Albumin metabolism in rheumatoid arthritis

Natural biomimetic nano-system for drug delivery in the treatment of rheumatoid arthritis: a literature review of the last 5 years

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease characterized primarily by synovitis, leading to the destruction of articular cartilage and bone and ultimately resulting in joint deformity, loss of function, and a significant impact on patients' quality of life. Currently, a combination of anti-rheumatic drugs, hormonal drugs, and biologics is used to mitigate disease progression. However, conventional drug therapy has limited bioavailability, and long-term use often leads to drug resistance and toxic side effects. Therefore, exploring new therapeutic approaches for RA is of great clinical importance. Nanodrug delivery systems offer promising solutions to overcome the limitations of conventional drugs. Among them, liposomes, the first nanodrug delivery system to be approved for clinical application and still widely studied, demonstrate the ability to enhance therapeutic efficacy with fewer adverse effects through passive or active targeting mechanisms. In this review, we provide a review of the research progress on the targeting mechanisms of various natural biomimetic nano-delivery systems in RA therapy. Additionally, we predict the development trends and application prospects of these systems, offering new directions for precision treatment of RA.

Unraveling the versatility of human serum albumin - A comprehensive review of its biological significance and therapeutic potential

Human serum albumin (HSA) is a multi-domain macromolecule with diverse ligand binding capability because of its ability to allow allosteric modulation despite being a monomeric protein. Physiologically, HSA act as the primary carrier for various exogenous and endogenous compounds and fatty acids, and alter the pharmacokinetic properties of several drugs. It has antioxidant properties and is utilized therapeutically to improve the drug delivery of pharmacological agents for the treatment of several disorders. The flexibility of albumin in holding various types of drugs coupled with a variety of modifications makes this protein a versatile drug carrier with incalculable potential in therapeutics. This review provides a brief outline of the different structural properties of HSA, and its various binding sites, moreover, an overview of the genetic, biomedical, and allosteric modulation of drugs and drug delivery aspects of HSA is also included, which may be helpful in guiding advanced clinical applications and further research on the therapeutic potential of this extraordinary protein.

Serum albumin, prealbumin, and ischemia-modified albumin levels in patients with ANCA-associated vasculitis: A prospective cohort study

Objectives

Acute phase reactants (APRs) are proteins altered by inflammation and are regarded as surrogate markers representing inflammatory status. This study evaluated changes of albumin (Alb), prealbumin (Palb), and ischemia-modified albumin (IMA) in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) in response to alterations in disease activity and the correlation between disease activity and Alb, Palb, and IMA.

Methods

Fifty-nine patients with AAV registered in the prospective SHAVE cohort, who had available serial blood samples at least three months apart were included (indicated as pre and post). Correlation analysis and linear regression were carried out to determine the relationship between continuous variables. Alb, Palb, and IMA levels in 40 healthy controls (HCs) were compared with patients with AAV.

Results

Comparison of Alb, Palb, and IMA levels in HCs and in patients at initial (pre) and follow-up (post) time points revealed that Alb levels significantly increased following the improvement of disease activity and were comparable between HCs and patients at follow-up (post). Meanwhile, there was no significant difference noted in Palb and IMA levels after the decrease of disease activity. While initial (pre) Alb and Palb were significantly associated with BVAS, a subgroup analysis of patients with new-onset disease showed Palb was no longer significantly associated with Birmingham Vasculitis Activity Score (BVAS). Multivariate linear regression showed Alb level (standardized β = -0.377; 95% confidence interval: -5.623, -1.260; p = 0.003) was an independent predictor of BVAS at baseline.

Conclusions

Among Alb, Palb, and IMA, we found that Alb could be a useful marker indicating disease activity in patients with AAV.

Mutual-reinforcing sonodynamic therapy against Rheumatoid Arthritis based on sparfloxacin sonosensitizer doped concave-cubic rhodium nanozyme

Rheumatoid arthritis (RA) is an autoimmune disease associated with synovitis and cartilage destruction. Ultrasound (US)-driven sonodynamic therapy (SDT) possess a good application prospect in RA therapy because of its non-invasiveness and strong tissue penetration capabilities, which can kill activated synovial inflammatory cells. Nevertheless, the tiny accumulation of sonosensitizers in the joints and the hypoxic synovial microenvironment severely limit the therapeutic effect of SDT. Hence, we developed a sonosensitizer spafloxacin (SPX) doped and human serum albumin (HSA) loaded concave-cubic rhodium (Rh) nanozyme (Rh/SPX-HSA) to realize mutual-reinforcing SDT during ultrasonic activation. On the one hand, SPX would cause mitochondrial dysfunction by inducing excessive reactive oxygen species (ROS) production, thus suppressing fibroblast-like synoviocyte (FLS) under US conditions. On the other hand, concave-cubic rhodium was utilized as a nanozyme with endogenous peroxidase (POD) and catalase (CAT)-like enzyme activities, which not only relieved the hypoxia of the joint to resist angiogenesis, but also enormously ascended the SDT efficacy by rising ¹O₂ levels. Interestingly, the activity of nanozymes was also improved by the ultrasonic cavitation effect, thereby realizing mutual-reinforcing SDT. Overall, our strategy provided Rh-based to achieve effective SDT under hypoxic microenvironment, which offered a promising prospect for highly efficient treatment of RA.

Hyaluronic acid-green tea catechin conjugates as a potential therapeutic agent for rheumatoid arthritis

Fibroblast-like synoviocytes are a key effector cell type involved in the pathogenesis of rheumatoid arthritis. The major green tea catechin, epigallocatechin-3-O-gallate (EGCG), has attracted significant interest for rheumatoid arthritis therapy because of its ability to suppress the proliferation and interleukin-6 secretion of synoviocytes. However, therapeutic efficacy of EGCG has been limited by a lack of target cell specificity. Herein we report hyaluronic acid-EGCG (HA-EGCG) conjugates as an anti-arthritic agent that is capable of targeting fibroblast-like synoviocytes via HA-CD44 interactions. These conjugates exhibited superior anti-proliferative and anti-inflammatory activities compared with EGCG under simulated physiological conditions. Near-infrared fluorescence imaging revealed preferential accumulation of the conjugates at inflamed joints in a collagen-induced arthritis rat model, and their anti-arthritic efficacy was investigated by measuring a change in the edema and histopathological scores. Our findings suggest the potential of HA-EGCG conjugates as an anti-arthritic agent for the treatment of rheumatoid arthritis.

Dietary Fibers (Gum Arabic) Supplementation Modulates Hepatic and Renal Profile Among Rheumatoid Arthritis Patients, Phase II Trial

Background: Rheumatoid arthritis (RA) is an autoimmune disease that mainly affects the synovial joints with systemic manifestations. RA has a major impact on liver and kidney functions as part of the disease pathogenesis or as a sequel of disease medications or, mostly, both of them. The kidney and liver involvement increases the RA morbidity and mortality. Nowadays, dietary interventions are proposed as potential modifiers for disease severity. Gum Arabic (GA) is acacia senegal exudates; it is soluble fiber with prebiotic properties. GA has been discovered to be protective against experimental nephrotoxicity and hepatotoxicity, with comparable findings in human studies. This article addresses the effect of GA on hepatic and renal profile among RA patients.

Methods: Forty patients aged 18–70 received GA daily for 12 weeks as a single dose of 30 g. The liver enzymes, total protein level, serum albumin, serum globulin level, urea, creatinine, and serum electrolytes have been measured as a baseline after 4 weeks and by the end of the study. Cobas C311 (Roche, Germany) automated chemistry analyzer directly determined the values for total protein, albumin, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and creatinine. The study ethically has been approved by the Ethical Committee of the National Medicines and Poisons Board. Trial Registration Identifier: NCT02804581.

Results: Regarding the liver enzymes, GA has significantly decreased the liver enzymes apart from alkaline phosphatase, which showed no significant change. In contrast, GA has increased the serum albumin level with a minor impact on the serum globulin level. Furthermore, GA has also significantly decreased the level of urea (P = 0.0001) and level of Sodium (P = 0.002) with nonsignificant change on creatinine and potassium concentrations.

Conclusion: GA presents hepatic and renal protective effects among RA patients, evidenced by the significant reduction of urea and liver enzymes. Thus, it can be recommended as a dietary supplement for RA patients. Nonetheless, we recommend further investigation to support our findings.

Secreted Protein Acidic and Rich in Cysteine Mediated Biomimetic Delivery of Methotrexate by Albumin-Based Nanomedicines for Rheumatoid Arthritis Therapy

Rheumatoid arthritis (RA) is one of the most common chronic autoimmune diseases. Despite considerable advances in clinical treatment of RA, suboptimal response to therapy and treatment discontinuation are still unresolved challenges due to systemic toxicity. It is of crucial importance to actively target and deliver therapeutic agents to inflamed joints in order to promote in situ activity and decrease systemic toxicity. In this study, we found that SPARC (secreted protein acidic and rich in cysteine) was overexpressed in the synovial fluid and synovium of RA patients as well as mice with collagen-induced arthritis (CIA), which has been scarcely reported. Building upon the SPARC signature of RA joint microenvironment and the intrinsic high affinity of SPARC for albumin, we fabricated methotrexate-loaded human serum albumin nanomedicines (MTX@HSA NMs) and explored them as biomimetic drug delivery systems for RA therapy. Upon intravenous injection of chlorin e6-labeled MTX@HSA NMs into CIA mice, the fluorescence/magnetic resonance dual-modal imaging revealed higher accumulations and longer retention of MTX@HSA NMs in inflamed joints with respect to free MTX molecules. In vivo therapeutic evaluations suggested that the MTX@HSA NMs were able to attenuate the progression of RA with better efficacy and fewer side effects even at half  dose of administrated MTX in comparison with free MTX. By unraveling the mechanism driving the efficient accumulation of MTX@HSA NMs in RA joints and showing their ability to improve the safety and therapeutic efficacy of MTX, our work sheds light on the development of innovative anti-RA nanomedicines with a strong potential for clinical translation.

Serum Trace Element Concentrations in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a condition that is associated with oxidative stress. Serum trace elements and their related transport proteins, e.g., albumin and ceruloplasmin, play an important role in the antioxidant defense. Trace element status may therefore be involved in the pathogenesis of RA or be affected by the disease activity of this chronic inflammatory condition. The study participants were 110 patients with RA and 100 sex- and age-matched healthy volunteers. Serum concentrations of albumin, ceruloplasmin, selenium, zinc, copper, and zinc/copper ratio were measured in all subjects. The relationship between these parameters and disease activity score was also assessed. Lower concentrations of serum Alb, Zn, and Se were independently related to disease activity index. High concentrations of serum copper were associated with the presence of RA. Serum Cu concentrations were positively related to disease activity as assessed by the disease activity score. Low serum concentrations of Zn and Se, and high serum Cu concentrations may be associated with the presence of RA or be a consequence of this condition. Of the trace elements that were investigated in the present study, only serum Cu was positively correlated with disease activity.

A comprehensive review of the neonatal Fc receptor and its application in drug delivery

Advances in the understanding of neonatal Fc receptor (FcRn) biology and function have demonstrated that this receptor, primarily identified for the transfer of passive immunity from mother infant, is involved in several biological and immunological processes. In fact, FcRn is responsible for the long half-life of IgG and albumin in the serum, by creating an intracellular protein reservoir, which is protected from lysosomal degradation and, importantly, trafficked across the cell. Such discovery has led researchers to hypothesize the role for this unique receptor in the controlled delivery of therapeutic agents. A great amount of FcRn-based strategies are already under extensive investigation, in which FcRn reveals to have profound impact on the biodistribution and half-life extension of therapeutic agents. This review summarizes the main findings on FcRn biology, function and distribution throughout different tissues, together with the main advances on the FcRn-based therapeutic opportunities and model systems, which indicate that this receptor is a potential target for therapeutic regimen modification.

Green tea extract improves the oxidative state of the liver and brain in rats with adjuvant-induced arthritis

The purpose of the study was to evaluate the possible effects of the administration of a green tea extract on the oxidative state of the liver and brain of adjuvant-induced arthritic rats, a model for human rheumatoid arthritis. Daily doses of 250 mg kg(-1) (59.8 mg catechins per kg) for 23 days were administered. This treatment produced significant diminutions in protein and lipid damage in liver, brain and plasma. It also diminished the tissue ROS contents and increased the antioxidant capacity of the plasma. The antioxidant defenses, which are diminished by arthritis, were improved by the green tea treatment, as revealed by the restoration of the GSH and protein thiol levels and by the strong tendency for normalizing the activities of the antioxidant enzymes. The activity of glucose 6-phosphate dehydrogenase, which is increased by arthritis in the liver, was also almost normalized by the treatment. In conclusion, it can be said that green tea consumption is possibly beneficial for the liver and brain of patients suffering from rheumatoid arthritis because it attenuates the pronounced oxidative stress that accompanies the disease and, thus, diminishes the injury to lipids and proteins in both liver and brain. There are also indications that, in the liver, the green tea can contribute to normalize the metabolic functions that are substantially modified by arthritis. For example, the green tea normalized the activity of glucose 6-phosphate dehydrogenase, a key enzyme of an important metabolic route (pentose monophosphate pathway). It is expected that the green tea treatment is equally able to normalize the activity of other enzymes (e.g., glucokinase and glucose 6-phosphatase), a hypothesis to be tested by future work.

Development of macromolecular prodrug for rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that is considered to be one of the major public health problems worldwide. The development of therapies that target tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and co-stimulatory pathways that regulate the immune system have revolutionized the care of patients with RA. Despite these advances, many patients continue to experience symptomatic and functional impairment. To address this issue, more recent therapies that have been developed are designed to target intracellular signaling pathways involved in immunoregulation. Though this approach has been encouraging, there have been major challenges with respect to off-target organ side effects and systemic toxicities related to the widespread distribution of these signaling pathways in multiple cell types and tissues. These limitations have led to an increasing interest in the development of strategies for the macromolecularization of anti-rheumatic drugs, which could target them to the inflamed joints. This approach enhances the efficacy of the therapeutic agent with respect to synovial inflammation, while markedly reducing non-target organ adverse side effects. In this manuscript, we provide a comprehensive overview of the rational design and optimization of macromolecular prodrugs for treatment of RA. The superior and the sustained efficacy of the prodrug may be partially attributed to their Extravasation through Leaky Vasculature and subsequent Inflammatory cell-mediated Sequestration (ELVIS) in the arthritic joints. This biologic process provides a plausible mechanism, by which macromolecular prodrugs preferentially target arthritic joints and illustrates the potential benefits of applying this therapeutic strategy to the treatment of other inflammatory diseases.

Beyond the joints in rheumatoid arthritis: Effects of adalimumab on hematologic and lipid indices

Tumor necrosis factor alpha (TNFα) is a multifunctional cytokine which plays a pivotal role in the pathogenesis of rheumatoid arthritis (RA). Apart from its well recognized proinflammatory properties, it is known to interfere with lipid metabolism and erythropoiesis. We evaluated the effects of adalimumab on hematologic, lipid and inflammatory parameters using data from patients on adalimumab 40 mg fortnightly from 2 centers in Malaysia. Mean changes in laboratory values from baseline to Weeks 4, 12 and 24 were compared using paired T test and Wilcoxon signed-rank test. We studied 18 patients with RA who were on adalimumab 40 mg fortnightly. The inflammatory markers i.e. erythrocyte sedimentation rate and C reactive protein showed significant changes as early as at week 4 compared to baseline with p values of 0.003 and 0.005, respectively. From a baseline of high disease activity with a mean Disease Activity Score using 28 joint counts (DAS 28) of 5.3, there was a steady improvement in the disease activity and remission was achieved at week 24 with a DAS 28 of 2.4. The hemoglobin level improved at week 12 (p=0.013) and this was sustained till week 24. As opposed to previous studies, the LDL level significantly decreased at week 12 (p=0.015) and this change persisted till week 24 (p=0.001). The total cholesterol showed a similar pattern as the LDL. The pharmacodynamics of adalimumab therapy in rheumatoid arthritis extend beyond the joints with favorable effects on haemoglobin and lipid profile.

Human serum albumin: from bench to bedside

Human serum albumin (HSA), the most abundant protein in plasma, is a monomeric multi-domain macromolecule, representing the main determinant of plasma oncotic pressure and the main modulator of fluid distribution between body compartments. HSA displays an extraordinary ligand binding capacity, providing a depot and carrier for many endogenous and exogenous compounds. Indeed, HSA represents the main carrier for fatty acids, affects pharmacokinetics of many drugs, provides the metabolic modification of some ligands, renders potential toxins harmless, accounts for most of the anti-oxidant capacity of human plasma, and displays (pseudo-)enzymatic properties. HSA is a valuable biomarker of many diseases, including cancer, rheumatoid arthritis, ischemia, post-menopausal obesity, severe acute graft-versus-host disease, and diseases that need monitoring of the glycemic control. Moreover, HSA is widely used clinically to treat several diseases, including hypovolemia, shock, burns, surgical blood loss, trauma, hemorrhage, cardiopulmonary bypass, acute respiratory distress syndrome, hemodialysis, acute liver failure, chronic liver disease, nutrition support, resuscitation, and hypoalbuminemia. Recently, biotechnological applications of HSA, including implantable biomaterials, surgical adhesives and sealants, biochromatography, ligand trapping, and fusion proteins, have been reported. Here, genetic, biochemical, biomedical, and biotechnological aspects of HSA are reviewed.

Drug targeting systems for inflammatory disease: one for all, all for one

In various systemic disorders, structural changes in the microenvironment of diseased tissues enable both passive and active targeting of therapeutic agents to these tissues. This has led to a number of targeting approaches that enhance the accumulation of drugs in the target tissues, making drug targeting an attractive strategy for the treatment of various diseases. Remarkably, the strategic principles that form the basis of drug targeting are often employed for tumor targeting, while chronic inflammatory diseases appear to draw much less attention. To provide the reader with a general overview of the current status of drug targeting to inflammatory diseases, the passive and active targeting strategies that have been used for the treatment of rheumatoid arthritis (RA) and multiple sclerosis (MS) are discussed. The last part of this review addresses the dualism of platform technology-oriented ("one for all") and disease-oriented drug targeting research ("all for one"), both of which are key elements of effective drug targeting research.

Albumin as a drug carrier: design of prodrugs, drug conjugates and nanoparticles

Albumin is playing an increasing role as a drug carrier in the clinical setting. Principally, three drug delivery technologies can be distinguished: coupling of low-molecular weight drugs to exogenous or endogenous albumin, conjugation with bioactive proteins and encapsulation of drugs into albumin nanoparticles. The accumulation of albumin in solid tumors forms the rationale for developing albumin-based drug delivery systems for tumor targeting. Clinically, a methotrexate-albumin conjugate, an albumin-binding prodrug of doxorubicin, i.e. the (6-maleimido)caproylhydrazone derivative of doxorubicin (DOXO-EMCH), and an albumin paclitaxel nanoparticle (Abraxane) have been evaluated clinically. Abraxane has been approved for treating metastatic breast cancer. An alternative strategy is to bind a therapeutic peptide or protein covalently or physically to albumin to enhance its stability and half-life. This approach has been applied to peptides with antinociceptive, antidiabetes, antitumor or antiviral activity: Levemir, a myristic acid derivative of insulin that binds to the fatty acid binding sites of circulating albumin, has been approved for the treatment of diabetes. Furthermore, Albuferon, a fusion protein of albumin and interferon, is currently being assessed in phase III clinical trials for the treatment of hepatitis C and could become an alternative to pegylated interferon. This review gives an account of the different drug delivery systems which make use of albumin as a drug carrier with a focus on those systems that have reached an advanced stage of preclinical evaluation or that have entered clinical trials.

Formatted anti-tumor necrosis factor alpha VHH proteins derived from camelids show superior potency and targeting to inflamed joints in a murine model of collagen-induced arthritis

OBJECTIVE

The advent of tumor necrosis factor (TNF)-blocking drugs has provided rheumatologists with an effective, but highly expensive, treatment for the management of established rheumatoid arthritis (RA). Our aim was to explore preclinically the application of camelid anti-TNF VHH proteins, which are single-domain antigen binding (VHH) proteins homologous to human immunoglobulin V(H) domains, as TNF antagonists in a mouse model of RA.

METHODS

Llamas were immunized with human and mouse TNF, and antagonistic anti-TNF VHH proteins were isolated and cloned for bacterial production. The resulting anti-TNF VHH proteins were recombinantly linked to yield bivalent mouse and human TNF-specific molecules. To increase the serum half-life and targeting properties, an anti-serum albumin anti-TNF VHH domain was incorporated into the bivalent molecules. The TNF-neutralizing potential was analyzed in vitro. Mouse TNF-specific molecules were tested in a therapeutic protocol in murine collagen-induced arthritis (CIA). Disease progression was evaluated by clinical scoring and histologic evaluation. Targeting properties were evaluated by 99mTc labeling and gamma camera imaging.

RESULTS

The bivalent molecules were up to 500 times more potent than the monovalent molecules. The antagonistic potency of the anti-human TNF VHH proteins exceeded even that of the anti-TNF antibodies infliximab and adalimumab that are used clinically in RA. Incorporation of binding affinity for albumin into the anti-TNF VHH protein significantly prolonged its serum half-life and promoted its targeting to inflamed joints in the murine CIA model of RA. This might explain the excellent therapeutic efficacy observed in vivo.

CONCLUSION

These data suggest that because of the flexibility of their format, camelid anti-TNF VHH proteins can be converted into potent therapeutic agents that can be produced and purified cost-effectively.

Albumin-based drug delivery as novel therapeutic approach for rheumatoid arthritis

We reported recently that albumin is a suitable drug carrier for targeted delivery of methotrexate (MTX) to tumors. Due to pathophysiological conditions in neoplastic tissue, high amounts of albumin accumulate in tumors and are metabolized by malignant cells. MTX, covalently coupled to human serum albumin (MTX-HSA) for cancer treatment, is currently being evaluated in phase II clinical trials. Because synovium of patients with rheumatoid arthritis (RA) shares various features observed also in tumors, albumin-based drug targeting of inflamed joints might be an attractive therapeutic approach. Therefore, the pharmacokinetics of albumin and MTX in a mouse model of arthritis was examined. Additionally, uptake of albumin by synovial fibroblasts of RA patients and the efficacy of MTX and MTX-HSA in arthritic mice were studied. The results show that when compared with MTX, significantly higher amounts of albumin accumulate in inflamed paws, and significantly lower amounts of albumin are found in the liver and the kidneys. The protein is metabolized by human synovial fibroblasts in vitro and in vivo. MTX-HSA was significantly more effective in suppression of the onset of arthritis in mice than was MTX. In conclusion, albumin appears to be a suitable drug carrier in RA, most likely due to effects on synovial fibroblasts, which might increase therapeutic efficacy and reduce side effects of MTX.

An etiologic model proposing that non-insulin-dependent diabetes mellitus is chronic hypoxic stress hyperglycemia

This etiologic model equates non-insulin-dependent diabetes mellitus (NIDDM) to chronic hypoxic stress hyperglycemia produced by increased stimulation of the sympathetic nervous system and hypothalamic-pituitary-adrenal axis. In the initial stages of the disease, hypoxia is believed to result from hemodilutional anemia precipitated by a reduction in vascular smooth muscle tone. The reduction increases lumen diameter necessitating an increased blood volume to maintain pressure. Increased lumen diameter may also trigger atherosclerotic changes that characterize the later stages of NIDDM. The increased diameter decreases the shear stress experienced by endothelial cells and they respond by releasing endothelin, a smooth muscle constrictor and mitogen. The constricting action is hypothesized to be relatively ineffective in NIDDM leading to long-term endothelin release and activation of its mitogenic properties. The resulting increase in the number of smooth muscle cells may explain the intimal thickening of atherosclerosis. Restoration of vascular muscle tone is proposed as a treatment strategy for mild NIDDM.

Swelling of synovial joints - An anatomical, physiological and energy metabolical approach

The direction and part of the rate of fluid filtration between synovial capillary (subscript capill) plasma and joint (subscript j) cavity fluid depends on the hydrostatic (P(capill)-P(j)) and colloid osmotic (COP(plasma)-COP(j)) pressure differences and on the osmotic efficiency (coefficient sigma) of 'colloids' across the barrier between plasma and synovial fluid. The rate of filtration also depends on capillary endothelial hydraulic conductance (L(p)) and surface area (A). Synovial fluid protein is removed by lymphatics, or split to be resorbed or used up by cells. Physiologists put together as equations the above, as well as other terms, all of these influenced by numerous factors. The equations offer a frame for a multifactorial approach to diseases associated with joint swelling and suggest, among others, that in the presence of weak generalized exsudation, synovial joints are loci minores resistentiae to swelling. The influence of joint cartilage energy demands on synovial blood flow may have been underrated. There are many accepted clinical, laboratory and morphological findings that fit this physiological frame that merits further clinical research.

Effect of auranofin on plasma fibronectin, C reactive protein, and albumin levels in arthritic rats

Auranofin, a member of a class of compounds with disease modifying activity, was given to arthritic rats to determine if it could reverse the abnormal plasma concentrations of fibronectin (Fn), C reactive protein (CRP), and albumin, which were unaffected by treatment with non-steroidal anti-inflammatory drugs (NSAIDs). When auranofin was orally administered for two weeks to adjuvant induced arthritic rats it significantly inhibited swelling of the injected and non-injected paws at doses of 3 and 10 mg/kg. Rocket electroimmunoassay measurement of plasma proteins in normal, arthritic, and auranofin treated arthritic rats indicated that auranofin at 10 mg/kg significantly decreased (by 77%) the abnormally high concentration of arthritic rat plasma Fn, though it had no effect on Fn concentrations when administered to normal rats. CRP, which was raised approximately twofold above normal in arthritic rats, was reduced by 56% after treatment of arthritic rats with auranofin at 10 mg/kg, though CRP concentrations in normal rats were unaffected by auranofin treatment. Depressed albumin concentrations in arthritic rats were significantly enhanced (by 30%) by dosing with 10 mg/kg of auranofin. At the 3 mg/kg dose, auranofin did not significantly change plasma concentrations of Fn, CRP, and albumin in arthritic rats. At a dose of 10 mg/kg, however, auranofin, in addition to inhibiting chronic systemic paw inflammation, also altered abnormal concentrations of plasma Fn, CRP, and albumin in the adjuvant arthritic rat, thus distinguishing auranofin from standard NSAIDs we have previously tested.

Malnutrition in rheumatoid arthritis

A nutrition study was conducted in thirty-eight hospitalized rheumatoid arthritis (RA) patients. Twenty-seven (71.1%) had a high likelihood of malnutrition (LOM). Laboratory and anthropometric data suggest that multiple vitamin, calory, and protein deficiencies are present. Age, female sex and a poor grip strength correlated with some indices of malnutrition. Fifteen of 18 patients with a high LOM had a bad outcome whereas 3 of 7 patients with a low LOM had a bad outcome. Malnutrition per se may be a contributing factor to increased morbidity and mortality in RA.

The metabolism of synthetic leukotriene B4 in synovial fluid and whole human blood

The metabolism in vitro of synthetic leukotriene B4 (LTB4) in synovial fluid from rheumatoid arthritis and osteoarthritis patients and in whole blood from these same patient groups and from normal volunteers has been studied. A linear relationship existed between a plot of the time of incubation of samples with LTB4 and the percentage of the initial concentration of LTB4 at each time point. The slope of this line, the rate constant for metabolism, has been used to compare different samples. LTB4 was metabolised more rapidly in the synovial fluid of rheumatoid arthritis patients than osteoarthritis patients. Furthermore, LTB4 was metabolised more rapidly in the blood of rheumatoid arthritis patients than either osteoarthritis patients or normal volunteers. These differences in metabolism correlate with the polymorphonuclear leukocyte (PMN) and albumin content of samples. It is suggested that binding of LTB4 to albumin in vivo will in part determine the available concentration of LTB4 in inflammatory lesions.

Protein binding as a primary determinant of the clinical pharmacokinetic properties of non-steroidal anti-inflammatory drugs

The ability of a wide variety of anionic, cationic, and neutral drugs to bind in a reversible manner to plasma proteins has long been recognised. Non-steroidal anti-inflammatory drugs (NSAIDs) are distinguished as a class by the high degree to which they bind to plasma protein. Plasma protein binding properties are primary determinants of the pharmacokinetic properties of the NSAIDs. Theoretical relationships are reviewed in order to define quantitatively the impact of plasma protein binding on clearance, half-life, apparent volume of distribution, and the duration and intensity of pharmacological effect. The quantitative relationships governing competitive displacement binding interactions are also presented. Experimental methods for in vitro and in vivo determination of the degree of plasma protein binding are discussed. The more common in vitro methods are equilibrium dialysis and ultrafiltration. Methods for characterising the degree of plasma protein binding in vivo consist of either measuring the concentration of drug at equilibrium in an implanted semipermeable vessel or measuring the relative drug concentrations in two body spaces with different protein content. Emphasis is given to the comparative advantages and disadvantages of experimental application of the various in vitro and in vivo methods. Plasma protein binding is discussed as a determinant of the trans-synovial transport of NSAIDs. Trans-synovial transport of NSAIDs appears to be a diffusional process. Limited data in humans receiving ibuprofen, indomethacin, aspirin, carprofen, alclofenac, or diclofenac suggest that clearance of each of these NSAIDs from the synovium is slower than clearance from plasma. The clinical data relevant to the relationship between plasma NSAID concentration and various measures of anti-inflammatory effect are reviewed. A positive correlation between plasma NSAID concentration and anti-inflammatory effect has been observed in only one study on naproxen and one study on piroxicam. In several other studies, the lack of concentration-response correlations is generally attributed to the relatively subjective, quantitatively inexact methods used to assess anti-inflammatory effect and analgesia in arthritic patients, as well as the substantial interpatient variabilities in the fraction of unbound NSAID and the unbound plasma NSAID concentration. In view of the generally poor correlation between concentration and therapeutic response, routine therapeutic monitoring of total plasma NSAID concentration is not recommended as a means of titrating individual dosages to the desired effect in each patient.(ABSTRACT TRUNCATED AT 400 WORDS)

Caeruloplasmin, prealbumin and alpha 2-macroglobulin as potential indices of disease activity in different arthritides

Caeruloplasmin (Cp), prealbumin and alpha 2-macroglobulin (alpha 2-M) concentrations in serum were compared in rheumatoid arthritis (RA), osteoarthrosis, ankylosing spondylitis, psoriatic arthritis, Reiter's syndrome, Behçet's syndrome, SLE and normal controls. Cp was significantly elevated (p less than 0.01) in all disease groups except for Reiter's syndrome and SLE. Prealbumin was only significantly depressed (p less than 0.01) in RA. The most notable elevation in alpha 2-macroglobulin occurred in Reiter's syndrome. However, these differences were generally still within the normal range, and hence these proteins are unlikely to offer alternative indices of disease activity suitable for monitoring the the progress of seronegative arthropathies.

Delayed cutaneous hypersensitivity in rheumatoid arthritis: the influence of nutrition and drug therapy

Significant depression of delayed cutaneous hypersensitivity (DCH) to seven common recall antigens was found in 50 patients with rheumatoid arthritis (RA) compared with 50 matched controls. Complete skin anergy was seen in 12 (24%) of the RA patients but in none of the control subjects. In addition, a nutritional assessment of all subjects tested showed significantly lower serum albumin and body mass indices in the RA compared with the control group. Analysis of these 100 subjects showed a significant correlation (r = 0.53, p less than 0.001) between the number of positive skin reactions and the concentration of serum albumin suggesting an association between nutritional status and DCH. No single factor could be identified to distinguish the reactive and anergic RA patients with the possible exception of drug treatment in that a higher proportion of patients on sodium aurothiomalate or immunosuppressive therapy than D-penicillamine was found in the anergic group. It is likely that the cause of impaired DCH in RA is multifactorial and our findings suggest that drug treatment and nutritional status may be an important contributor to it.

Antirheumatic drug concentrations in human synovial fluid and synovial tissue. Observations on extravascular pharmacokinetics

Antirheumatic drug concentrations have been measured in human synovial fluid and synovial tissue, and provide insights on: (1) extravascular pharmacokinetics; (2) articular pathophysiology; and (3) the factors which modify drug levels in inflamed tissues. Concentrations of free drug in synovial fluid and plasma are the same in all conditions except rheumatoid and infectious arthritis, where the most severely afflicted joints may contain lower synovial fluid drug concentrations. This finding may be relevant to the chronicity and intractability of chronic arthritis. After single-dose therapy and a characteristic 'equilibration time', higher concentrations are found in synovial fluid than in plasma - a phenomenon which results from relative drug sequestration across the trans-synovial diffusion barrier away from the organs of elimination. Studies of oral, parenteral, topical and intra-articular antirheumatic drug therapy are reviewed, and recommendations are made for the conduct of future studies.

Thrombocytosis of active rheumatoid disease

Two cross-sectional and one longitudinal study of patients with rheumatoid arthritis showed that platelet number correlated with both clinical and laboratory parameters of disease activity, including erythrocyte sedimentation rate, zeta sedimentation ratio, viscosity of plasma and blood, white cell count, liver enzymes, rheumatoid factor, and several acute-phase proteins. There was also an inverse relationship between platelet number and the haemoglobin and serum albumin levels. III Indium-labelled platelet survival was reduced in 4 patients with active rheumatoid arthritis despite a raised platelet count, with labelled platelets being localised to inflamed joints in the 2 patients studied. Platelet aggregation was normal. We suggest that the raised platelet count of active rheumatoid arthritis may be a useful index of disease activity and may represent a bone marrow stress (syndrome) response to shortened platelet survival, with platelet sequestration occurring in areas of synovial inflammation.

Protein binding of non-steroidal anti-inflammatory drugs in plasma and synovial fluid of arthritic patients

1 The protein binding of seven non-steroidal anti-inflammatory drugs (indomethacin, tolmetin, salicylic acid, ibuprofen, flurbiprofen, naproxen and GP53,633) and warfarin was investigated by equilibrium dialysis in simultaneous samples of synovial fluid and plasma from 12 arthritic patients. 2 The protein binding of all drugs studied except warfarin and flurbiprofen was significantly lower in synovial fluid than in plasma. 3 The decreased protein binding of these drugs is likely to explain the lower total drug concentrations found in synovial fluid in comparison to plasma. 4 The lower albumin concentration plays an important role in determination of reduced drug binding in synovial fluid compared to plasma and the fatty acid concentration in synovial fluid may also influence the protein binding of some of these drugs.

An analysis of the gastro-intestinal side-effects of non-steroidal anti-inflammatory drugs, with particular reference to comparative studies in man and laboratory species

A critical analysis has been performed of reports published on the incidence of gastro-intestinal (GI) side-effects found in arthritic patients being treated with non-steroid anti-inflammatory (NSAI) drugs. The results show the following: 1. The incidence of GI ulceration (as revealed by gastroscopy) and haemorrhage in arthritic patients taking NSAI drugs may be higher than suspected from clinical trial data. 2. Incidence of all GI side-effects (including ulceration and haemorrhage) may be lower with some of the new NSAI drugs than with traditional drugs (e.g. aspirin, indomethacin and phenylbutazone). 3. Arthritic patients may be more susceptible to the ulcerogenic actions of NSAI drugs. Experiments with animals, together with evidence from clinical studies, indicate that stress factors and the presence of decreased mucosal resistance in the diseased state may contribute to the enhanced susceptibility of the GI tract towards the ulcerogenicity of NSAI drugs. 4. Comparison of data on gastroscopic observations in man with the author's data on the effects of NSAI drugs in stress-sensitized rats shows the latter technique appears to be a useful means of predicting the ulcerogenic potential of NSAI drugs in man. The comparison has also been used to predict the ulcerogenicity of drug - alcohol combinations; alcohol being a common ulcerogen consumed by many patients. Some NSAI drugs with low ulcerogenic activity (i.e. azapropazone, benoxaprofen and fenclofenac) in the stressed-rat assay show little or no interaction with alcohol. These studies using laboratory animals show the importance of employing conditions to mimic environmental factors (e.g. stress and alcohol consumption) which might predispose individuals to ulcerogenic or other side-effects of NSAI drugs. From these studies it appears possible to construct 'predictive profiles' of the relative ulcerogenicity of NSAI drugs which may be applicable to the clinical situation in man.

Auranofin. New oral gold compound for treatment of rheumatoid arthritis

Eight patients with rheumatoid arthritis were treated with SK & F D-39162 (auranofin), a new oral gold compound which was effective in suppressing adjuvant-induced arthritis in rats. Clinical and humoral parameters were studied during a 3-month period of drug administration followed by a 3-month period under placebo. The drug was absorbed, well tolerated, and its action was manifested by a drop in the mean IgG blood levels in the third week of treatment accompanied by clinical improvement after 5 weeks of oral gold intake. Together with IgG changes, an increase of the albumin ratio was observed, as well as a decrease of alpha2-globulin and rheumatoid factor titres. From a total number of 60 swollen joints found initially in the 8 patients only 17 were swollen at week 12 and 9 at week 15. Although the number of patients treated was too small to allow definite conclusions, a follow-up study under placebo of clinical and laboratory changes in the same patients during another 3-month period showed that IgG serum levels rapidly reverted preceding a flare up of disease activity after withdrawal of the drug. This confirmed a direct role in cause-effect relation played by the new oral gold compound.

Assessment of rheumatoid activity based on clinical features and blood and synovial fluid analysis

Joint inflammation in rheumatoid arthritis has been assessed, and the most useful guides to disease activity were determined by analysis of synovial fluid and blood together with the history of joint disability. The patient's own evaluation of the amount of pain suffered was the most useful clinical assessment. Differential cell count and glucose estimations were the most helpful guides in the synovial fluid, while C-reactive protein in the serum most accurately reflected disease activity. The effects of systemic steroids on these indices were studied, and the differences between seronegative and seropositive patients noted.

The influence of drugs and disease activity on biochemical and haematological data in rheumatoid arthritis

Biochemical and haematological data from 218 patients with rheumatoid arthritis were analysed and compared with data from a reference hospital population. The comparison demonstrated significant differences in several biochemical and haematological tests and that the patterns of change are different between males and females. The data were also analysed by conventional statistical methods and discriminant analysis using a computer to establish which tests were most influenced by the activity of the disease and drug therapy. The results obtained demonstrate marked difference between groups of patients with different disease activity or receiving different drugs. The discriminant analysis also identified those tests which differentiate these groups most effectively.

Liver disease in rheumatoid arthritis and Sjøgren's syndrome. Prospective study using biochemical and serological markers of hepatic dysfunction

Inter-relationships of biochemical and immunological tests of liver function have been studied in a prospective study of 216 patients with rheumatoid arthritis (RA), 32 patients with Sjogren's syndrome, and 27 patients with the sicca syndrome, and these results have been compared with those obtained 289 patients with osteoarthrosis or with a form of seronegative polyarthropathy. In general the prevalence of abnormalities in serum alkaline phosphatase, bromsulphthalein excretion, smooth muscle antibody, and mitochondrial antibody in the former three groups was higher than in patients with osteoarthrosis. Patients with Sjogren's syndrome with RA had a higher prevalence of abnormalities of bromsulphthalein excretion, salivary duct antibody than patients with the sicca syndrome. Patients with RA had a higher pervalence of rheumatoid factor than those with the sicca syndrome. Patients with a positive smooth muscle or mitochondrial antibody were found to have a higher prevalence of hepatomegaly and splenomegaly, of abnormal liver function tests, of other autoantibodies, and of histological abnromalitis of liver than those in whom these tests were negative.

Albumin metabolism in fasting, obese subjects

1. Eleven obese subjects fasted for 24 d, by which time their serum albumin concentration had fallen significantly. 125I-labelled albumin was injected on day 7 of fasting to allow study of albumin metabolism.

2. Although no significant alteration occurred in either the intravascular content or the absolute catabolic rate of albumin between days 7 and 24 of fasting, the mean values for both content and catabolic rate were significantly lower than values determined in eight normal subjects.

3. A corresponding fall occurred in the absolute ‘synthesis+transfer’rate.