inhibition continues long after the effector cell triggering stage and that although sulfasalazine may have some inhibitory effect on the calcium-dependent events of the programming phase, sulfapyridine continues to inhibit during the calcium-independent or lethal hit phase of the cytotoxic sequence. The NK soluble cytotoxic factor (NKCF) assay was used as a measure of the lethal hit since the time course of this assay permits study of the various substages of this terminal event in the lytic sequence. Sulfasalazine and sulfapyridine but not 5-aminosalicylate inhibited NKCF-mediated target cell lysis. Different substages of the NKCF-induced lytic reaction were affected by these agents. Sulfasalazine appears to inhibit binding of NKCF to the target cell whereas sulfapyridine predominantly inhibits early post-binding events.

Inhibition of cytotoxicity by sulfasalazine. I. Sulfasalazine inhibits spontaneous cell-mediated cytotoxicity by peripheral blood and intestinal mononuclear cells from control and inflammatory bowel disease patients

We have studied the effects of sulfasalazine and its metabolites on cell-mediated cytotoxicity by peripheral blood and intestinal mononuclear cells from both control and inflammatory bowel disease (IBD) patients. Sulfasalazine and sulfapyridine, as well as hydrocortisone and nordihydroguaiaretic acid inhibited spontaneous cell-mediated cytotoxicity by control and IBD peripheral blood cells. Sulfasalazine and nordihydroguaiaretic acid inhibited spontaneous cell-mediated cytotoxicity by control and IBD intestinal mononuclear cells cultured for 72 h in media alone. In contrast, 5-aminosalicylate, indomethacin and benzylimidazole had no effect on cytotoxicity by any cell population. Lectin-induced, antibody-dependent and interleukin-2-induced cell-mediated cytotoxicity, as well as lymphokine-activated killing were not inhibited by the drugs: inhibitory effects in these assays were primarily upon the underlying spontaneous cell-mediated cytotoxicity. The inhibition induced by sulfasalazine, sulfapyridine and nordihydroguaiaretic acid could not be reversed by adding the lipoxygenase metabolites leukotriene B4 or 12-hydroxyeicosatetraenoic acid. These findings demonstrate that spontaneous cell-mediated cytotoxicity by control and IBD mononuclear cells can be inhibited by sulfasalazine.

Effect of 5-aminosalicylic acid (5-ASA) and other salicylates on short-chain fat metabolism in the colonic mucosa. Pharmacological implications for ulcerative colitis

5-Aminosalicylic acid (5-ASA) suppressed nitrite-stimulated oxidation of the fatty acid n-butyrate in a dose-dependent manner in isolated human and rat colonic epithelial cells. 4-ASA had one-sixth of the capacity of 5-ASA and sulphapyridine (SP) little of the capacity of 5-ASA to suppress fatty acid oxidation in human colonic epithelial cells. Sulphasalazine (SASP), azodisalicylic acid (ADS), acetyl-5-ASA and acetyl salicylic acid (ASA) did not suppress fatty acid oxidation in rat colonocytes. The suppression index of fatty acid oxidation (SIFO) of respective salicylic acids correlated with the reported clinical effectiveness of each drug against ulcerative colitis (UC). The capacity of 5-ASA to affect nitrite-stimulated oxidation of fat in the colonic mucosa suggests that nitrite ions and control of fatty acid oxidation play a central role in the development and therapy of active UC.

Modulation of human colonic arachidonic acid metabolism by sulfasalazine

The effects of sulfasalazine and its moieties on synthesis of individual products of arachidonic acid metabolism by human colonic mucosa have been investigated. Sulfasalazine inhibited synthesis of the lipoxygenase products. Sulfasalazine and sulfapyridine also inhibited synthesis of thromboxane B2 while enhancing synthesis of prostaglandin (PG) F2 alpha or PGE2, respectively. Inhibition of synthesis of lipoxygenase products and modulation of the profile of cyclooxygenase products could reduce inflammation and enhance mucosal resistance to damage in ulcerative colitis.

Sulphasalazine and derivatives, natural killer activity and ulcerative colitis

The effects of sulphasalazine, 5-aminosalicylic acid (5-ASA), sulphapyridine and azodisalicylic acid (ADS) in vitro on the natural killer (NK) activity of peripheral blood mononuclear cells (MNC) have been examined and compared with those of the lipoxygenase inhibitor, nordihydroguaiaretic acid (NDGA) and the cyclooxygenase inhibitor, indomethacin. Sulphasalazine, sulphapyridine and ADS inhibited NK activity with 50% inhibitory concentrations (IC50) of 0.7, 2.5 and 4.0 mmol/l respectively. The effect was rapidly reversible. In contrast, 5-ASA minimally inhibited NK activity at 50 mmol/l only. NDGA potently inhibited NK activity (IC50 27 mumol/l) but this was only partly reversible in short term incubations. Indomethacin had no effect at concentrations less than those inhibiting cyclo-oxygenase activity (1-10 mumol/l) but potently and reversibly inhibited NK activity at or above 25 mumol/l. The inhibitory effects observed were unlikely to be due to direct toxicity of effector cells as 5-ASA, sulphapyridine and ADS had no effect on the viability of peripheral blood MNC, whereas NDGA and indomethacin lysed MNC only at maximal concentrations tested. Though sulphasalazine produced MNC lysis at and above 1 mmol/l, the rapid reversibility of the inhibition of NK activity at 1 mmol/l suggested that lysis of NK cells contributed little to the suppressive effect at this concentration. The disparity of the therapeutic efficacy and effects on NK activity of sulphasalazine and its derivatives in vitro may suggest that NK activity is not a major pathogenic mechanism in ulcerative colitis. Any inhibitory effect on cellular immune function of indomethacin does not necessarily reflect an effect of cyclo-oxygenase inhibition.

Influence of sulfasalazine, 5-aminosalicylic acid and sulfapyridine on prostanoid synthesis and metabolism in rabbit colonic mucosa

The effects of sulfasalazine (SASP) and its cleavage products 5-aminosalicylic acid (5-ASA) and sulfapyridine (SP) on prostanoid (PG) synthesis and degradation were determined in rabbit colonic mucosa fractions in vitro. When the microsomal fraction was incubated with (14C)arachidonic acid, 10(-3) M SASP and SP did not markedly change the formation of labeled PGE2, PGF2 alpha, TxB2 and 6-keto-PGF1 alpha X 10(-4) M 5-ASA increased synthesis about 2.7-fold; the pattern of PG identified was unaltered. In the presence of the 10-fold higher concentration of 5-ASA, PG synthesis remained elevated at a similar level. When the cytosolic fraction was incubated with (3H)PGE2, 10(-3) M 5-ASA was without influence and 10(-3) M SP decreased slightly PGE2 breakdown. However, SASP showed a pronounced inhibitory effect at 10(-5) M and inhibition of PGE2 degradation was complete at 10(-3) M SASP. The results are compatible with the assumption that stimulation of PG synthesis by 5-ASA is related to therapeutic benefit in the treatment of ulcerative colitis.

Soybean lipoxygenase inhibition: studies with the sulphasalazine metabolites N-acetylaminosalicylic acid, 5-aminosalicylic acid and sulphapyridine

Soybean lipoxygenase inhibition has been proposed as an in vitro biochemical model for the antiinflammatory action of certain drugs used in the treatment of ulcerative colitis. In an extension of a recent study which showed that therapeutically active compounds, such as sulphasalazine and its colonic metabolite 5-aminosalicylic acid were soybean lipoxygenase inhibitors, it has now been shown that N-acetylaminosalicylic acid, the principal metabolite of 5-aminosalicylic acid, also inhibits soybean lipoxygenase in a dose dependent and noncompetitive manner (Ki 3.0 X 10(-8) M, IC50 250 microM). Sulphapyridine, the other major metabolite of sulphasalazine, which has been demonstrated to be inactive in the treatment of ulcerative colitis, did not inhibit the lipoxygenase activity. The findings further support the hypothesis that only the therapeutically active compounds are soybean lipoxygenase inhibitors.

Inhibition of prostaglandin synthetase in human rectal mucosa

Miniaturised methods have been used to construct dose-response curves for the effects of inhibitory drugs on prostaglandin synthesis using individual rectal biopsies obtained from patients with ulcerative colitis. The potency of different drugs has been compared. Sulphasalazine, 5 amino salicylic acid (5-ASA) and N-acetyl 5-ASA inhibited prostaglandin synthesis at high concentration, but sulphapyridine and prednisolone did not. Indomethacin and flurbiprofen were considerably more potent inhibitors. These data imply that sulphasalazine does not act by simple inhibition of prostaglandin synthesis but leave open the possibility that sulphasalazine or 5-ASA may be inhibitors of the synthesis of related lipoxygenase products.

Granulocyte-mediated release of histamine from mast cells. Effect of myeloperoxidase and its inhibition by antiinflammatory sulfone compounds

During phagocytosis, neutrophilic and eosinophilic granulocytes undergo metabolic activation and degranulation. This leads to accumulation of H2O2 and myeloperoxidase (MPO) or eosinophilic peroxidase (EPO) in the extracellular environment in inflammation. In the present investigation we show that the MPO-H2O2-halide system can degranulate isolated mast cells with release of histamine and 3H-serotonin. This is accomplished both in a system containing purified human MPO and in one containing phagocytosing neutrophils. When using purified MPO and a H2O2-generating system, the release was rapid, with 50% release after less than 20 min. The direct histamine release required less (0.65-2 micrograms/ml) MPO than did the release of 3H-serotonin (1-6 micrograms/ml). The release reaction was inhibited by azide, catalase but not superoxide dismutase. Studying the effect of the antiinflammatory sulfone compounds dapsone and sulfapyridine on the MPO-mediated histamine release, we show effective inhibition of the histamine release at concentrations of 0.025-0.2 mM of sulfone. 5-aminosalicylic acid exhibited some inhibition only in the cell-free system, whereas sulfasalazine was inactive. The antiinflammatory effect of dapsone in dermatitis herpetiformis and sulfasalazine in ulcerative colitis may in part be explained by their inhibitory effects on the granulocyte-mediated histamine release from mast cells in skin and mucosal tissue.

Functional suppressor T cell activity in Crohn's disease and the effects of sulphasalazine

Suppressor T cell activity was measured in 18 patients with Crohn's disease and 20 controls, using two different functional assays. The effects of sulphasalazine and its metabolites on in vitro suppressor cell activity were also studied. The activity of a Con A-induced suppressor cell system in patients with Crohn's disease did not differ from that of controls, suggesting that the previously reported abnormalities are a secondary phenomenon. Furthermore, the activity of a non-induced suppressor T cell system was also normal in these patients. There was no evidence either in vivo or in vitro to suggest that sulphasalazine exerts its beneficial action by an effect on this aspect of immunoregulation.

Increased suppressor cell activity in inflammatory bowel disease

We studied the in vitro effect of indomethacin, hydrocortisone, sulphasalazine, and its metabolites sulphapyridine (SP) and 5-amino salicylic acid (5-ASA) on peripheral blood mononuclear cells (PBMC) from 49 patients with inflammatory bowel disease and 34 controls. Indomethacin caused a highly significant increase in the PBMC response to the mitogen PHA-P compared with controls (P less than 0.01), indicating increased activity of a prostaglandin-producing suppressor cell system. On the contrary, sulphasalazine resulted in a reduced response which was significantly greater for the group with inflammatory bowel disease than the control group (P less than 0.05). This reduction was also produced by 5-ASA (P less than 0.05) but not by sulphapyridine. Addition of indomethacin to PBMC incubated with sulphasalazine significantly reduced the effect of sulphasalazine (P less than 0.001). Hydrocortisone resulted in a reduced response which was similar to that of controls and was not altered by the addition of indomethacin. The response to indomethacin, hydrocortisone, sulphasalazine, sulphapyridine, and 5-ASA was not dependent on the HLA type of the patients, disease activity, or drug therapy. The results suggest that increased suppression by a population of prostaglandin-producing suppressor cells plays a role in the immunopathology of inflammatory bowel disease, but that sulphasalazine does not exert its therapeutic effect by acting on this step of the immunoregulatory system. Any trials of indomethacin therapy in inflammatory bowel disease should take into account that, in vitro, sulphasalazine and indomethacin have opposing mechanisms of action in this system.

Inhibition of leucocyte motility by drugs used in ulcerative colitis

The effects on leucocyte motility of sulphasalazine (Salazopyrin) and its metabolites sulphapyridine and 5 amino-salicylic acid have been compared with those of prednisolone and indomethacin. Sulphasalazine, its active metabolite 5 amino-salicylic acid, and prednisolone are all potent inhibitors of leucocyte motility. Sulphapyridine and indomethacin are non-inhibitory. Inhibition of leucocyte motility may explain why sulphasalazine and 5 amino-salicylic acid are effective in ulcerative colitis while sulphapyridine is not. The lack of effect of indomethacin suggests that this action of sulphasalazine does not involve inhibition of prostaglandin synthesis.

Effects of sulphasalazine and its metabolites on prostaglandin synthesis, inactivation and actions on smooth muscle

1 We have investigated the effects of sulphasalazine and of its principal colonic metabolites (5-aminosalicylic acid and sulphapyridine) on prostaglandin inactivation, synthesis and actions on gastrointestinal smooth muscle.2 Sulphasalazine inhibits prostaglandin F(2alpha) breakdown in 100,000 g supernatants in all organs so far tested from 7 species with an ID(50) of approx. 50 muM; it has a selective action on prostaglandin 15-hydroxydehydrogenase and does not inhibit prostaglandin Delta-13 reductase, prostaglandin 9-hydroxydehydrogenase or ;enzyme X' at millimolar concentrations. Enzyme activities were measured radiochemically or by bioassay.3 Sulphapyridine and 5-aminosalicylic acid do not inhibit prostaglandin inactivation in vitro (4 species tested). A methyl analogue of sulphasalazine is a more potent inhibitor than the parent compound. Rabbit colon prostaglandin F(2alpha) metabolism in vitro was inhibited by the following drugs with ID(50) values (muM) of: diphloretin phosphate 20, sulphasalazine 50, indomethacin 220, frusemide 1000 and aspirin 10,000. A similar rank order of potencies was obtained with rabbit kidney.4 Sulphasalazine at 50 to 100 muM inhibited inactivation of prostaglandin E(2) in the perfused rat and guinea-pig lung by 3 to 40% (rat) and 32 to 100% (guinea-pig) when measured by superfusion cascade bioassay and of prostaglandin F(2alpha) by 43.6 +/- 6.5% in rat lung perfused with 50 muM sulphasalazine and assayed radiochemically.5 Prostaglandins E(1) and E(2) were 97.0 +/- 8.2% and 92.3 +/- 6.8% inactivated in the lungs after intravenous injection in the anaesthetized rat as measured by reference to their vasodepressor potencies when injected intra-arterially. Prostaglandin A(2) was not similarly inactivated. Pulmonary inactivation was prevented in the presence of an intravenous infusion of 16.3 mug kg(-1) min(-1) sulphasalazine and partially inhibited at a lower infusion rate.6 Prostaglandin biosynthesis from arachidonic acid was measured in microsomal preparations from four sources by bioassay and radiochemical methods. Indomethacin was a potent inhibitor (ID(50) 0.8 to 4.1 muM) but sulphasalazine and its methyl analogue were very weak inhibitors (ID(50) 1500 to > 5000 muM), 5-aminosalicylic acid was weaker still and sulphapyridine inactive.7 Sulphasalazine at 50 muM did not affect the actions of prostaglandins on five smooth muscle preparations; at 500 muM there was a rapidly reversible and probably non-specific antagonism of responses to low doses of prostaglandins.8 The specificity and selectivity of the interaction of sulphasalazine and its metabolites with the formation, breakdown and actions of prostaglandins are discussed.

Inhibition of neutral proteases from polymorphonuclear (PMN) neutrophils by salicylazosulfapyridine (SASP)

Cytochemical methods were used to demonstrate the inhibitory effect of salicylazosulfapyridine (SASP) on the activity of neutral proteases produced by neutrophilic granulocytes (PMN proteases). The SASP metabolites (5-aminosalicylic acid and sulfapyridine), produced by splitting of SASP by bacteria in the colon, did not inhibit the activity of PMN proteases. Paradoxically, sulfapyridine intensified PMN protease activity. A similar effect however could not be demonstrated for 5-aminosalicylic acid.

Sulfones and sulfonamides in dermatology today

Although dapsone and sulfapyridine have been used for years in dermatology, there has not always been a clear understanding of how these agents work. Recent investigation, however, has shed new light on thes agents which now allows a more rational approach to their use. This review is an attempt to familiarize the clinician with how these agents work, in what disease states they are effective, how to administer them, what adverse effects may occur, and how to monitor the patient to detect these adverse effects.

Role of prostaglandins in ulcerative colitis. Enhanced production during active disease and inhibition by sulfasalazine

Prostaglandin E2 (PGE2) level in rectal mucosa excised from 17 patients suffering from ulcerative colitis was 2-fold higher than that found in rectal mucosa of 17 normal subjects: 2.0 +/- 0.4 and 0.9 +/- 0.2 ng per mg of wet tissue, respectively. Accumulation of PGE 2 in 24-hr cultures of rectal mucosa specimens obtained from patients with ulcerative colitis was 112% higher than that observed in cultures from control subjects. Addition of sulfasalazine, sulfapyridine, and 5-aminosalicylic, acid to the culture medium of ulcerative colitis mucosa resulted in inhibition of PGE2 production by 34, 32, and 62%, respectively, compared to rectal specimens cultured in drug-free medium. These results suggest that PGE may mediate the inflammatory response in ulcerative colitis and that some of the therapeutic effect of sulfasalazine and its constituents are related to the inhibition of PGE synthesis.

The effect of antimicrobial agents on leukocyte chemotaxis

The effects of several chemotherapeutic agents on the chemotaxis of human leukocytes were studied in an in vitro system using a Sykes-Moore chamber and a double-filter technique. Chemotactic factor was generated by the interaction of normal human serum and zymosan. At concentrations comparable to and below therapeutic blood levels, tetracycline HCl, erythromycin base and clindamycin HCl were all inhibitory, causing marked suppression of leukocyte chemotaxis and slight reduction of random migration. Penicillin G-Na, dapsone, and sulfapyridine did not alter white cell motility at the concentrations of drug tested. It is postulated that the capacity of some of these agents to inhibit leukocyte chemotaxis may account, in part, for their efficacy in inflammatory skin diseases such as acne vulgaris.

The presence of new permeability factor in serum of patients with systemic lupus erythematosus and its significance

We have found a new permeability factor in serum of patients with systemic lupus erythematosus. It is non-dialyzable, heat stable, and long acting as compared to histamine or bradykinin which is short acting. It has no esterolytic nor smooth muscle contracting activities. It is not inhibited by anti-histamine drugs, soy bean trypsin inhibitor, DFP or Cl esterase inhibitor. It is independent of the kallikrein system. It has the common antigenicity with IgG Fc fragments. Its approximate molecular weight is about 55,000. So we tentatively call this permeability factor IgG-PF. Intravenous injections of HGG-anti-HGG immune complex, which has been formed by antigen-antibody reactions in 20 times antigen excess, into rats resulted in no immune complex nephritis. However, intravenous injections of HGG-anti-HGG immune complex with IgG-PF resulted in immune complex nephritis in rats. The above immune complex nephritis was inhibited by administrations of sulfapyridine but not by administrations of anti-histamine. These results indicate that IgG-PF plays some roles in the mechanism of immune complex nephritis.

An experiment to determine the active therapeutic moiety of sulphasalazine

Sulphasalazine (S.A.S.P.) is of proven value in the treatment of ulcerative colitis, but its mode of action is unknown. When it is taken by mouth, nearly all the dose reaches the colon intact, where it is split by bacteria into sulphapyridine (S.P.) and 5-aminosalicylic acid (5-A.S.A.). An experiment was devised to determine whether the therapeutic property of S.A.S.P. is a function of the parent molecule or of these two principal metabolites. Retention enemas of S.A.S.P., S.P., and 5-A.S.A. were administered to volunteer patients with sigmoidoscopic evidence of active ulcerative colitis. The experiment was conducted as a blind controlled therapeutic trial, each patient having one of the test enemas daily for two weeks. Pronounced histological improvement was observed in approximately 30% of the patients receiving S.A.S.P. or 5-A.S.A., and in only 5% of those receiving S.P. It is concluded that the active therapeutic moiety of S.A.S.P. IS 5-A.S.A. and that the S.P. functions as a carrier ensuring that the 5-A.S.A. is liberated within the colon.

The effect of immunosuppressive and anti-inflammatory drugs on monocyte function in vitro

MNL cellular chemotaxis, bacterial killing and phagocytosis, and Oil Red O phagocytosis were studied in vitro in the presence of eight anti-inflammatory or immunosuppressive drugs. Inhibition of Boyden Chamber migration of MNL's in a MNL-lymphocyte mixture was achieved after 1/2 hr incubation by 10(-3) and 10(-4) mol/L. concentrations of chloroquine (maximum inhibition 63% +/- 2.8), dexamethasone (58% +/- 8.6), 6-mercaptopurine (62% +/- 4.2), methotrexate (66% +/- 6.4), and vinblastine (100%). Bacterial killing was not significantly affected by any of the drugs studied. Bacterial phagocytosis was improved by vinblastine at 10(-3) and 10(-4)M and by 6-mercaptopurine at 10(-5)M, but there was apparent interference with the assay at high drug concentrations. Modification of the Oil Red O technique showed inhibitions of MNL phagocytosis by vinblastine at 10(-3)M (69% +/- 2.8 inhibition), chloroquine at 10(-3)M (49% +/- 8.5), and mercaptopurine at 10(-3)M (32.5% +/- 0.7). Cyclophosphamide, although reported to require hepatic conversion in vivo, may be partially activated in a lymphocyte-MNL mixture in vitro, producing a decrease in cell viability but no statistically significant impairment of MNL function. These results support direct inhibition of MNL cellular function as one of the mechanisms of the anti-inflammatory action of chloroquine, dexamethasone, methotrexate, 6-mercaptopurine, and vinblastine.

Inhibition of prostaglandin biosynthesis by sulphasalazine and its metabolites

Sulphasalazine (SZ) inhibits prostaglandin (PG) biosynthesis in vitro with a potency comparable to that of aceylsalicylate. The metabolites of SZ, sulphapyridine and 5-aminosalicylic acid, were of considerably lower potency as inhibitors of PG biosynthesis in the synthetase preparations used. Th inhibition of prostaglandin production by SZ could at least partly account for the clinical utility of sulphasalazine in ulcerative colitis. Sulphapyridine may help to maintain inhibitory concentrations of SZ by restraining bacterial breakdown of the active drug.