Immunosuppression by D-penicillamine in vitro. Inhibition of human T lymphocyte proliferation by copper- or ceruloplasmin-dependent generation of hydrogen peroxide and protection by monocytes

Copper homeostasis dysregulation in respiratory diseases: a review of current knowledge

Cu is an essential micronutrient for various physiological processes in almost all human cell types. Given the critical role of Cu in a wide range of cellular processes, the local concentrations of Cu and the cellular distribution of Cu transporter proteins in the lung are essential for maintaining a steady-state internal environment. Dysfunctional Cu metabolism or regulatory pathways can lead to an imbalance in Cu homeostasis in the lungs, affecting both acute and chronic pathological processes. Recent studies have identified a new form of Cu-dependent cell death called cuproptosis, which has generated renewed interest in the role of Cu homeostasis in diseases. Cuproptosis differs from other known cell death pathways. This occurs through the direct binding of Cu ions to lipoylated components of the tricarboxylic acid cycle during mitochondrial respiration, leading to the aggregation of lipoylated proteins and the subsequent downregulation of Fe-S cluster proteins, which causes toxic stress to the proteins and ultimately leads to cell death. Here, we discuss the impact of dysregulated Cu homeostasis on the pathogenesis of various respiratory diseases, including asthma, chronic obstructive pulmonary disease, idiopathic interstitial fibrosis, and lung cancer. We also discuss the therapeutic potential of targeting Cu. This study highlights the intricate interplay between copper, cellular processes, and respiratory health. Copper, while essential, must be carefully regulated to maintain the delicate balance between necessity and toxicity in living organisms. This review highlights the need to further investigate the precise mechanisms of copper interactions with infections and immune inflammation in the context of respiratory diseases and explore the potential of therapeutic strategies for copper, cuproptosis, and other related effects.

Relationship between copper and immunity: The potential role of copper in tumor immunity

Copper is an essential trace element in an organism, and changes in copper levels in vivo often indicate a diseased state. Copper and immunity have been discussed since the last century, with copper deficiency significantly affecting the development and function of the immune system, such as increased host susceptibility to various pathogens, decreased number and impaired function of neutrophils, reduced antibacterial activity of macrophages, decreased proliferation of splenocytes, impaired B cell ability to produce antibodies and impaired function of cytotoxic T lymphocyte and helper T cells. In the past 20 years, some studies have shown that copper ions are related to the development of many tumors, including lung cancer, acute lymphoid leukaemia, multiple myeloma and other tumors, wherein copper ion levels were significantly elevated, and current studies reveal that copper ions are involved in the development, growth and metastasis of tumors through various pathways. Moreover, recent studies have shown that copper ions can regulate the expression of PD-L1, thus, attention should be paid to the important role of copper in tumor immunity. By exploring and studying copper ions and tumor immunity, new insights into tumor immunity could be generated and novel therapeutic approaches to improve the clinical prognosis of patients can be provided.

Role of Copper on Mitochondrial Function and Metabolism

Copper is essential for life processes like energy metabolism, reactive oxygen species detoxification, iron uptake, and signaling in eukaryotic organisms. Mitochondria gather copper for the assembly of cuproenzymes such as the respiratory complex IV, cytochrome c oxidase, and the antioxidant enzyme superoxide dismutase 1. In this regard, copper plays a role in mitochondrial function and signaling involving bioenergetics, dynamics, and mitophagy, which affect cell fate by means of metabolic reprogramming. In mammals, copper homeostasis is tightly regulated by the liver. However, cellular copper levels are tissue specific. Copper imbalances, either overload or deficiency, have been associated with many diseases, including anemia, neutropenia, and thrombocytopenia, as well as tumor development and cancer aggressivity. Consistently, new pharmacological developments have been addressed to reduce or exacerbate copper levels as potential cancer therapies. This review goes over the copper source, distribution, cellular uptake, and its role in mitochondrial function, metabolic reprograming, and cancer biology, linking copper metabolism with the field of regenerative medicine and cancer.

Transferrin Coated d-penicillamine-Au-Cu Nanocluster PLGA Nanocomposite Reverses Hypoxia-Induced EMT and MDR of Triple-Negative Breast Cancers

Triple-negative breast cancer (TNBC), the most aggressive subtype of breast cancer, lacks effective targeted therapies due to negative expression of the targetable bioreceptors. Additionally, hypoxic condition in solid tumors contributes to the epithelial to mesenchymal transition (EMT), which aggravates cancer progression, multidrug resistance (MDR), migration, and stemness of the TNBC. A therapeutic module has been established in this regard by coating PLGA nanoparticle with d-penicillamine templated Au-Cu bimetallic nanoclusters. Further, the resultant nanomaterials were coated with recombinant transferrin protein to specifically target transferrin receptor overexpressing TNBC. The synthesized nanocomposites showed strong orange emission band at 630 nm with fluorescence quantum yield of 2%, rendering it suitable for theranostic applications. Experimental results demonstrated efficient cellular internalization and significant innate anti-cell proliferative potential of the nanocomposites. The fabricated nanocomposites were also able to induce cell death in spheroids, which was confirmed by live/dead dual staining results. Furthermore, when EMT-induced TNBC cells were treated with nanocomposites, they generated reactive oxygen species (ROS), depolarized the mitochondrial membrane potential, and induced apoptosis. Gene expression by real-time PCR indicated that treatment of EMT-induced TNBC cells with nanocomposites facilitated mesenchymal to epithelial transition (MET). In MDA-MB-468 cells, treatment with nanocomposites resulted in a 1.35-fold rise in E-cadherin an epithelial marker and a 1.36-fold decrease in vimentin a mesenchymal marker. Similarly, 2.87-fold and 1.76-fold decrease in stemness markers ALDH1A3 and EpCAM were observed in MDA-MB-231. Furthermore, 4.63-fold decrease in expression of ABCC1, a prominent contributor of MDR, was observed in MDA-MB-231. Protein expression studies revealed that nanocomposites reduced p-STAT-3 by 1.61-fold in MDA-MB-231 and by 7.8-fold in MDA-MB-468. Importantly, nanocomposites downregulated the expression of β-catenin by 3-fold in MDA-MB-231 and by 3.11-fold in MDA-MB-468. Downregulation of EMT with concomitant alteration of STAT-3 and β-catenin signaling pathways led to reduced migration ability of the TNBC cells.

Lysyl oxidase directly contributes to extracellular matrix production and fibrosis in systemic sclerosis

Pulmonary fibrosis is one of the important causes of morbidity and mortality in fibroproliferative disorders such as systemic sclerosis (SSc) and idiopathic pulmonary fibrosis (IPF). Lysyl oxidase (LOX) is a copper-dependent amine oxidase whose primary function is the covalent crosslinking of collagens in the extracellular matrix (ECM). We investigated the role of LOX in the pathophysiology of SSc. LOX mRNA and protein levels were increased in lung fibroblasts of SSc patients compared with healthy controls and IPF patients. In vivo, bleomycin induced LOX mRNA expression in lung tissues, and LOX activity increased in the circulation of mice with pulmonary fibrosis, suggesting that circulating LOX parallels levels in lung tissues. Circulating levels of LOX were reduced upon amelioration of fibrosis with an antifibrotic peptide. LOX induced ECM production at the transcriptional level in lung fibroblasts, human lungs, and human skin maintained in organ culture. In vivo, LOX synergistically exacerbated fibrosis in bleomycin-treated mice. Further, LOX increased the production of interleukin (IL)-6, and the increase was mediated by LOX-induced c-Fos expression, the nuclear localization of c-Fos, and its engagement with the IL-6 promoter region. Our findings demonstrate that LOX expression and activity correlate with fibrosis in vitro, ex vivo, and in vivo. LOX induced ECM production via upregulation of IL-6 and nuclear localization of c-Fos. Thus, LOX has a direct pathogenic role in SSc-associated fibrosis that is independent of its crosslinking function. Our findings also suggest that measuring circulating LOX levels and activity can be used for monitoring response to antifibrotic therapy.

D-penicillamine combined with inhibitors of hydroperoxide metabolism enhances lung and breast cancer cell responses to radiation and carboplatin via H2O2-mediated oxidative stress

D-penicillamine (DPEN), a copper chelator, has been used in the treatment of Wilson's disease, cystinuria, and rheumatoid arthritis. Recent evidence suggests that DPEN in combination with biologically relevant copper (Cu) concentrations generates H2O2 in cancer cell cultures, but the effects of this on cancer cell responses to ionizing radiation and chemotherapy are unknown. Increased steady-state levels of H2O2 were detected in MB231 breast and H1299 lung cancer cells following treatment with DPEN (100µM) and copper sulfate (15µM). Clonogenic survival demonstrated that DPEN-induced cancer cell toxicity was dependent on Cu and was significantly enhanced by depletion of glutathione [using buthionine sulfoximine (BSO)] as well as inhibition of thioredoxin reductase [using Auranofin (Au)] prior to exposure. Treatment with catalase inhibited DPEN toxicity confirming H2O2 as the toxic species. Furthermore, pretreating cancer cells with iron sucrose enhanced DPEN toxicity while treating with deferoxamine, an Fe chelator that inhibits redox cycling, inhibited DPEN toxicity. Importantly, DPEN also demonstrated selective toxicity in human breast and lung cancer cells, relative to normal untransformed human lung or mammary epithelial cells and enhanced cancer cell killing when combined with ionizing radiation or carboplatin. Consistent with the selective cancer cell toxicity, normal untransformed human lung epithelial cells had significantly lower labile iron pools than lung cancer cells. These results support the hypothesis that DPEN mediates selective cancer cell killing as well as radio-chemo-sensitization by a mechanism involving metal ion catalyzed H2O2-mediated oxidative stress and suggest that DPEN could be repurposed as an adjuvant in conventional cancer therapy.

Improvement of spontaneous locomotor activity with JAK inhibition by JTE-052 in rat adjuvant-induced arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a chronic inflammatory disease that leads to joint destruction, disability, and decreased quality of life (QOL). Inhibition of Janus kinase (JAK) signaling ameliorates articular inflammation and joint destruction in animal models of RA, but its effects on behaviors indicating well-being are poorly understood. In this study, we evaluated the effect of JAK inhibition on spontaneous locomotor activity in rats with adjuvant-induced arthritis, a rodent model of RA.

METHODS

Arthritis was induced in male Lewis rats by a single subcutaneous injection of Freund's complete adjuvant. The novel JAK inhibitor JTE-052 was orally administered for 7 days after the onset of arthritis.

RESULTS

Induction of arthritis suppressed the spontaneous locomotor activity of the rats. Administration of JTE-052 completely improved the spontaneous locomotor activity, with partial reductions in articular inflammation and joint destruction. Hyperalgesia and motor functions were also improved, but the efficacy was not complete. However, serum interleukin (IL)-6 levels were completely decreased at 4 h after administration of the first dose of JTE-052.

CONCLUSIONS

This study demonstrated that JAK inhibition improved the spontaneous locomotor activity of rats with adjuvant-induced arthritis, in association with amelioration of pain and physical dysfunction as a consequence of suppression of joint inflammation. Moreover, although further studies are needed, there was possible participation of IL-6 downregulation in the improvement of locomotor activity by JAK inhibition.

Patients with systemic sclerosis present increased DNA damage differentially associated with DNA repair gene polymorphisms

OBJECTIVE

Patients with systemic sclerosis (SSc) exhibit increased toxicity when exposed to genotoxic agents. In our study, we evaluated DNA damage and polymorphic sites in 2 DNA repair genes (XRCC1 Arg399Gln and XRCC4 Ile401Thr) in patients with SSc.

METHODS

A total of 177 patients were studied for DNA repair gene polymorphisms. Fifty-six of them were also evaluated for DNA damage in peripheral blood cells using the comet assay.

RESULTS

Compared to controls, the patients as a whole or stratified into major clinical variants (limited or diffuse skin involvement), irrespective of the underlying treatment schedule, exhibited increased DNA damage. XRCC1 (rs: 25487) and XRCC4 (rs: 28360135) allele and genotype frequencies observed in patients with SSc were not significantly different from those observed in controls; however, the XRCC1 Arg399Gln allele was associated with increased DNA damage only in healthy controls and the XRCC4 Ile401Thr allele was associated with increased DNA damage in both patients and controls. Further, the XRCC1 Arg399Gln allele was associated with the presence of antinuclear antibody and anticentromere antibody. No association was observed between these DNA repair gene polymorphic sites and clinical features of patients with SSc.

CONCLUSION

These results corroborate the presence of genomic instability in SSc peripheral blood cells, as evaluated by increased DNA damage, and show that polymorphic sites of the XRCC1 and XRCC4 DNA repair genes may differentially influence DNA damage and the development of autoantibodies.

D-penicillamine and other low molecular weight thiols: review of anticancer effects and related mechanisms

Low molecular weight thiols (LMWTs) like N-acetyl cysteine, D-penicillamine, captopril, Disulfiram and Amifostine, etc. have been used as chemo-preventive agents. Recent studies have reported cell growth inhibition and cytotoxicity in several different types of cancer cells following treatment with several LMWTs. Cytotoxic and cytostatic effects of LMWTs may involve interaction of the thiol group with cellular lipids, proteins, intermediates or enzymes. Some of the mechanisms that have been proposed include a p53 mediated apoptosis, thiyl radical induced DNA damage, membrane damage through lipid peroxidation, anti-angiogenic effects induced by inhibition of matrix metalloproteinase enzymes and angiostatin generation. LMWTs are strong chelators of transition metals like copper, nickel, zinc, iron and cobalt and may cause metal co-factor depletion resulting in cytotoxicity. Oxidation of thiol group can also generate cytotoxic reactive oxygen species (ROS).

Cytotoxicity of D-penicillamine in association with several heavy metals against cultured rabbit articular chondrocytes

The potentiation or antagonistic effects of Cu, Hg, Pb and Cd salts in the presence of a long-acting anti-rheumatic drug, D-penicillamine (D.P.) were studied on cultured chondrocytes. CuSO(4) (10(-4)M), HgCl(2) (10(-5)M), Pb(CH(3)COO)(2) (10(-3)M) and D.P. (10(-3)M) when used alone caused a small decrease in cell proliferation. The addition of D.P. with Cu, Hg or Pb salts resulted in a marked increase in the extent of growth inhibition. In contrast, CdCl(2) (10(-5)M) produced an important growth inhibitory effect, and D.P. antagonized CdCl(2) action. The CuSO(4) D.P. toxicity was probably due to production of H(2)O(2) in situ. To verify this hypothesis, catalase, responsible for H(2)O(2) metabolism was used, and was found to partially reverse the inhibitory effect of CuSO(4)-D.P.

A retrospective randomly selected cohort study of D-penicillamine treatment in rapidly progressive diffuse cutaneous systemic sclerosis of recent onset

BACKGROUND

Several uncontrolled studies in systemic sclerosis have shown that D-penicillamine may cause improvement in skin sclerosis, decrease the rate of new visceral organ involvement, and improve overall survival.

OBJECTIVES

To undertake a single-centre retrospective randomly selected cohort study to examine the effects of D-penicillamine treatment on skin and visceral organ involvement in patients with rapidly progressive systemic sclerosis of recent onset.

METHODS

Eighty-four patients with diffuse cutaneous systemic sclerosis who had received D-penicillamine within 24 months of clinically detectable onset of skin sclerosis were randomly selected from the systemic sclerosis cohort followed at the Scleroderma Center of Thomas Jefferson University. Employing a previously described severity scale, disease severity and skin involvement were compared from initiation of D-penicillamine to end of study and a correlated matched t-test was used to establish statistical significance.

RESULTS

At a mean+/-SD duration of D-penicillamine therapy of 29.2+/-5.5 months and at a median dose of 750 mg per day statistically significant improvement in skin (P<0.01) and cardiac, pulmonary and renal involvement (P<0.05) was observed. At last follow-up, 17 (20%) patients were still receiving D-penicillamine, 25 (30%) had discontinued it owing to disease improvement, and 18 (21%) had discontinued it owing to side-effects.

CONCLUSIONS

In a population of patients with diffuse cutaneous systemic sclerosis, with progressive disease of recent onset, D-penicillamine treatment at a median dose of 750 mg per day caused a statistically significant reduction in skin involvement and improvement of renal, cardiac and pulmonary involvement.

An investigation into copper catalyzed D-penicillamine oxidation and subsequent hydrogen peroxide generation

D-Penicillamine is a potent copper (Cu) chelating agent. D-Pen reduces Cu(II) to Cu(I) in the process of chelation while at the same time being oxidized to D-penicillamine disulfide. It has been proposed that hydrogen peroxide is generated during this process. However, definitive experimental proof that hydrogen peroxide is generated remains lacking. Thus, the major aims of these studies were to confirm and quantitatively assess the in vitro production of hydrogen peroxide during copper catalyzed D-penicillamine oxidation. The potential cytotoxic effect of hydrogen peroxide generation was also investigated in vitro against MCF-7 human breast cancer cells. Cell cytotoxicity resulting from the incubation of D-penicillamine with copper was compared to that of D-penicillamine, copper and hydrogen peroxide. The mechanism of copper catalyzed D-penicillamine oxidation and simultaneous hydrogen peroxide production was investigated as a function of time, concentration of cupric sulfate or ferric chloride, temperature, pH, anaerobic condition and chelators such as ethylenediaminetetraacetic acid and bathocuproinedisulfonic acid. A simple, sensitive and rapid HPLC assay was developed to simultaneously detect D-penicillamine, its major oxidation product D-penicillamine disulfide, and hydrogen peroxide in a single run. Hydrogen peroxide was shown to be generated in a concentration dependent manner as a result of D-penicillamine oxidation in the presence of cupric sulfate. Chelators such as ethylenediaminetetraacetic acid and bathocuproinedisulfonic acid were able to inhibit D-penicillamine oxidation. The incubation of MCF-7 human breast cancer cells with D-penicillamine plus cupric sulfate resulted in the production of reactive oxygen species within the cell and cytotoxicity that was comparable to free hydrogen peroxide.

Characterization of a multicopper oxidase gene from Staphylococcus aureus

A multicopper oxidase gene from Staphylococcus aureus was cloned and overexpressed. Purified recombinant multicopper oxidase oxidized the substrate 3,3'-dimethoxybenzidine in the presence of copper. Disruption of mco showed copper sensitivity and H(2)O(2) resistance, suggesting roles for mco in copper homeostasis and oxidative stress response. Northern blot analysis showed copper-induced mco transcription.

Synthesis and evaluation of long-acting D-penicillamine derivatives

This study extends the use of two lathyrogens, ss-aminopropionitrile (BAPN) and D-penicillamine (DPA) from daily systemic or local-topical administration to long-time acting agents. This was achieved by converting the hydrophilic drugs into lipophilic derivatives. The synthesis of functional derivatives of DPA consisted in esterification with methyl-, hexyl-, or benzyl alcohols in the presence of thionylchloride. The esters formed were hydrochlorides, acidic and soluble in water. During neutralization in vitro or in vivo by tissue fluid, an oily substance is formed that elutes from a hydrogel polymer at a much slower rate than hydroplilic DPA itself. The degree of lipophilicity, measured as a partition coefficient between octanol/water, was highest for hexyl ester and lowest for methyl ester DPA. A single injection of either DPA hexyl ester HCl or 3-hexyl(amino) propionitrile into the full thickness skin incision wound in rats significantly lowered the breaking strength of the wound 12 days after injection, indicating the interference with collagen cross-linking. Both agents injected into the breast adenocarcinoma in Fisher rats significantly inhibited tumor growth without any signs of local or systemic toxicity. We conclude that these lipophilic lathyrogens with prolonged effectiveness are suitable in the treatment of pathologies, consisting of excessively cross-linked or deposited collagen (fibrotic adhesions, strictures, stenosis, and scar contractures) and in the treatment of single, solitary tumors, malignant and benign.

Treatment of chronic haemophilic synovitis in humans with D-penicillamine

Chronic proliferative synovitis secondary to haemathroses is a major complication in patients with severe haemophilia. Current management strategies include prophylactic infusions of the missing coagulation factor, corticosteroids, synoviorthesis and/or synovectomy with variable degrees of benefit. In addition, patients with coagulation factor inhibitors are not amenable to the invasive therapeutic modalities. The gross and microscopic findings of the synovitis in haemophilic arthritis are remarkably similar to those seen in patients with rheumatoid arthritis, although the pathophysiology of these two conditions are quite different. Haemophilic arthropathy, in the later stages, resembles degenerative rather than inflammatory joint disease. Oral D-penicillamine, a drug effective in the proliferative synovitis of rheumatoid arthritis, was evaluated in 16 patients. Ten patients had an unequivocal response, while three had a reduction in palpable synovium and three had no response. Thus 81% of the patients had a beneficial response. Minor reversible drug side-effects occurred in two patients (proteinuria in one and a rash in the second). The results of this study suggest that D-penicillamine is an effective and safe drug for the treatment of haemophilic chronic synovitis.

Immunotoxicity of cupravit and previcur fungicides in mice

Female mice received either cupravit or previcur at dose levels of 300 ppm and 1000 ppm, respectively, for 8 weeks. Humoral immune response was evaluated by measuring the plaque-forming cell (PFC) response and hemolysing antibody titers against sheep red blood cells (SRBCs), a T lymphocyte-dependent antigen. In addition, the hemagglutinating antibody titers against Escherichia coli lipopolysaccharide (LPS), a T cell-independent antigen, were determined. Both cupravit and previcur suppressed the PFC response by 74% and 78% of control values, respectively. The primary hemolysin antibody titers were reduced to 62% and 76% of control values, respectively. The hemagglutinating antibody titers were decreased to 66% and 77% of control values, respectively. Memory function was reduced as evidenced by inhibition of secondary hemolysin titers to SRBCs. Cell-mediated immunity was inhibited by both cupravit and previcur as evidenced by reduced delayed-type hypersensitivity (DTH) reaction to tuberculin to 77% and 76% of control values, respectively. Decreases in total leukocytic and lymphocytic counts were recorded together with histopathological changes in spleen and thymus gland of intoxicated animals.

Dietary vitamin E and T cell-mediated function in the elderly: effectiveness and mechanism of action

One of the most dramatic and consequence-bearing age-related phenomena is the decline of the immune function with old age. Age-related T cell-mediated immunity dysfunction has been implicated in the etiology of many of the chronic degenerative diseases of the elderly, including arthritis, cancer, autoimmune diseases and increased susceptibility to infectious diseases. T cells from aged individuals are impaired in their response to mitogens and in their cytokine production. In recent years, several studies have emphasized the importance of intracellular anti-oxidant levels for preserving the immune function. Recent progress in understanding the mechanisms of action of anti-oxidants on cellular metabolism, have shown that anti-oxidants may modulate signal transduction and gene expression in immune cells. Vitamin E is widely recognized as a major lipid-soluble chain-breaking anti-oxidant in the biological membrane, where it scavenges free radicals, inhibiting the initiation and chain propagation of lipid peroxidation and protecting cellular structures against oxidative stress damage. Experimental studies have provided evidences for a role of vitamin E in protecting the immune system of elderly subjects. This article reviews the studies concerning the effect of both vitamin E deficiency and supplementation on T cell-mediated immune function in aging. Following a chronological pathway, the present article will also discuss the knowledge regarding the underlying mechanism of action of vitamin E.

Purification and characterization of NAD:Penicillamine ADP transferase from Bacillus sphaericus. A novel NAD-dependent enzyme catalyzing phosphoramide bond formation

A strain of Bacillus sphaericus isolated from a local soil sample has been found to use beta,beta-dimethyl-DL-cysteine (DL-penicillamine) as the sole nitrogen source. Crude cell extract of the bacterium showed potent penicillamine-consuming activity only in the presence of NAD, which, however, was not used as an electron acceptor. Characterization of reaction products revealed that penicillamine was derivatized to a phosphoramide adduct with the ADP moiety of NAD, whereas the nicotinamide-ribose group was released and hydrolyzed spontaneously to ribose and nicotinamide. The phosphoramide product, ADP-penicillamine, caused potent product inhibition on the purified enzyme, and adenylate deaminase was found to be effective in converting the inhibitory product into inosine-diphosphate-penicillamine and thereby maintained the catalysis for several hours. The novel enzyme, termed as NAD:penicillamine ADP transferase, showed a single band on SDS-polyacrylamide gel electrophoresis with a mass of approximately 42 kDa. The native enzyme was monomeric. The enzyme showed high substrate specificity to NAD (Km = 13.0 mM) and L-penicillamine (Km = 6.5 mM); other nucleotides such as NADP, NAD(P)H, AMP, ADP, and ADP-ribose did not substitute for NAD, and L-valine, L-cysteine, L-homocysteine, L-cystine, L-leucine, and L-isoleucine did not serve as the substrate. Kinetic studies suggested an Ordered Bi Bi mechanism, with NAD as the first substrate to bind and ADP-L-penicillamine as the last product released. The novel NAD-dependent enzyme may catalyze the first step in penicillamine degradation in the strain of B. sphaericus.

Pharmacological effects of SA96 (bucillamine) and its metabolites as immunomodulating drugs--the disulfide structure of SA-96 metabolites plays a critical role in the pharmacological action of the drug

SA96 (generic name, bucillamine) is a disease-modifying anti-rheumatoid arthritis (RA) drug with immunological effects. This compounds has two sulfhydryl groups in its molecule, and the differences and similarities between this drug and D-penicillamine, which is also a sulfhydryl group-containing anti-rheumatic drug, have frequently been discussed. To clarify the pharmacological differences between these two drugs, we examined the concentrations of the compounds and its metabolites in serum and synovial fluid, paying special attention to the metabolites of SA96 produced in vivo. SA96 was metabolized in a very short time to SA981 which is a disulfide compound formed by intramolecular binding of two sulfhydryl groups, and transferred to synovial fluid. In addition SA981 had significant suppressive effects on IL-6 and IL-8 production by synovial cells in vitro. These results demonstrate that SA96, which has two sulfhydryl groups, exhibits anti-rheumatic effects via a pharmacological action clearly different from that of D-penicillamine.

DNA damage and mutation: contributors to the age-related alterations in T cell-mediated immune responses?

The genetic material of our cells is susceptible to damage by a wide variety of extrinsic and intrinsic entities. The amount of genetic damage accumulated in vivo will depend upon an individual's ability to defend against and/or repair DNA damage. T cells in vivo have been shown to accumulate DNA damage and mutations over time. The accumulation of such genetic damage will occur in T cells possessing a 'naive' or a 'memory' phenotype. Since T cells are required to undergo extensive clonal expansion upon antigenic stimulation, DNA damage and mutations may result in: a failure of T cells to proliferate, because of DNA damage-mediated cell cycle arrest; decreased rates of proliferation, as a consequence of selection in vivo against cells carrying certain mutations and/or apoptosis, triggered by critical levels of DNA damage. Thus, when T cells, containing critical levels of genetic damage, are required to undergo rapid clonal expansion in the presence of antigen, insufficient numbers of T cells may be produced and so the immune response would be sub-optimal. In this paper the possible contribution of DNA damage and/or mutation to the age-related alterations in T cell-mediated immune responses will be discussed.

Inhibition of drug-naive and -resistant leukemia cell proliferation by low molecular weight thiols

The aim of these studies was to investigate the ability of cysteamine and its congeners to arrest the proliferation of leukemic cells and to determine the physico-chemical properties responsible for this ability. Fifteen low molecular weight thiol-bearing compounds were shown to arrest the proliferation of CCRF-CEM cells and a methotrexate-resistant subline, with IC50 values between 10(-5) and 10(-4) M. Cysteamine arrested proliferation by slowing the passage of cells through S phase. These cells subsequently resumed cycling, although a proportion went on to die by apoptosis. The antiproliferative action of cysteamine was shown to depend, in part, on H2O2 production. This ability to generate peroxide is shared by many thiol compounds, and molecular modeling indicated that thiol groups were required for the antiproliferative actions of the congeners of cysteamine. Molecular modeling also revealed that the most efficacious antiproliferative agents were those that had their amino acid and thiol moieties separated by an intramolecular distance of 3.17 to 5.9 A, as exemplified by WR 1065 and the aminothiophenols. These findings indicate that thiol-bearing compounds may have some efficacy in the treatment of drug-naive and -resistant leukemia cells.

The effects of cyclosporin A, dexamethasone and other immunomodulatory drugs on induced expression of IL-3, IL-4 and IL-8 mRNA in a human mast cell line

We examined by RT-PCR the effect of a number of immunomodulatory compounds on cytokine gene expression at the level of mRNA in the HMC-1 human leukemic mast cell line. Resting cells expressed relatively low constitutive levels of mRNA for the cytokine genes IL-3, IL-4 and IL-8, and mRNA levels for each of these cytokines were significantly enhanced after 4-h stimulation with the calcium ionophore ionomycin. Treatment of the cells with the immunosuppressant CsA at 10(-5) M produced a significant inhibition of ionomycin-induced expression of IL-3, IL-4 and IL-8 mRNA, and at 10(-6) M produced a significant inhibition of induced expression of IL-3 and IL-8 but not IL-4. At both concentrations of CsA, expression of IL-3 was inhibited to a greater extent than that of the other two cytokines. Treatment of the cells with the corticosteroid DEX at 10(-5) M but not 10(-6) M significantly reduced the ionomycin-induced expression of IL-3 but not IL-4 or IL-8 mRNA. Progesterone and methotrexate were both inactive in modulation of induced cytokine expression in this cell line. In conclusion, this study shows that cytokine expression, particularly of IL-3, is inhibited in a human mast cell line by CsA and DEX. These findings may be relevant to the anti-allergic action of these drugs.

Alterations in intracellular reactive oxygen species generation and redox potential modulate mast cell function

The administration of mercuric chloride (HgCl2), gold compounds, or D-penicillamine to Brown Norway (BN) rats causes a T helper (Th)2 cell-associated autoimmune syndrome characterized by the production of a number of autoantibodies, marked elevation of serum IgE concentration, and tissue injury in the form of a vasculitis and arthritis. We have recently shown that the same compounds in vitro sensitize BN rat peritoneal mast cells for IgE-triggered mediator release and interleukin-4 mRNA production. We wished to test the hypothesis that these agents influence mast cell function via an effect on intracellular reactive oxygen species (ROS) production/redox balance. Mast cells were obtained from BN rats by peritoneal washout. Incubation with HgCl2, gold compounds or D-penicillamine (the latter only in the presence of copper ions) led to the intracellular production of ROS as shown by the oxidative production of the fluorescent compound 2',7'-dichlorofluorescein. Mast cells were more sensitive than splenocytes to this effect. Direct oxidative stress (exposure to H2O2) produced a similar sensitization for mediator release to that caused by HgCl2. Inhibition of ROS formation by desferrioxamine or catalase diminished the enhancement of IgE-mediated serotonin release caused by HgCl2, as did replenishment of intracellular glutathione. 2-Mercaptoethanol exacerbated the toxicity of HgCl2, perhaps due to the formation of a lipophilic complex that enhanced HgCl2 uptake. Blocking of glutathione synthesis increased the toxicity of HgCl2, but also abolished any sensitizing effect on mediator release. These results support three main predictions of our hypothesis: (1) the compounds known to influence mast cell function all lead to the generation of ROS within the mast cell; (2) direct oxidative stress causes sensitization for mediator release by the mast cell; and (3) modulation of ROS production/redox balance within the mast cell modulates the effects of these compounds on mast cell function. The balance of oxidative/antioxidative influences may play an important role in the modulation of mast cell function, particularly in the context of chemically induced autoimmunity.

Epstein-Barr virus clonality in lymphomas occurring in patients with rheumatoid arthritis

OBJECTIVE

A causative role for Epstein-Barr virus (EBV) in the development of lymphoma in patients with rheumatoid arthritis (RA) has been proposed. We investigated the molecular features of EBV-positive diffuse large cell lymphomas in 2 patients with RA.

METHODS

Southern blot analysis for immunoglobulin gene rearrangements, terminal repeat analysis for clonality of the EBV genome, and double-labeling of the lymphoma cells by in situ hybridization and immunoperoxidase staining were performed.

RESULTS

In both cases, double-labeling studies localized the EBV genome to the malignant B cells. Both neoplasms contained clonal immunoglobulin gene rearrangements and clonal EBV genomes.

CONCLUSION

Our data indicate that EBV infection was an early step in the development of these neoplasms. The findings further extend knowledge on the similarity of this subset of lymphomas to posttransplantation lymphomas and emphasize the role of immunosuppression in their genesis.

Disease-modifying antirheumatic drugs. Potential effects in older patients

Disease-modifying antirheumatic drugs (DMARDs) are frequently used in rheumatoid arthritis. A number of physiological changes occur in the elderly which may modify the use of these medications. The most commonly used DMARDs are antimalarial drugs (particularly hydroxychloroquine), sulfasalazine and methotrexate. The principal mechanism of action of the antimalarials relates to the fact that they change intracellular pH, which downregulates numerous immune functions. Hydroxychloroquine is metabolised to 3 metabolites and has a very low clearance. It is moderately effective in dosages up to 6.4 mg/kg/day. While it is not the most effective of the DMARDs, it is the least toxic. Sulfasalazine is a prodrug which is enzymatically split in the bowel to form sulfapyridine (the principal active metabolite) and 5-aminosalicylic acid. The metabolism of sulfasalazine is complex and, to some extent, genetically determined. The mechanism of action of the drug is not well understood, but involves decreased production of cytokines and decreased proliferative response of lymphocytes. It may slow the rate of bony damage associated with rheumatoid arthritis. Nearly 50% of the patients who are prescribed sulfasalazine continue to receive the drug for up to 4 years. Sulfasalazine is not as well tolerated as hydroxychloroquine. Gastrointestinal toxicity, in particular, seems to be a problem in elderly patients taking this medication. Methotrexate is presently the most popular of the DMARDs for the treatment of rheumatoid arthritis. Methotrexate inhibits dihydrofolate reductase and adenosine release and has a secondary effect on cytokines and polymorphonuclear chemotaxis. It is highly metabolised within cells and remains there for prolonged periods. Up to 70% of patients who are prescribed methotrexate continue treatment for 5 years. Methotrexate treatment is associated with gastrointestinal, hepatic, cutaneous and, possibly, pulmonary adverse effects. The use of azathioprine, penicillamine and gold compounds is briefly reviewed in this article. Elderly patients have an increased incidence of rashes when using penicillamine, relative to young patients. There are no age-related differences in the efficacy and tolerability of azathioprine or gold therapy. The poor absorption and renal toxicity associated with cyclosporin, the new 'salvage' therapy in rheumatoid arthritis, make it generally unsuitable for use in the elderly, except under specialists' supervision.

Innovative treatment approaches for rheumatoid arthritis. Combination therapy

It is accepted that combination DMARD therapy is a useful tool in current rheumatological practice. However, well-designed, large, long-term, controlled clinical trials are needed to determine which combinations, dosage schedules, and sequences of administration are most beneficial and least toxic. Until we develop treatment regimens that reliably induce and sustain acceptable control of disease manifestations in all patients for the rest of their natural lifespan, daily oral prednisone will continue to be a troublesome component of 'bridge' therapy, as it becomes the sole surviving constant in complex regimens whose other components are eventually discontinued because of toxicity, lack of efficacy, or non-compliance. We have often seen patients in whom the replacement of a well-tolerated but presumable ineffective DMARD with another DMARD has led to worsening of disease, when the modest benefits of the discontinued DMARD were lost before the hoped for onset of benefit from its replacement became evident. Since the toxicity of combinations of DMARDs has not appeared to be excessive, one can reasonably add the second DMARD to the first, while carefully monitoring for adverse effects and planning ton continue the combination until increased benefit occurs. Subsequently, if the second DMARD is not tolerated, the partial benefit from the first has not been given up, and a longer duration of treatment with the initial DMARD is sometimes associated with satisfactory improvement. If better control of rheumatoid arthritis is evident after 3-6 months of treatment with the combination of DMARDs, one must still decide whether to stop the first DMARD, stop the second, or continue with the combination. In the absence of major toxicity, we are most likely to choose to continue the combination if the patient has had a good response, thus inadvertently embarking on prolonged combined DMARD therapy (Paulus, 1990). Of course, other drugs besides those discussed above are available to control different aspects of joint damage; they should be considered in any combination therapy. Drugs which potentially protect cartilage from damage, such as orgotein, glycosaminoglycan polysulphate (Arteparon), and Rumalon, may prove useful in rheumatoid arthritis; they have been studied in osteoarthritis, but there is evidence that they protect cartilage from breakdown by inflammation in some animal models. As one of the many goals of treatment in rheumatoid arthritis is to protect cartilage, these chondroprotective agents might also be considered as part of the combinations to be studied. The combination of modest clinical efficacy with minimal toxicity reported with minocycline treatment of rheumatoid arthritis make this another potentially interesting addition to combination therapy regimens (Tilley et al, 1995). It is also important to continue the development of so-called 'biological agents', such as interleukin-2 receptor antibodies, anti-CD4 antibodies, anti-TNF-alpha agents and anti-thymocyte globulin. Combinations which include such agents have not yet been evaluated, although is seems logical considering that these agents offer the possibility of precise intervention directed at specific steps of the immuno-inflammatory process; their combination may thus be more effective than the use of single agents alone. While we await results of well-designed studies of these newer agents in RA therapy, we should continue to consider creative ways of using drugs that are already available.

Immunopathogenesis and immunotherapy in rheumatoid arthritis: an area in transition

In years to come, new therapeutic modalities for the treatment of chronic arthritis will be launched for general clinical use. These therapies, until today only used in clinical studies, are based on knowledge obtained from animal models of chronic arthritis. This knowledge not only ushers therapeutic use in humans: in many settings, the animal studies have proven to be irreplacable tools to get insights into the pathogenesis of chronic arthritis. Rheumatoid arthritis (RA) shows a strong linkage of susceptibility to a certain epitope common to some HLA-DR beta chains; this immunogenetic linkage is the strongest evidence for specific, T-cell dependent immunity in the pathogenesis of the disease. Despite intense efforts, no unequivocal proofs of T-cell specificity or oligoclonality have been found in RA. Therapeutic efforts directed against T-cells or T-cell functions have also at the best showed partial effects. As compared to the local production of T-cell cytokines in the joint, monokine production is abundant. Therapies aimed at neutralizing the effects of the cartilage-devastating monokine TNF-a have showed remarkable results in small clinical trials. The possibility of increasing the presence of the regulatory cytokines IL-4, IL-10 and TGF-beta has also been explored, but only in animal studies. Immunology has also shed light on the mode of action of the commonly used 'disease modifying' drugs, and combinations of such drugs have shown increased potentials in recent clinical studies. The possibility of combining traditional anti-arthritic drugs with recent immunological tools seem promising for the future. This review discusses recent advances in the understanding of pathogenesis and delineate new therapeutic approaches for chronic arthritis from the point of view of the immunologically oriented clinician.

Compounds that induce autoimmunity in the brown Norway rat sensitize mast cells for mediator release and interleukin-4 expression

Brown Norway (BN) rats given mercuric chloride (HgCl2), gold (Au) salts or D-penicillamine develop a T helper 2 (Th2) cell-mediated autoimmune syndrome. The recent observation of tissue injury within 24 h of HgCl2 treatment suggested the involvement of a non-T cell. We therefore examined the effect of these compounds on rat mast cells in vitro. Incubation of BN rat peritoneal mast cells with HgCl2 enhanced the release of serotonin in response to IgE cross-linking agents. Mast cells from Lewis rats, a strain not susceptible to the autoimmune syndrome in vivo, were affected to a lesser extent. The effect was observed with purified BN mast cells, suggesting a direct action. Similar effects were seen with D-penicillamine in the presence of copper ions, a combination that produces hydrogen peroxide, and Au. HgCl2 caused significant induction of interleukin (IL)-4 mRNA in mast cells from BN, but not Lewis rats. The data demonstrate a novel enhancing effect of a number of compounds on mast cell mediator release, and an inducing effect of HgCl2 on mast cell IL-4, expression. These findings are consistent with our hypotheses that mast cells may contribute to early tissue injury, and also, via production of IL-4, may initiate and/or augment, the Th2 response in the BN rat model of chemical-induced autoimmunity.

Protective effects of D-penicillamine and a thiazole derivative, SM-8849, on pristane-induced arthritis in mice

To evaluate the antiarthritic properties of a novel thiazole derivative, the drugs SM-8849, D-penicillamine and indomethacin were administered to pristane-injected DBA/1 mice. The mice were treated daily with the agents for 32 weeks, starting from the day of the pristane injection. Treatment with SM-8849 (50 mg/kg) resulted in an amelioration of arthritic disease, as assessed by clinical, radiographic, and histologic examinations. Similar results were obtained in mice treated with 50 mg/kg D-penicillamine, although this disease modifying antirheumatic drug was slightly less effective than the same dose of SM-8849. In contrast, indomethacin at the maximum tolerated dose of 2 mg/kg did not alter the course of the disease. SM-8849 and D-penicillamine were also shown to reduce serum levels of rheumatoid factors and the acute-phase reactant, serum amyloid P component. Indomethacin failed to affect either parameter. Flow cytometric analysis revealed an elevation in the T-cell population that expressed CD44, a marker of murine memory T-cells, in spleens from pristane-injected mice. SM-8849, but not D-penicillamine, prevented the increase in this cell population. These results led us to conclude that pristine-induced arthritis was a useful model for the evaluation of antirheumatic agents, in that using this model, we were able to distinguish disease modifying antirheumatic drugs from nonsteroidal anti-inflammatory drugs. Our findings also indicate that SM-8849 shows antiarthritic activity, with a unique mechanism of action, differing from that of D-penicillamine.

Oxidative stress as a mediator of apoptosis

Many agents which induce apoptosis are either oxidants or stimulators of cellular oxidative metabolism. Conversely, many inhibitors of apoptosis have antioxidant activities or enhance cellular antioxidant defenses. Mammalian cells exist in a state of oxidative siege in which survival requires an appropriate balance of oxidants and antioxidants. Thomas Buttke and Paul Sandstrom suggest that eukaryotic cells may benefit from this perilous existence by invoking oxidative stress as a common mediator of apoptosis.

Inhibition of mitogen-induced response of human peripheral blood mononuclear cells by bucillamine, a new antirheumatic sulfhydryl drug

The mechanism of action of bucillamine, [N-(2-mercapto-2-methylpropionyl)-L-cysteine] (BC), a novel antirheumatic drug that is used in patients with rheumatoid arthritis (RA), was compared with that of D-penicillamine (DP). BC inhibited phytohemagglutinin (PHA)-induced DNA synthesis of peripheral blood mononuclear cells (PBMCs) in a dose-dependent manner, and this inhibition occurred both in the presence and absence of copper, whereas DP-induced inhibition required the presence of cupric ions. Significant inhibition of DNA synthesis was observed at a BC concentration of 10 micrograms/ml. The disulfide form of BC, but not DP disulfide, suppressed the proliferation of PBMCs. After preincubation of human peripheral blood T lymphocytes or Møs with BC or DP, these cells were combined and the overall PHA response was estimated. Inhibition of the PHA response was observed following pretreatment of either T lymphocytes or Møs with BC, whereas inhibition was attained only when T lymphocytes were pretreated with DP and copper. As sulfhydryl agents produce hydrogen peroxide in the presence of cupric ions, the effect of catalase on DP- and BC-induced inhibition of PBMC DNA synthesis was examined. Catalase partially reversed the BC-induced inhibition of DNA synthesis of PBMCs, and it restored the inhibition by DP and copper almost to the control level. These results suggest that BC suppresses the function of both T lymphocytes and Møs in the mitogen response of PBMCs, whereas the action of DP is targeted at T lymphocytes.

Formation of DNA strand breaks by D-penicillamine and bucillamine in human lymphocytes

DNA strand breakage by D-penicillamine and bucillamine, anti-rheumatic agents with thiol residues was evaluated in DNA unwinding assays. When incubating human peripheral blood lymphocytes with D-penicillamine or bucillamine in the presence of 8 microM CuSO4, numerous DNA strand breaks occurred and those depended on the production of hydrogen peroxide and were completely blocked in the presence of catalase. This phenomenon was reversible, and fragmented DNA was repaired in 8 to 24 h. Significant decreases in cellular NAD levels were observed at concentrations of D-penicillamine or bucillamine which could damage DNA. As extensive depletion of cellular NAD functionally inactivates lymphocytes, the formation of DNA strand breaks may have a role in the immunomodulating action of these anti-rheumatic drugs.

Increased oxygen tensions modulate the cellular composition of the adaptive immune system in BALB/c mice

In acute and chronic experiments, each of eight groups of young mice were assigned separately to different pressures of oxygen to which it was to be exposed. Lymphocytes from spleen, thymus, and peripheral blood were analyzed following oxygen exposure. Subset populations changed depending on the oxygen tension. Blood lymphocyte populations reflected lymphocyte changes in thymus or spleen. Thus, a full understanding of the pharmacological effects of hyperbaric oxygen, requires a knowledge of simultaneous effects of increased oxygen pressures on the various compartments comprising the immune system.

Copper deficiency reversibly impairs DNA synthesis in activated T lymphocytes by limiting interleukin 2 activity

The essentiality of adequate copper (Cu) nutriture for normal T-cell function in laboratory and domestic animals is well established. However, specific biochemical roles of Cu in the maturation and activation of T cells have not been defined. Previous work showed that when cultures of splenic mononuclear cells (MNCs) from Cu-deficient rats were exposed to T-cell mitogens, DNA synthesis was markedly reduced despite normal up-regulation of interleukin 2 (IL-2) receptors, transferrin receptors, and class II major histocompatibility complex molecules. In the present study, IL-2 activity in PHA-treated cultures of MNCs from Cu-deficient rats was 40-50% that of controls as determined by bioassay. Addition of rat IL-2 to phytohemagglutinin-treated cultures of MNCs from Cu-deficient rats increased blastogenic activity to control levels, demonstrating that Cu deficiency does not inhibit transition of quiescent cells to the competence phase of the activation process. Moreover, supplementation of MNC cultures from Cu-deficient rats with physiological levels of Cu enhanced IL-2 activity and DNA synthesis in response to phytohemagglutinin. These data indicate that IL-2 activity in cultures of activated splenic T lymphocytes from Cu-deficient rats is insufficient for optimal blastogenesis.

Increased DNA strand breaks in mononuclear cells from patients with rheumatoid arthritis

Immune dysfunction is linked with lymphocyte DNA metabolism. In particular, DNA damage may impair lymphocyte function and induce increased cell turnover; such changes are of relevance to the pathogenesis of rheumatoid arthritis. The rate of DNA unwinding in alkaline solution was used as a measure of the number of DNA strand breaks in mononuclear cells freshly isolated from peripheral blood. The rate of DNA unwinding was significantly increased in cells from patients with rheumatoid arthritis compared with those from healthy subjects and from patients with other autoimmune and connective tissue diseases. These findings support the hypothesis that DNA damage is increased in patients with rheumatoid arthritis and it is one factor contributing to immune dysfunction in this disease.

Augmented IgG anti-acetylcholine receptor response following chronic penicillamine administration

A model of D-penicillamine (DP) induced myasthenia gravis (MG) was developed in which the anti-acetylcholine receptor (anti-AChR) antibody response to AChR challenge was increased in mice chronically treated with DP. To investigate the mechanism of the DP induced increase, IgM and IgG anti-AChR responses to AChR challenge were studied. IgG responses were significantly greater in the DP treated mice than in the control group while IgM responses were not significantly different. This change appeared to be relatively specific for the AChR response because neither serum immunoglobulin levels nor the IgG response to a second antigen (purified protein derivative) were increased by DP treatment. These results suggest that a specific sensitization to AChR occurs during chronic DP treatment.

In vitro mechanism of oxidation of D-penicillamine in plasma

D-Penicillamine (P-SH) added to plasma in-vitro is transformed rapidly to low molecular weight (LMW) disulfides and smaller amounts of D-penicillamine:protein conjugate. The P-SH loss through transformation is accompanied by a quantitatively similar decline in the total sulfhydryl group concentration in plasma solutions. Therefore, P-SH disappearance is predominantly through oxidation, rather than thioldisulfide interchange with plasma disulfides. The rate of P-SH transformation is dependent on the albumin concentration. It is not influenced, however, by the concentration of reduced sulfhydryl groups on plasma protein, since transformation occurs at an unattenuated rate in solutions of sulfhydryl-blocked plasma protein. D-Penicillamine:protein disulfides, therefore, are not important intermediates in P-SH oxidation in vitro. Trace amounts of transitional metals bind loosely to plasma albumin in vivo. The rate of P-SH oxidation in albumin solutions from which transitional metals have been removed is a mean of 68% of the rate in untreated solutions. Restoring [Cu2+] in treated albumin solutions to physiological levels restores the rate of P-SH oxidation. The rate of P-SH disappearance from albumin solutions correlates with [Cu2+] over a range of albumin concentrations. Catalysis of P-SH oxidation by physiological concentrations of albumin-associated Cu2+ therefore contributes to the disappearance of P-SH from plasma in vitro. A similar phenomenon may occur in vivo.

CuSO4 as an inhibitor of B cell proliferation

In the course of investigating the mechanisms of the in vitro immunosuppressive effect of D-penicillamine in the presence of copper ion with murine spleen cells, we observed that copper ion, by itself, exhibited a strong immunosuppressive effect at a low concentration. Namely, the addition of CuSO4 at a concentration of 0.1 to 2 microM markedly inhibited the development of SRBC-specific plaque forming cells (PFC) without causing cytotoxicity. CuSO4, at the same concentration range, suppressed the lipopolysaccharide (LPS)-induced proliferative response, but not the response induced by concanavalin A (Con A). The suppressive effect of CuSO4 on the antibody production was reversed by 500 U/ml of catalase, but that on the LPS-induced proliferative response was not. CuSO4 also substantially suppressed the pokeweed mitogen-induced proliferative response. These findings suggest that CuSO4 acts as an inhibitor of B cell proliferation and, through this effect, markedly inhibits the antibody production in murine spleen cells.

D-penicillamine

D-Pen represents an effective treatment for a proportion of patients with RA and PSS. Its status in the treatment of juvenile RA is uncertain. The best results will be obtained by a skillful, careful physician maintaining careful surveillance for toxicity. Neither the mode of action nor the mechanisms of toxicity are well understood in RA. Consequently, safer and more effective analogues of D-pen have not been produced.

D-penicillamine metabolism: the role of transformation in blood plasma

The transformation of D-penicillamine (D-pen) was studied in orally- and intravenously-dosed rats and in human plasma in vitro. In each case, low molecular weight (LMW) metabolites (previously identified as disulphides) and a mixed disulphide between D-pen and albumin (D-pen-protein) formed. The rates of D-pen elimination, other than through protein conjugation, were comparable in the rat groups to the rate of oxidation to LMW metabolites in vitro. The rates of transformation to D-pen-protein were also comparable in the in vitro preparations and in orally-treated rats. These qualitative and quantitative similarities suggest blood plasma may be an important site of transformation in vivo. Extracellular oxidation of D-pen may be linked to its antirheumatic action, either through reduction of oxygen species or through formation of D-pen-protein disulphides at surfaces of mononuclear leukocytes.

D-penicillamine and D-penicillamine-protein disulphide in plasma and synovial fluid of patients with rheumatoid arthritis

1. The plasma pharmacokinetics of D-penicillamine (D-pen) and D-penicillamine-albumin disulphide (D-pen-alb) were examined over a dosage interval in six patients with rheumatoid arthritis. In two of these, 24 h synovial fluid profiles of D-pen and D-pen-alb were also obtained. 2. D-pen was undetectable in plasma at the beginning of the study. The peak concentration (5.4 +/- 1.2 microM) occurred at between 45 min and 2 h and the mean elimination half-life was 0.6 h. D-pen-alb, however, was present at a mean plasma concentration of 19.1 microM prior to dosage, peaked at 26.2 microM and was eliminated with a half-life of 40 h. 3. D-pen concentrations in synovial fluid rose more slowly and peaked lower than in plasma. D-pen-alb was present in synovial fluid of the patients at 50.1% and 83.6%, respectively, of the simultaneous plasma concentration prior to dosage. Concentrations varied during the study interval, corresponding to changes in plasma concentrations. 4. These results demonstrate that D-pen forms stable conjugates with protein in treated patients. The presence of D-pen-alb in relatively high concentrations throughout the dosage interval contrasts with the low concentrations and rapid elimination of D-pen. Both D-pen and D-pen-alb were also shown to be present at the putative site of drug action (the inflamed synovial joint) in concentrations lower than those in plasma.

Activation pathways of synovial T lymphocytes. Expression and function of the UM4D4/CDw60 antigen

Accumulating evidence implicates a central role for synovial T cells in the pathogenesis of rheumatoid arthritis, but the activation pathways that drive proliferation and effector function of these cells are not known. We have recently generated a novel monoclonal antibody against a rheumatoid synovial T cell line that recognizes an antigen termed UM4D4 (CDw60). This antigen is expressed on a minority of peripheral blood T cells, and represents the surface component of a distinct pathway of human T cell activation. The current studies were performed to examine the expression and function of UM4D4 on T cells obtained from synovial fluid and synovial membranes of patients with rheumatoid arthritis and other forms of inflammatory joint disease. The UM4D4 antigen is expressed at high surface density on about three-fourths of synovial fluid T cells and on a small subset of synovial fluid natural killer cells; in synovial tissue it is present on more than 90% of T cells in lymphoid aggregates, and on approximately 50% of T cells in stromal infiltrates In addition, UM4D4 is expressed in synovial tissue on a previously undescribed population of HLA-DR/DP-negative non-T cells with a dendritic morphology. Anti-UM4D4 was co-mitogenic for both RA and non-RA synovial fluid mononuclear cells, and induced IL-2 receptor expression. The UM4D4/CDw60 antigen may represent a functional activation pathway for synovial compartment T cells, which could play an important role in the pathogenesis of inflammatory arthritis.

Differences in the effects of the antirheumatic drugs, bucillamine and D-penicillamine, on mitogen-induced proliferation of mouse spleen cells

The effect of bucillamine [N-(2-mercapto-2-methylpropionyl)-L-cysteine], a new antirheumatic drug, on the concanavalin A (Con A)-induced proliferation of mouse spleen cells was compared with the effect of D-penicillamine (D-pen). Bucillamine inhibited the Con A-induced incorporation of thymidine (TdR) into mouse spleen cells in a dose-dependent fashion. At the concentration of 10(-4) M, bucillamine inhibited the incorporation by approximately 80%. The inhibitory effect of bucillamine was not enhanced by the addition of copper. In contrast, D-pen showed the same degree of inhibition only in the presence of copper. (4R)-7,7-Dimethyl-6-oxo-tetrahydro-3H-1,2,5-dithiazepine-4-carboxy lic acid (SA981), an intramolecular disulfide derivative of bucillamine, also showed the same degree of inhibition as bucillamine in the absence and presence of copper, whereas D-penicillamine disulfide did not show the inhibitory effect even in the presence of copper. The inhibitory effects of bucillamine and SA981 were not abolished significantly by the addition of catalase which restored the inhibition by D-pen plus copper. The mechanism of inhibition by D-pen plus copper is believed to involve the production of hydrogen peroxide resulting from the oxidation of D-pen. The results in this study, however, indicated that the inhibitory effect of bucillamine is not due to the production of hydrogen peroxide.

Oxidants, joint inflammation and anti-inflammatory strategies

In summary, we support the hypothesis that the rheumatoid knee is subjected to repeated hypoxic reperfusion injury. Moreover, we speculate that oxidative damage induced as a consequence of hypoxic reperfusion injury leads to the synthesis of intracellular stress proteins. In certain individuals this triggers an autoimmune response which might explain the persistance of the rheumatoid disease process. This gives scope for novel therapeutic approaches in the future development of anti-inflammatory agents.

Inhibition of human endothelial cell proliferation in vitro and neovascularization in vivo by D-penicillamine

To investigate the effects of D-penicillamine (D-Pen) on angiogenesis, we have studied the effects of this drug on in vitro proliferation of human endothelial cells (EC) and in vivo corneal neovascularization. D-Pen, in the presence of copper sulfate, suppressed tritiated thymidine ([3H]TdR) incorporation into EC in a dose-dependent manner. Significant inhibition was observed with D-Pen concentrations attainable in the serum and tissues of treated patients. Neither D-Pen nor copper ion alone significantly affected [3H]TdR incorporation into EC. The inhibition by D-Pen and copper was blocked by catalase (CAT) or horseradish peroxidase but not by boiled CAT or SOD. When rabbits were daily injected intravenously with D-Pen at the per kilogram dosage administered to rheumatoid patients, neovascularization as quantitated by the proliferation of corneal new blood vessels was significantly inhibited. These results suggest that hydrogen peroxide generated by D-Pen and copper exerts a pronounced antiangiogenic effect through inhibition of EC proliferation. It is, therefore, considered that D-Pen may suppress rheumatoid synovitis by reducing the number of small blood vessels available for the emigration of chronic inflammatory cells, and the proliferation of the synovial tissue.