Serum gold. II. Levels in rheumatoid arthritis

In vitro evaluation of disease-modifying antirheumatic drugs against rheumatoid arthritis associated pathogens of the oral microflora

OBJECTIVES

In the past, the human microbiome has consistently been associated with rheumatoid arthritis (RA) and disease activity. Here, we investigate the antimicrobial activity of disease-modifying antirheumatic drugs (DMARDs) against typical representatives of the oral microflora that have been associated with RA.

METHODS

DMARDs were screened for antimicrobial activity against bacteria that are associated with the pathogenesis of the disease and/or frequently isolated from the oral microflora of patients with RA. Screening was done by an agar diffusion assay and minimum inhibitory concentrations (MICs) of antimicrobial active substances were then determined by broth dilution.

RESULTS

Aurothiomalate and sulfasalazine demonstrated broad-spectrum antimicrobial activity, but with MICs ranging from 18 to >280 µg/mL and 150 to >600 µg/mL, respectively, only at supratherapeutic concentrations. Methotrexate showed antimicrobial activity only against Fusobacterium nucleatum and Viridans streptococci. The corresponding MICs were 3.75 to >30 µg/mL and 0.5-15 µg/mL, respectively, thus at least for streptococci, within the therapeutically achievable range. No other DMARD tested showed antimicrobial activity in the agar diffusion screening assay.

CONCLUSION

Methotrexate, sulfasalazine and aurothiomalate showed antimicrobial activity against a broad spectrum of RA associated pathogens of the oral microflora. While methotrexate showed relevant antimicrobial activity, and to a more limited extent aurothiomalate, sulfasalazine was active only at far supratherapeutic systemic concentrations. Nevertheless, given the highly species-dependent antimicrobial activity and the multiple ways it can affect the human microbiome, our results suggest a link between antimicrobially active antirheumatic drugs and their potential effect in the treatment of RA.

New comprehensive studies of a gold(III) Dithiocarbamate complex with proven anticancer properties: Aqueous dissolution with cyclodextrins, pharmacokinetics and upstream inhibition of the ubiquitin-proteasome pathway

The gold(III)-dithiocarbamate complex AuL12 (dibromo [ethyl-N-(dithiocarboxy-kS,kS')-N-methylglycinate] gold(III)), is endowed with promising in vitro/in vivo antitumor activity and toxicological profile. Here, we report our recent strategies to improve its water solubility and stability under physiological conditions along with our efforts for unravelling its tangled mechanism of action. We used three types of α-cyclodextrins (CDs), namely β-CD, Me-β-CD and HP-β-CD to prepare aqueous solutions of AuL12. The ability of these natural oligosaccharide carriers to enhance water solubility of hydrophobic compounds, allowed drug stability of AuL12 to be investigated. Moreover, pharmacokinetic experiments were first carried out for a gold(III) coordination compound, after i.v. injection of the nanoformulation AuL12/HP-β-CD to female mice. The gold content in the blood samples was detected at scheduled times by AAS (atomic absorption spectrometry) analysis, highlighting a fast biodistribution with a t_β1/2 of few minutes and a slow escretion (t_α1/2 of 14.3 h). The in vitro cytotoxic activity of AuL12 was compared with the AuL12/HP-β-CD mixture against a panel of three human tumor cell lines (i.e., HeLa, KB and MCF7). Concerning the mechanism of action, we previously reported the proteasome-inhibitory activity of some our gold(III)-based compounds. In this work, we moved from the proteasome target to upstream of the important ubiquitin-proteasome pathway, testing the effects of AuL12 on the polyubiquitination reactions involving the Ub-activating (E1) and -conjugating (E2) enzymes.

Aurothioglucose inhibits induced NF-kB and AP-1 activity by acting as an IL-1 functional antagonist

We have designed a series of recombinant CAT genes to study IL-1 signal transduction in murine fibroblast NIH 3T3 cells. We demonstrate that the HSV thymidine kinase (tk) promoter does not respond to IL-1, but that IL-1 induction of this promoter is observed after insertion of either NF-kB or AP-1 binding sites upstream of the HSV tk cap-site. We have studied the effects of indomethacin, dexamethasone and aurothioglucose (which have been used in the treatment of patients affected by rheumatoid arthritis) in the IL-1 inducible CAT assay. We show that aurothioglucose or dexamethasone is able to inhibit IL-1 induced CAT activity whereas a non-steroidal anti-inflammatory drug (indomethacin) is inactive. Order of addition experiments indicate that aurothioglucose, which has disease-modifying activity in treated patients, acts as an IL-1 functional antagonist in this system.

Immunomodulatory effects of therapeutic gold compounds. Gold sodium thiomalate inhibits the activity of T cell protein kinase C

Previous studies have shown that the gold compounds, gold sodium thiomalate (GST) and auranofin (AUR), which are effective in the treatment of rheumatoid arthritis, inhibit functional activities of a variety of cells, but the biochemical basis of their effect is unknown. In the current studies, human T cell proliferation and interleukin 2 production by Jurkat cells were inhibited by GST or AUR at pharmacologically relevant concentrations. Because it has been documented that protein kinase C (PKC) is involved in T cell activation, the capacity of gold compounds to inhibit PKC partially purified from Jurkat cells was assayed in vitro. GST was found to inhibit PKC in a dose-dependent manner, but AUR caused no significant inhibition of PKC at pharmacologically relevant concentrations. The inhibitory effect of GST on PKC was abolished by 2-mercaptoethanol. To investigate the effect of GST on the regulation of PKC in vivo, the levels of PKC activity in Jurkat cells were examined. Cytosolic PKC activity decreased slowly in a concentration- and time-dependent manner as a result of incubation of Jurkat cells with GST. To ascertain whether GST inhibited PKC translocation and down-regulation, PKC activities associated with the membrane and cystosolic fractions were evaluated after phorbol myristate acetate (PMA) stimulation of GST incubated Jurkat cells. Translocation of PKC was markedly inhibited by pretreatment of Jurkat cells with GST for 3 d, but the capacity of PMA to down-regulate PKC activity in Jurkat cells was not altered by GST preincubation. The functional impact of GST-mediated downregulation of PKC in Jurkat cells was examined by analyzing PMA-stimulated phosphorylation of CD3. Although GST preincubated Jurkat cells exhibited an increased density of CD3, PMA-stimulated phosphorylation of the gamma chain of CD3 was markedly inhibited. Specificity for the inhibitory effect of GST on PKC was suggested by the finding that GST did not alter the mitogen-induced increases in inositol trisphosphate levels in Jurkat cells. Finally, the mechanism of the GST-induced inhibition of PKC was examined in detail, using purified PKC subspecies from rat brain. GST inhibited type II PKC more effectively than type III PKC, and also inhibited the enzymatic activity of the isolated catalytic fragment of PKC. The inhibitory effect of GST on PKC activity could not be explained by competition with phospholipid or nonspecific interference with the substrate. These data suggest that the immunomodulatory effects of GST may result from its capacity to inhibit PKC activity.

Thiol-containing compounds inhibit the production of monocyte/macrophage-derived angiogenic activity

Macrophage (M phi)-mediated angiogenesis is believed to play an important role in the pathogenesis of rheumatoid arthritis. Gold sodium thiomalate, which is used in the treatment of rheumatoid arthritis, is a potent inhibitor of the production of m phi-derived angiogenic activity. To determine the mechanism of this inhibition, we studied the effects of thiol containing compounds (TCCs) on elicited mouse peritoneal m phi and lipopolysaccharide stimulated normal human monocytes. Monocyte/m phi conditioned media were potently angiogenic when assayed in rat corneas, while conditioned media from viable monocyte/m phi s treated with TCCs (at concentrations of 8.3-16.6 x 10(-5) M) were not. TCCs inhibited production of angiogenic activity by the m phi s rather than affecting other components of the angiogenic response such as the angiogenic factors or the target microvasculature of the rat cornea. Levels of the angiogenic mediator tumor necrosis factor-alpha (TNF-alpha) were not decreased in conditioned media of monocyte/m phi s treated with TCCs. We conclude that TCCs are potent inhibitors of the production of m phi-mediated angiogenic activity. This action of TCCs on m phi s may be in part responsible for the mechanism of action of therapeutic gold compounds in rheumatoid arthritis.

The modulation of interleukin 1 production by interferon gamma, and the inhibitory effects of gold compounds

We have studied the in vitro effects of gold sodium thiomalate (GST) and auranofin (Auf) on the production of interleukin 1 (IL1) expressed as thymocyte co-stimulatory activity (TCSA), and interleukin 1 beta (IL1 beta) as modulated by interferon gamma (IFN gamma). Adherent cells (ADC), of which 80% were monocytes, were obtained from human peripheral blood, and stimulated with lipoprotein polysaccharide (LPS) for 24-48 h. TCSA and IL1 beta production by fresh ADC (0-24 h) was significantly higher than that of aged ADC (24-48 h). The addition of IFN gamma to ADC cultures, however, maintained the capacity of aging ADC to respond optimally to LPS. The addition of GST or Auf inhibited this modulatory effect of IFN gamma, resulting in a marked reduction of TCSA and IL1 beta production. The effects of IFN gamma on the production of IL1 may be important in the pathogenesis of rheumatoid arthritis (RA). The inhibition by GST and Auf of IFN gamma modulation may contribute to the therapeutic efficacy of these drugs in RA.

In vitro effects of two gold compounds, and D-penicillamine on the production of interferon gamma

There are contradictory reports on Interferon Gamma (IFN gamma) production by peripheral blood mononuclear cells (PBMC) in rheumatoid arthritis (RA). Since many patients previously studied were on Gold Sodium Thiomalate (GST), Auranofin (Auf), or D-Penicillamine (D-Pen) we have investigated the effects of these drugs on IFN gamma production using PBMC from normal controls (NC), and RA patients off GST, Auf, and D-Pen. Auf in low concentrations enhanced IFN gamma production by PBMC from NC but not RA; GST, and D-Pen had no effect. In other experiments PBMC were stimulated with concanavalin A (CONA A), or phytohemagglutinin (PHA). Auf, and GST inhibited IFN gamma production by CON A - stimulated NC and RA cells; D-Pen had no effect. Auf in low concentrations enhanced IFN gamma production by PHA - stimulated NC cells, but this effect was not seen with RA cells; GST inhibited both RA and NC cell production of IFN gamma, and D-Pen had no effect. Auf has a biphasic effect on IFN gamma production by NC cells with low concentrations being stimulatory or co-stimulatory, possibly by acting on T helper cells. Higher concentrations of Auf and GST, equivalent to those achieved in vivo in the course of therapy, inhibit IFN gamma production. These results suggest that gold therapy may affect IFN gamma production in RA, and could explain discrepancies noted in previous studies.

Low-dose gold compounds inhibit fibroblast proliferation and do not affect interleukin-1 secretion by macrophages

We examined the effect of low concentrations of gold compounds on the proliferation of human fibroblasts. Gold sodium thiomalate (GST) inhibited both basal and interleukin-1-induced tritiated thymidine incorporation into fibroblasts in a dose- and time-dependent manner. Significant inhibition was observed at the level of 5 micrograms/ml GST, and greater than 50% inhibition was attained at 10 micrograms/ml. These concentrations are attainable in the serum of treated patients. Similar inhibition was observed when less than 1 micrograms/ml auranofin, which is also within a serum-attainable range, was added. Low concentrations of GST (0-10 micrograms/ml) did not affect interleukin-1 secretion from lipopolysaccharide-stimulated human mononuclear phagocytes (M phi) when assessed by both human fibroblast and C3H/HeJ mouse thymocyte proliferation assays. When M phi precultured for 48 hours with GST (0-10 micrograms/ml) were added to the fibroblast culture in the presence or absence of lipopolysaccharide, there was no significant inhibition of M phi-induced DNA synthesis of fibroblasts. In contrast, when fibroblasts were precultured with GST (0-10 micrograms/ml) for 48 hours and freshly separated M phi were added, significant inhibition was observed in M phi-induced fibroblast proliferation at 5 micrograms/ml. These results suggest that low concentrations of GST directly cause a reduction of fibroblast proliferation, but do not affect the capability of M phi for induction of fibroblast proliferation. Therefore, gold compounds may play a role in the inhibition of the growth of rheumatoid pannus by direct inhibition of fibroblast proliferation.

Inhibition of in vitro proliferative response of cultured T lymphocytes to interleukin-2 by gold sodium thiomalate

Gold sodium thiomalate (GST), in concentrations attainable during chrysotherapy for rheumatoid arthritis, significantly inhibited the proliferative responses of cultured T cells stimulated by interleukin-2 (IL-2). The observed suppression was not related to altered kinetics, cell death, or interference with the binding of IL-2 to cell surface receptors. It appeared that GST affected an early step in the proliferative process, since maximum inhibition was obtained by the addition of GST within 4 hours of stimulation; progressive reduction of suppression was observed when GST was added later. Significant inhibition occurred when cultured T cells were preincubated for 24 hours with GST and washed prior to IL-2 stimulation, although the degree of suppression was decreased. Thus, inhibitory activity was not dependent on the continued presence of GST throughout culture. These findings suggest that there is a direct inhibition of T lymphocytes by GST, which may be important in immunomodulation by gold compounds.

Sodium aurothiomalate inhibits T cell responses to interleukin-2

We studied the effects of the gold compound sodium aurothiomalate (SATM) on the responses of murine CTLL2 cells, and human T cells to Interleukin-2 (IL-2). SATM inhibited tritiated thymidine (3HTdR) incorporation by CTLL2 cells stimulated with human recombinant IL-2. Human T cells were cultured with phytohemagglutinin (PHA) in separate experiments and IL-2 receptor expression measured by using immunofluorescent anti-Tac serum; SATM inhibited IL-2 receptor expression. Furthermore, SATM when added concurrently with PHA, and IL-2 inhibited 3HTdR incorporation by human T cells in 5 day cultures. The kinetics of inhibition were further studied by adding PHA to T cells for 48 hours followed by the addition of SATM and IL-2; SATM inhibited 3HTdR incorporation even though receptor expression had occurred. These results suggest that SATM inhibits the stimulatory effects of IL-2 on T cells partly by interfering with IL-2 receptor expression, and partly by other mechanisms of action. These effects of SATM may explain some of the conflicting data in the literature on T cell responses to IL-2 in rheumatoid arthritis (RA), and suggest a possible mechanism of action for the drug in the treatment of RA.

Aurothioglucose overdosage in five patients with rheumatoid arthritis

Five patients with active seronegative, rheumatoid arthritis, HLA-DR3 negative, received inadvertently 250 to 500 mg of aurothioglucose instead of their usual weekly dose, during standard remission-inducing chrysotherapy. Subsequently a rapid and sustained clinical remission appeared in all five patients.

Gold-induced aplastic anemia

Three patients receiving gold salt treatment for rheumatoid arthritis developed severe aplastic anemia. All three patients experienced remission of their disease at the time of the occurrence of marrow aplasia. Reviewing data on these patients and recent literature indicate that fatal marrow aplasia seems to occur more frequently in sero-negative women who respond well to therapy with gold salts. Frequent blood monitoring in search for any pronounced or sustained drop in red, white or platelet count, even within normal range could serve as a warning sign for myelotoxicity. Despite intensive supportive measures and specific therapeutic attempts, all three patients eventually died of septic shock.

Inhibition of human endothelial cell proliferation by gold compounds

Neovascularization has a role in the propagation of rheumatoid synovitis because the spread of mononuclear cell infiltration and the growth of pannus are dependent on the growth of new blood vessels. Growth of such vessels requires local endothelial cell (EC) proliferation. Inhibition of synovial EC proliferation, therefore, would have the potential to diminish rheumatoid inflammation. We have, therefore, studied the effects of gold sodium thiomalate (GST), auranofin, and gold chloride on the proliferation of human umbilical vein EC. GST suppressed both basal and EC growth factor-induced tritiated thymidine incorporation into EC in a dose-dependent fashion. Inhibition was observed with concentrations as low as 1 microgram/ml GST, 5 micrograms/ml gold chloride, and 0.1 microgram/ml auranofin, levels attainable in blood and synovium of patients. These results suggest that gold compounds have an antiangiogenic effect. The low concentrations inhibiting EC proliferation suggest that gold compounds may suppress rheumatoid synovitis by reducing the number of small blood vessels available for mononuclear cell infiltration and synovial tissue proliferation.

Serum gold concentrations during treatment with auranofin

Serum gold concentrations were measured in rheumatoid arthritis patients during chronic treatment with the orally adsorbable gold compound auranofin. In agreement with data in the literature, the highest serum gold concentration was reached after 16 weeks of treatment with 6 mg auranofin daily. A striking finding in this study was that thereafter the serum gold concentrations did not appear to plateau but declined gradually. Statistically this resulted in a significantly lower concentration after one year as compared with week 16 (p less than 0.05, paired t-test). It is suggested that a shift from protein bound gold to cell-bound gold might be the explanation.

Binding of sodium aurothiomalate to human serum albumin in vitro at physiological conditions

The binding of aurothiomalate to human serum albumin was studied by equilibrium dialysis at 37 degrees C, pH 7.3-7.4, and ionic strength 0.15-0.16 mol/l. It was found that aurothiomalate was bound to albumin at one site with an apparent association constant K1 = 3.0 X 10(4) M-1 and at three or more sites with the sum of association constants of the order of 10(3) M-1. Valuable information of the aurothiomalate-albumin interaction was deduced from the observed changes of pH of the albumin solutions during dialysis. A conceivable binding mechanism consistent with the results might be that aurothiomalate binds as Au+ to the high affinity binding site by exchanging a H+ and that this site might be the sulphydryl group in cysteine34; and that aurothiomalate binds as monomeric anions to the lower affinity binding sites.

Clinical pharmacokinetics of oral and injectable gold compounds

The pharmacokinetics of oral gold (auranofin) in some respects resemble, and in other respects differ from, those of existing parenteral gold compounds such as gold sodium thiomalate (GST). This may in part relate to physicochemical differences as GST is a water-soluble polymeric compound in vitro whereas auranofin is lipid-soluble and characteristically monomeric. Furthermore, intramuscularly administered gold is greater than 95% bioavailable, whereas only 20 to 30% of an orally administered dose of auranofin is absorbed. Following a standard 50mg intramuscular injection of GST, serum gold concentrations rise sharply, peaking between 4 and 8 mg/L in approximately 2 hours and declining to an average of 3 mg/L by 7 days. With repeated injections of GST stable serum concentrations of gold (3 to 5 mg/L) are eventually achieved (usually within 5 to 8 weeks) although absolute concentrations may vary widely between patients. On the other hand, long term treatment with auranofin is associated with lower and more stable serum concentrations of gold (0.5 to 0.7 mg/L), on the standard dosing regimen of 6 mg daily. Both compounds are retained within the body for prolonged periods. However, the amount of gold retained with auranofin is significantly less compared with GST (less than 5% of a tracer dose of auranofin--about 20% of the absorbed dose--is retained by 100 days whereas the retention for a single labelled dose of GST over a similar interval is greater than 50%). Excretory patterns of GST and auranofin also differ. Most of an absorbed dose of GST (greater than 70%) is excreted by the kidneys whereas only 50% of an absorbed (15% of an administered) dose of auranofin is excreted in the urine. Both compounds are avidly bound by plasma proteins and auranofin shows a particularly strong association with circulating cellular elements. In human subjects, parenterally administered gold is widely distributed among bodily tissues, showing a predilection for tissues of the reticuloendothelial system as well as the kidney and adrenal cortex. Comparable studies in humans are not available for auranofin but animal studies have shown comparatively less affinity for the liver, kidney and spleen. Valuable insight has been gained in analysing the comparative pharmacokinetics of oral and injectable gold compounds. Unfortunately, attempts to correlate pharmacokinetic findings with clinical response or pharmacodynamic changes, as a whole, remain largely unsuccessful with these agents.

Lack of correlation between blood gold concentrations and clinical response in patients with definite or classic rheumatoid arthritis receiving auranofin or gold sodium thiomalate

We investigated the correlation between whole blood gold concentrations and clinical outcomes in 59 auranofin-treated patients and 51 gold sodium thiomalate-treated patients who completed a 21-week, placebo-controlled, multicenter parallel trial. Whole blood gold concentrations did not correlate with clinical outcome, as assessed by changes in joint tenderness, joint swelling, or Westergren erythrocyte sedimentation rate. They also did not correlate with toxic reactions necessitating withdrawal from the study.

Free thiomalate levels in patients with rheumatoid arthritis treated with disodium aurothiomalate: relationship to clinical outcome of therapy

Sixteen patients with seropositive rheumatoid arthritis were treated with 20 mg disodium aurothiomalate (Myocrisin) weekly for six months. Disease activity was assessed before and after treatment. Plasma profiles and urinary excretion of free thiomalate were measured in all patients after the initial injection and again at six months in the 12 patients remaining on therapy. No difference was found in plasma levels or urinary excretion of free thiomalate between patients who responded to treatment or who developed toxic reactions and those who did not.

Auranofin. A preliminary review of its pharmacological properties and therapeutic use in rheumatoid arthritis

Auranofin is the first orally active gold compound for the treatment of rheumatoid arthritis. Like other chrysotherapeutic agents, its exact mechanism of action is unknown, but it probably acts via immunological mechanisms and alteration of lysosomal enzyme activity. Although long term clinical experience with auranofin is limited, its efficacy appears to approach that of sodium aurothiomalate. Further comparative studies with aurothioglucose, hydroxychloroquine and D-penicillamine are required before definitive statements can be made regarding the relative efficacy of auranofin and these agents. While patients have demonstrated clinical remission of rheumatoid arthritis in response to auranofin therapy, radiological studies have been inconclusive regarding its effect on the occurrence or progression of erosive lesions. Auranofin is relatively well tolerated in most patients, but diarrhoea, skin rash, and pruritus are sometimes troublesome, and thrombocytopenia and proteinuria are potentially serious side effects which may occur during therapy. Whereas mucocutaneous side effects are more frequent with injectable gold compounds, gastrointestinal reactions are the most common adverse effect seen with auranofin. The frequency of side effects has been similar with auranofin and sodium aurothiomalate, but they are generally less severe with auranofin. While some of the side effects are controlled by a reduction in dosage, temporary or permanent withdrawal of auranofin may be necessary. Auranofin is clearly a useful addition to the limited list of agents with disease-modifying potential presently available for the treatment of rheumatoid arthritis. It will doubtless generate much interest as its final place in therapy becomes better defined through additional well-designed studies and wider clinical experience.

Comparative pharmacokinetics of triethylphosphine gold (auranofin) and gold sodium thiomalate (GST)

The pharmacokinetics of gold sodium thiomalate (GST) and triethylphosphine gold (auranofin; AF) are different. Gold sodium thiomalate (GST) is completely bioavailable while only 15-25% of auranofin (AF) is absorbed. Protein binding of AF occurs to a larger extent to macroglobulins than does GST and total body retention of GST is much greater than AF at six months (30% versus approximately 1%). While terminal serum half-lives are approximately equal, total body half-lives are 250 days for GST and 69 days for AF. In addition, excretory pathways contrast markedly, with 85% of AF appearing in the feces while only 30% of GST is excreted by this route; 15% of AF gold appears in the urine and approximately 70% of GST gold is excreted via this route. With all the above differences one would expect that organ and cellular distribution of these compounds would differ. While gold from both drugs is concentrated in kidney, the percent of the dose found in the kidneys is less for AF than GST, at least in animals (0.4% vs 4.8%). Minute quantities are found in other organs but more study is needed to more clearly define organ distribution of these gold compounds, particularly in man.

Auranofin: a unique oral chrysotherapeutic agent

Auranofin is a chemically unique gold coordination complex with demonstrated antiarthritic properties on oral administration. Its pharmacokinetic and immunologic profiles are distinct from injectable gold compounds. When auranofin is added to a regimen of salicylates and/or a nonsteroidal antiinflammatory drug for the treatment of RA, significant additional therapeutic benefit is observed. Published studies indicate that auranofin given 6 mg per day approaches the efficacy of parenteral gold salts in the treatment of rheumatoid disease. Noticeable improvement in clinical and laboratory parameters of disease activity has been observed by the third month of auranofin therapy. Further benefit occurs in some patients during the remainder of the first year of treatment. In the more than 3,000 patients treated with auranofin, the most frequently reported side effects were gastrointestinal (mainly diarrhea) and mucocutaneous. Most side effects were mild in nature and the withdrawal rate due to all adverse reactions averaged 11%. Auranofin differs from injectable gold by producing more gastrointestinal but fewer mucocutaneous reactions. The severity of these reactions is less with auranofin and causes fewer withdrawals from therapy.

Inhibition of polyclonally induced immunoglobulin secretion by aurothiomalate

The influence of sodium aurothiomalate on the secretion of immunoglobulins by normal human lymphocytes in vitro was investigated by means of a reverse hemolytic plaque forming cell (PFC) assay. Aurothiomalate inhibited the PFC response induced by pokeweed mitogen (PWM) and by Epstein-Barr virus (EBV) in a dose dependent manner. The inhibition was irreversible, as pre-incubation for 2 h with the drug followed by extensive washing and further culture in gold salt-free medium still caused an inhibition of the PFC response to PWM and to EBV. Cell proliferation was not significantly affected, suggesting that the inhibition of PFC formation was not due to cytotoxicity. Pre-incubation of monocytes/macrophages (Mø's), T lymphocytes and B lymphocytes with the gold compound prior to culture with PWM showed that Mø's and B cells were highly sensitive, whereas T lymphocytes were resistant to the drug. The findings indicate that aurothiomalate inhibits the polyclonally induced PFC response by interfering with accessory Mø function and by affecting the B lymphocyte itself.

Auranofin versus injectable gold. Comparison of pharmacokinetic properties

The new oral gold compound auranofin differs pharmacokinetically from the existing injectable gold compounds such as gold sodium thiomalate. Following a standard 50 mg intramuscular injection of gold sodium thiomalate, plasma gold levels rise sharply, peak between 400 and 800 micrograms/dl in approximately two hours, then decline to approximately 300 micrograms/dl by seven days. With repeated 50 mg weekly injections, stable plasma concentrations are gradually achieved, although absolute levels vary greatly among individual subjects. On the other hand, auranofin is associated with lower (50 to 70 micrograms/dl) and more predictable plasma concentrations. Single-dose kinetic studies using isotopically labelled gold show that the plasma disappearance half-time for gold sodium thiomalate is relatively rapid (approximately six days) compared with 17 days for auranofin. Both compounds are retained within the body over prolonged periods. Retention of auranofin is much less, about 1 percent of the original tracer dose remaining at 180 days, compared with more than 30 percent retention of gold sodium thiomalate. Excretory pathways are notable different. The majority of gold sodium thiomalate (greater than 70 percent) is excreted by the kidneys, with the remaining fraction appearing erratically in the stool. In contrast, the enteric pathway represents the major excretory route for auranofin, with nearly 85 percent of the dose eventually recoverable in the stool and less than 15 percent in the urine. In human subjects, parenterally administered gold is almost universally dispersed among body tissues, although highest concentrations occur in the organs of the reticuloendothelial system and the adrenal and renal cortices. Comparable studies are not available for auranofin, but animal studies show comparatively less affinity for liver, kidney, and spleen. To date, attempts to correlate the pharmacokinetics of the injectable gold compounds with clinical response and toxicity have been largely unsuccessful. The distinctive pharmacokinetic profile of auranofin, when compared with gold sodium thiomalate, may nonetheless account in part for the clinical and pharmacologic differences between these compounds.

Parenteral gold in the treatment of rheumatoid arthritis

For over 50 years, gold therapy has played an important role in the treatment of rheumatoid arthritis. Since 1932, many clinicians and investigators have confirmed the beneficial effects of the water-soluble gold salts, aurothioglucose and gold sodium thiomalate. Gold therapy is indicated for patients with active disease who are not responsive to conservative therapy. To minimize patient risks, contraindications must be considered, and careful clinical and laboratory monitoring must be performed under close supervision by the physician during therapy. Side effects may include vasomotor reactions, dermatitis, stomatitis, leukopenia, proteinuria, nephrosis, and thrombocytopenia. During therapy, one of six patients may have an adverse reaction requiring suspension or termination of therapy. Of the five tolerating gold, one will not benefit, three may have marked improvement, and one may have a remission. The usual recommended dosage schedule is intramuscular injection of 25 to 50 mg of gold salt at weekly intervals until a total of 1,000 mg has been achieved. At this level, gold injections may be spaced biweekly, triweekly, and then monthly for an indefinite period.

Comparison of auranofin, gold sodium thiomalate, and placebo in the treatment of rheumatoid arthritis. A controlled clinical trial

A prospective controlled, double-blind multicenter trial compared placebo, auranofin (an orally administered gold complex), and parenteral gold sodium thiomalate (GST) in patients with active rheumatoid arthritis (RA). Of 193 patients who received any treatment, the only important improvement identified for either auranofin or GST was for pain/tenderness scores. When 161 patients who completed 20 weeks of treatment were examined, both auranofin and GST treatments were superior to placebo as measured by improvement in number of painful and/or tender joints, joint pain/tenderness scores, physician's assessment of disease activity, and decrease in erythrocyte sedimentation rate when elevated at entry. GST was superior to placebo in improvement of joint swelling scores, anemia, thrombocytosis, and rheumatoid factor. No drug-related remissions were observed. The only statistically significant advantages of GST over auranofin for efficacy were an increase in hemoglobin concentration and decrease of thrombocytosis with GST. Withdrawals for adverse effects were 5 times more frequent with GST treatment. Thrombocytopenia, proteinuria, elevated liver enzymes, "nitritoid" reactions, and "gold pneumonitis" were observed only in the GST treatment group. These results confirm that both parenteral and oral gold may be effective for the treatment of RA, that GST tends to show greater efficacy than auranofin, and that auranofin has fewer significant adverse effects than GST. However, long-term benefits, tolerability, and safety cannot be inferred from this study.

Effect of heavy metals on human rheumatoid synovial cell proliferation and collagen synthesis

The dose-dependent effects of heavy metals on cell proliferation, collagen synthesis, and non-collagen protein synthesis were studied in early passage cultures of human synovial cells exposed to 1-100 microM concentration of gold, silver, mercury, cadmium or lead for 5 days. The incorporation of [3H]thymidine into trichloroacetic acid insoluble material was inhibited 50% by each of the heavy metals at concentrations between 1 and 10 microM. Gold, lead and mercury (10 microM) decreased the DNA content of the cultures by less than 15%; silver (10 microM) and cadmium (10 microM) resulted in decreased DNA content, which was attributed to cytotoxicity. A dose-dependent inhibition of [3H]proline incorporation into bacterial collagenase resistant (non-collagen) protein was observed after incubation with 10 microM mercury, lead and silver. During incubations with 10 microM gold and cadmium, collagenase resistant protein accumulation increased. All the heavy metals except for gold inhibited collagen accumulation to a greater extent than non-collagen protein accumulation. Gold (10 microM) stimulated the amount of collagen produced per cell, and the percentage of collagen to total protein was increased 50%. The rate of collagen accumulation in medium decreased during incubation with 10 microM silver, mercury, cadmium and lead. The stimulation of collagen synthesis may be a unique property of gold related to the therapeutic indices of gold, compared to other heavy metals, in rheumatoid arthritis.

Mechanism of action, pharmacology, clinical efficacy and side effects of auranofin. An orally administered organic gold compound for the treatment of rheumatoid arthritis

The mechanism of action of auranofin, an oral organic gold compound used in the treatment of rheumatoid arthritis, is probably similar to the previously available parenteral gold compounds. Auranofin affects polymorphonuclear cells and monocytes at lower concentrations than gold sodium thiomalate and generally affects humoral and cell-mediated immunity in the same direction as the latter drug. The pharmacokinetics of auranofin are different from the intramuscular gold compounds. Auranofin is 20-25% orally absorbed and has less total body retention, greater fecal excretion, and less urinary excretion than gold sodium thiomalate. This may be due in part to its differing chemistry, including its lipophilicity and monomeric structure (at least in vitro). While many clinical studies are not yet complete, auranofin (6 mg/day) is clearly more effective than placebo for treating rheumatoid arthritis. Its efficacy relative to gold sodium thiomalate is not clear. Auranofin may be slightly less effective than gold sodium thiomalate, but because it is generally less toxic than intramuscular gold compounds, its therapeutic index may be more favorable.

A comparison of the effects of two gold-containing therapeutic agents on articular chondrocyte growth in vitro

Chondrocyte structure and function under the influence of two gold-containing therapeutic agents, aurothioglucose and triethylphosphine gold, were studied in a monolayer culture system for cultivating lapine articular chondrocytes. The functional parameters investigated were chondrocyte proliferation and the incorporation of 35SO4 as indicator of glycosaminoglycan synthesis. Aurothioglucose (0.2, 1 and 10 micrograms/ml) failed to affect either parameter and caused no cytotoxic effect detectable with the light microscope. Triethylphosphine gold (1.5 and 3 micrograms/ml) prevented subcultured chondrocytes from forming monolayers and was cytotoxic to chondrocytes present in established monolayers, studied with the light and scanning electron microscope. A 0.3 microgram/ml concentration did not alter chondrocyte proliferation or sulphate incorporation and was not cytotoxic.

Gold in erythrocytes, whole blood, and plasma during long-term chrysotherapy

The concentrations of gold in erythrocytes, whole blood, cell-rich plasma, and cell-free plasma were investigated in 17 patients with rheumatoid arthritis undergoing long-term chrysotherapy. Gold estimations were performed with a graphite tube atomic absorption spectrophotometer. Significant quantities of gold were found in isolated erythrocytes of 12 patients. There was no correlation between erythrocyte gold and therapeutic response, plasma gold, and gold in whole blood. Nor did gold in whole blood or plasma show any correlation with therapeutic responses and toxic reaction. However, all patients (3) with toxic reactions had a significantly higher gold concentration in the erythrocytes than the patients without toxic reactions. This result indicates that erythrocyte gold estimations could provide a useful warning of impeding toxic reactions.

Remission-inducing drugs in rheumatoid arthritis

The administration of certain drugs to patients with established rheumatoid arthritis frequently results in improvement that is slow to appear but persists for long periods, even after the drug is discontinued. The three main drugs with this effect, whose efficacy and toxicity are reviewed in this paper, are gold salts, D-penicillamine and chloroquine. The cytotoxic agents used to treat rheumatoid arthritis, which likely have nonspecific anti-inflammatory actions and have serious long-term side effects, are also briefly reviewed. A new drug, levamisole, is currently being tested in patients with rheumatoid arthritis. It is suggested that the time for considering the introduction of a remission-inducing drug in patients with progressive rheumatoid arthritis is after an adequate trial of therapy with salicylates or other nonsteroidal anti-inflammatory agents, or both, and before the oral administration of steroids. It is difficult, however, on the basis of rigorous clinical comparisons, to recommend which of the three main remission-inducing drugs should be tried first, although gold salts have been used the most. Patients who have improved with 6 months of chrysotherapy may continue treatment for at least 3 years, during which time the frequency of mucocutaneous and renal toxic effects will steadily decrease. Some aspects of the medical economics of therapy with remission-inducing drugs for rheumatoid arthritis are discussed.

Gold binding to blood cells and serum proteins during chrysotherapy

The binding of gold to peripheral erythrocytes and serum protein fractions was studied during chrysotherapy of 1 to 2 years' duration in 43 patients with rheumatoid arthritis. In 45% of the patients more than 10% of the gold was found to be strongly bound to blood cells. 5--15% of the metal is bound to non-albumin protein fractions at serum gold concentrations larger than 2 microgram/ml. In contrast to the cellular binding of gold the relative binding of gold to non-albumin proteins was inversely proportional to the serum concentrations. Binding to neither blood cells nor to non-albumin protein fractions was found to be correlated with clinical parameters.

Effects of antirheumatic drugs on protein sulphydryl reactivity of human serum

The effect of a number of antirheumatic drugs on sulphydryl group reactivity in human serum has been determined using the thiol reagent, 5,5′-dithiobis (2-nitrobenzoic acid) (DTNB). Drug effects in vivo have been measured using sera from patients with rheumatoid arthritis receiving these compounds and the drugs have also been added to healthy human serum in vitro. An increased rate of sulphydryl-disulphide exchange between serum sulphydryl groups and DTNB was noted in rheumatoid disease. This finding was not associated with anti-inflammatory drug therapy. In vivo, non-steroidal anti-inflammatory drugs did not affect this reaction, but aurothiomalate, D-penicillamine and levamisole all significantly increased the rate of sulphydryl-disulphide exchange. When the drugs were added to healthy human serum in vitro, indomethacin, aurothiomalate and D-penicillamine stimulated sulphydryl reactivity with DTNB but levamisole had no effect. Aurothiomalate appeared to act in this system as a mixture of gold atoms and thiomalate molecules, the thiomalate stimulating and the gold inhibiting thiol reactivity. This study demonstrates that the stimulation of sulphydryl-disulphide exchange reactions in vivo is a property of three long-acting drugs used to treat rheumatoid arthritis, but not of non-steroidal antiinflammatory agents. This reactivity may therefore differentiate the second-line drugs showing true antirheumatic activity from ‘simple’ anti-inflammatory compounds. Comparative studies have shown that the addition of drugs to serum in vitro may give different results from those obtained with sera from rheumatoid patients receiving these agents. This may be due to in vivo metabolism of the compound, drug concentration effects or the parameters of the in vitro assay system. In view of this, caution is required in the interpretation of data obtained from in vitro studies of these compounds.

A tissue culture model of cartilage breakdown in rheumatoid arthritis. III. Effects of antirheumatic drugs

The effects of hydrocortisone, indomethacin, and gold thiomalate on proteoglycan release were assessed in bovine nasal cartilage-rheumatoid synovium cocultures. Of the three agents, only hydrocortisone consistently inhibited both basal and synovium-stimulated cartilage breakdown. Hydrocortisone responsivity was a direct function of the degradative capacity of synovial specimens, and this was equally well demonstrated both in patients receiving long-term therapy and those given perioperative glucocorticoid therapy. The data are consistent with significant hydrocortisone inhibition of lysosomal enzyme-mediated degradation of cartilage.

Inhibition of neutrophil migration by sera from patients with rheumatoid arthritis

Sera from patients with rheumatoid arthritis inhibited the migration of human neutrophils in 63% (twenty-two out of thirty-five) of the cases tested. The inhibition was not due to a toxic effect of the serum as it was reversed by a chemotactic stimulus. There was a strong correlation between the degree of inhibition of neutrophil migration and the amount of immune complexes present in the sera as determined by the C1q binding activity. It is suggested that the inhibition of neutrophil migration is due to the presence of circulating immune complexes, and that the capacity of immune complexes to inhibit neutrophil migration in vitro may also contribute to the accumulation of neutrophils at sites of immune complex formation in vivo.

Effect of gold sodium thiomalate on murine lymphocyte functions

The in vitro effects of gold sodium thiomalate (GTM) on various murine splenic lymphocytic functions were tested. The presence of GTM in cultures of splenic cells suppressed anti-hapten responses to both thymus-independent and thymus-dependent antigens. GTM also suppressed the in vitro generation of cytotoxic effector cells as well as the mitogenic response to both T cell and B cell mitogens. This suppression could not be reversed by the addition of irradiated spleen cells. Spleen cells exposed to GTM for 4 hr prior to culture also exhibited similarly suppressed functions, although their functional capacity could be fully restored by the addition of irradiated spleen cells. These results show that GTM inhibits both humoral and cellular immune mechanisms and appears to act primarily at the accessory (macrophage) cell level, with perhaps a secondary effect on T lymphocytes.

Neutropenia associated with chrysotherapy for juvenile rheumatoid arthritis

Severe neutropenia, in the absence of generalized bone marrow depression, is a rare complication in adults receiving chrysotherapy for rheumatoid arthritis and has not been described in children. Isolated, severe neutropenia developed in five children with systemic onset JRA while they were receiving gold injections. This potentially fatal complication occurred within eight weeks of beginning therapy in four patients, and after 24 weeks of well-tolerated therapy in the fifth. Leukopenia preceded neutropenia in two children. Localized infection was successfully treated in one child; septicemia was fatal to a second child. Neutropenia resolved within eight to 14 days of its onset in the four survivors; chelation with dimercaprol in one child did not appear to alter the recovery time. It is suggested that a systemic onset of JRA in children less than 6 years of age identifies a higher risk group developing severe neutropenia during chrysotherapy. Cessation of gold therapy upon recognition of a decreasing neutrophil count may prevent or ameliorate a developing neutropenia; careful observation for, and early treatment of, infection may alter its outcome.

Prostaglandin production by macrophages and the effect of anti-inflammatory drugs

1 Macrophages derived from peritoneal cavity inflammatory exudates of guinea-pigs produced substantial amounts of prostaglandin E2-like activity during in vitro culture, so providing the basis for an experimental model of prostaglandin production during inflammatory reactions. 2 Dose-related inhibition of prostaglandin biosynthesis was demonstrated by 16 acidic non-steroidal anti-inflammatory drugs. 3 Seven anti-inflammatory glucocorticosteroid preparations inhibited prostaglandin production in a dose-related manner. The relative potencies of dexamethasone, prednisolone and hydrocortisone were consistent with clinical anti-inflammatory ranking. Cortisone, however, failed to inhibit macrophage prostaglandin production. 4 Three other agents used in the treatment of inflammatory joint diseases were examined. Sodium aurothiomalate inhibited prostaglandin production, although higher concentrations were toxic to macrophages. D-Penicillamine did not affect macrophage prostaglandin production. Colchicine, in contrast, enhanced prostaglandin production at some concentrations. 5 The probable significance of macrophages as a source of prostaglandins, during inflammatory responses, is discussed.

Neutrophil chemotaxis in rheumatoid arthritis. Effect of D-penicillamine, gold salts, and levamisole

The effect of therapeutic concentrations of D-penicillamine, sodium aurothiomalate, and levamisole on in vitro neutrophil chemotaxis and random migration in normal subjects and patients with rheumatoid arthritis was studied. D-penicillamine produced no changes. Sodium aurothiomalate produced dose-related reductions in chemotaxis in normal subjects and in patients who had a good clinical response to gold therapy, while patients who had failed to respond to gold showed a minimal nondose dependent reduction. Levamisole produced dose-dependent stimulation of chemotaxis, a greater effect found with the patients cells. Neutrophil chemotaxis improved to normal values in most patients responding to several months of D-penicillamine treatment but showed an immediate and marked stimulation in patients treated with levamisole.

A double-blind trial of high versus conventional dosages of gold salts for rheumatoid arthritis

In a double-blind study, patients were randomly selected for treatment using conventional doses (CD; 50 mg) or high doses (HD; 150 mg) of sodium aurothiomalate given weekly by injection. Twenty-three patients were assigned to the CD group and 24 to the HD group. Neither efficacy nor toxicity correlated with serum gold concentrations. Conventional doses were as efficacious as high doses with respect to both rapidity and degree of response. However, side effects were much more frequent and severe in the HD group. Thus there is no reason to recommend a 150 mg weekly dosage regimen.

Inhibition of antigen- and mitogen-induced human lymphocyte proliferation by gold compounds

Gold sodium thiomalate (GST) inhibited in vitro antigen- and mitogen-triggered human lymphocyte DNA synthesis. Inhibition of responsiveness was observed with concentrations of GST equivalent to gold levels found in serum or tissues of patients receiving chrysotherapy, Inhibition was dependent upon the gold ion itself since GST and gold chloride were both inhibitory whereas thiomalic acid was not. Inhibition could not be explained by nonspecific killing of cells or by an alteration in the kinetics of the responses. GST inhibited mitogen-induced proliferation most effectively when present from the initiation of culture and could not inhibit the responsiveness of cells which previously had been activated by concanvalin A. These findings indicated that GST blocked a critical early step in lymphocyte activation. The degree of GST-induced inhibition of proliferation was increased in cultures of cells partially depleted of monocytes. Moreover, inhibition was reversed by supplementation of these cultures with purified monocytes. These observations suggested that GST blocked thymus-derived (T)-lymphocyte activation by interfering with a requisite function of the monocyte population in initiating such responses. Prolonged incubation of peripheral blood mononuclear cells with GST resulted in diminished mitogen responsiveness upon subsequent culture in the absence of gold. The addition of fresh monocytes restored responsiveness to these populations. Furthermore, preincubation of purified monocytes with GST rendered them deficient in their ability to support mitogen-induced T-lymphocyte proliferation on subsequent culture. These observations indicate that the major effect of GST results from interference with the functional capability of the monocyte population.

Effects of a gold salt on lymphocyte responses

The effects of sodium aurothiomalate (SATM) on certain lymphocyte functions in vitro were tested. Lymphocytes were obtained from both healthy donors and patients with rheumatoid arthritis (RA). SATM depressed tritiated thymidine uptake in lymphocyte cultures stimulated by phytohaemagglutinin, and in a mixed lymphocyte response assay. Cytotoxic effector cell generation assayed by percentage specific 51Cr release was also depressed by SATM using lymphocytes from healthy donors, and from patients with RA. These effects imply that SATM inhibits both exogenous thymidine uptake, and blastogenesis, and suggest that gold salts may act in RA by interference with T-cell dependent functions.

Effect of aurothiomalate on human mononuclear blood cells cultured in vitro

Human mononuclear phagocytes were exposed to aurothiomalate in various concentrations and at various stages in the differentiation from monocytes to macrophages in vitro. Monocytes exposed to aurothiomalate during the first 90 minutes of culture showed impaired engulfment capacity when tested 8 days after the exposure to the drug. It was found that aurothiomalate suppressed the digestion capacity in differentiated macrophages while the engulfment capacity was unaffected by the drug. During the period of differentiation from 90 minutes to 8 days of culture, exposure to aurothiomalate resulted in a dose dependent reduction in cell survival and differentiation. The effect of aurothiomalate on the blastoid transformation of lymphocytes following BCG stimulation was also tested. A strong and dose dependent inhibition of DNA synthesis was recorded. The inhibition of phagocytosis in mononuclear phagocytes and the inhibition of antigen-induced lymphocyte stimulation as demonstrated may help to explain the effect of aurothiomalate in patients suffering from rheumatoid arthritis.