Newer immunosuppressive drugs: their potential role in rheumatoid arthritis therapy

Mechanistic target of rapamycin (mTOR): a potential new therapeutic target for rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by systemic synovitis and bone destruction. Proinflammatory cytokines activate pathways of immune-mediated inflammation, which aggravates RA. The mechanistic target of rapamycin (mTOR) signaling pathway associated with RA connects immune and metabolic signals, which regulates immune cell proliferation and differentiation, macrophage polarization and migration, antigen presentation, and synovial cell activation. Therefore, therapy strategies targeting mTOR have become an important direction of current RA treatment research. In the current review, we summarize the biological functions of mTOR, its regulatory effects on inflammation, and the curative effects of mTOR inhibitors in RA, thus providing references for the development of RA therapeutic targets and new drugs.

Panaxynol induces fibroblast-like synovial cell apoptosis, inhibits proliferation and invasion through TLR4/NF-κB pathway to alleviate rheumatoid arthritis

BACKGROUND AND PURPOSE

Panaxynol (PAL, PubChem CID: 5281149) is a common natural minor component in Umbelliferae plants, such as Radix Saposhnikoviae Divaricatae. Modern pharmacology studies show that PAL has nutritional value and anti-inflammatory and other pharmaceutical activities. Therefore, the scientific hypothesis of PAL in the treatment of rheumatoid arthritis was put forward, and the hypothesis was further verified by Fibroblast-like synovial cells (RA-FLS) and Collagen Induced Arthritis (CIA) rats models.

EXPERIMENTAL METHOD

CIA method was used to establish a rat arthritis model. After extracting RA-FLS, flow cytometry and immunofluorescence were used to explore the effect of PAL on the apoptosis and proliferation of RA-FLS. Wound healing and transwell experiment explored the effect of PAL on the migration and invasion of RA-FLS. Western blot analysis explored the inner mechanism of the effect of PAL on RA-FLS. At the same time, it also explored the role of PAL in CIA rats, including pathological section detection and western blot analysis.

MAIN RESULTS

PAL can promote the apoptosis and inhibit the proliferation, migration and invasion of RA-FLS. PAL can also reduce joint swelling in CIA rats, reduce pannus formation and inflammatory infiltration in the joints. Western blot analysis showed that PAL mainly played a role through the TLR4/NF-κB signaling pathway.

CONCLUSION

The results of in vivo and in vitro experiments show that PAL can effectively alleviate the condition of RA, and may be a potential drug for the treatment of RA.

Burden of rheumatoid arthritis on patients' work productivity and quality of life

BACKGROUND

To determine the burden of Rheumatoid Arthritis (RA) on patients' work productivity and health related quality of life (HRQoL), and examine the influence of several exposure variables; to analyze the progression of RA over 1 year and its impact on work productivity and HRQoL.

METHODS

International multicenter prospective survey including patients in 18 centers in Argentina, Brazil, Colombia and Mexico with diagnosis of RA and aged between 21-55 years. The following standard questionnaires were completed at baseline and throughout a 1-year follow-up: WPAI:RA, WALS, WLQ-25, EQ-5D-3 L and SF-36. Clinical and demographic variables were also collected through interview.

RESULTS

The study enrolled 290 patients on baseline visit. Overall mean scores at baseline visit were: WPAI:RA (presenteeism) = 29.5% (SD = 28.8%); WPAI:RA (absenteeism) = 9.0% (SD = 23.2%); WPAI:RA (absenteeism and presenteeism) = 8.6% (SD = 22.6%); WALS = 9.0 (SD = 6.1); WLQ-25 = 7.0% (SD = 5.1%); SF-36 Physical Scale = 39.1 (SD = 10.3) and Mental Scale = 45.4 (SD = 11.3); EQ-5D-3 L VAS = 69.8 (SD = 20.4) and EQ-5D-3 L index = 0.67 (SD = 0.23). Higher educational levels were associated with better results in WLQ-25, while previous orthopedic surgeries reduced absenteeism results of WPAI:RA and work limitations in WLQ-25. Higher disease duration was associated with decreased HRQoL. Intensification of disease activity was associated with decreased work productivity and HRQoL, except in WLQ-25. In the longitudinal analysis, worsening in disease activity was associated with a decrease in both work productivity and HRQoL.

CONCLUSIONS

RA patients are dealing with workplace disabilities and limitations and loss in HRQoL, and multiple factors seems to be associated with this. Worsening of disease activity further decreased work productivity and HRQoL, stressing the importance of disease tight control.

Update on immununosuppressive therapies for dogs and cats

Treatment of immune-mediated disease in dogs and cats continues to evolve as new therapies are introduced or adapted from human medicine. Glucocorticoids remain the first-line therapy for many of the immune-mediated or inflammatory diseases of cats and dogs. The focus of this article is to provide an update on some of the common immunosuppressive therapies used in small animal veterinary medicine. The goals of therapy are to induce disease remission through the inhibition of inflammation and the modulation of lymphocyte function.

SKLB023 blocks joint inflammation and cartilage destruction in arthritis models via suppression of nuclear factor-kappa B activation in macrophage

Rheumatoid arthritis (RA) is the most common arthritis and is mainly characterized by symmetric polyarticular joint disorders. Our previous study demonstrated a novel small molecule compound (Z)-N-(3-Chlorophenyl)-2-(4-((2,4-dioxothiazolidin-5-ylidene) methyl) phenoxy) acet-amide (SKLB023) showed potently anti-arthritic effects in a rat arthritis model, however, the underlying mechanisms for this are largely unknown. Both NF-κB and macrophages were reported to play important roles in the pathologic processes of RA. The purposes of this study were to indicate whether NF-κB and macrophages contributed to anti-arthritic effects of SKLB023 in two experimental arthritis models. Our results showed that SKLB023 could significantly improve joint inflammation and cartilage destruction both in adjuvant induced arthritis (AIA) and collagen-induced arthritis (CIA) models. We further found that the binding activation of NF-κB to DNA in joint tissues and RAW264.7 macrophages were suppressed by SKLB023. SKLB023 also inhibited the NF-κB activity in peritoneal macrophages by luciferase assay. Furthermore, the number of macrophages in synovial tissues was decreased after the treatment of different doses of SKLB023. The levels of TNF-α, IL-1β, and IL-6 in plasma, and the levels of TNF-α, NO, and IL-1β in peritoneal macrophages were down-regulated by SKLB023. Finally, SKLB023 attenuated the expression of iNOS and COX-2 in vivo and suppressed the phosphorylations of components of the mitogen-activated protein kinases (MAPKs). These observations identify a novel function for SKLB023 as an inhibitor of NF-κB in macrophages of RA, highlighting that SKLB023 was a potential therapeutic strategy for RA.

Dentritic cell derived IL-18 production is inhibited by rapamycin and sanglifehrin A, but not cyclosporine A

Interleukin-18 (IL-18), a product of dendritic cells (DC), is a pro-inflammatory cytokine involved in the pathogenesis of allograft rejection, vascular disease, arthritis and diabetes. Rapamycin (Rapa) is an immunosuppressant that inhibits T cell mTOR kinase activation. In contrast, Sanglifehrin A (SFA), is a cyclophilin-binding immunosuppressant that does not act on calcineurin phosphatases but appears to inhibit IL-2-dependent T cell proliferation. Rapa and SFA exert some immunosuppressive effects on DC by inhibiting IL-12 production, although their effects on DC have not been investigated as comprehensively as those on T cells. We aimed to determine the impact of these drugs on DC IL-18 synthesis in vivo and in vitro. We found in vivo that LPS-stimulated OX62(+) DC produced significantly more IL-18 mRNA, compared to OX62(+) DC depleted splenocytes (p<0.01) and non-LPS-stimulated OX62(+) DC (p<0.01). OX62(+)CD4(+) and OX62(+)CD4(-) cells produced similar amounts of IL-18 mRNA. Rapa and SFA, but not CsA, significantly inhibited IL-18 production from OX62(+) DC in vitro, in a dose-dependent manner (p<0.05). In vivo IL-18 production was also inhibited by Rapa and SFA in splenic OX62(+) DC (p<0.01). Finally, inhibition of IL-18 production by Rapa and SFA was independent of the FK506 or cyclophilin pathways, respectively. In conclusion, Rapa and SFA, but not CsA, block IL-18 production and this novel Rapa blockade effect on IL-18 may contribute to the ability of Rapa to inhibit chronic allograft nephropathy and restenosis.

Sirolimus-related pulmonary toxicity mimicking 'asthma like' symptoms

Sirolimus is an immunosuppressant with expanding use in pediatric organ transplantation, dermatology and rheumatology. We report two cases of children who developed asthma like symptoms and were diagnosed with interstitial lung disease, which responded to discontinuation of sirolimus. Pediatricians should be aware about the pulmonary side effects of sirolimus.

Adalimumab for rheumatoid arthritis

In the last few years significant advances have been made in our understanding of the molecular mechanisms underlying rheumatoid arthritis pathogenesis. Pro-inflammatory cytokines, such as TNF-alpha, play a pivotal role in its pathogenesis. Anti-TNF-alpha biological agents are considered a major advance in the treatment of rheumatoid arthritis. Adalimumab is a fully human monoclonal antibody that binds specifically to TNF-alpha, thereby neutralising its activity. It had significant efficacy in well-designed, placebo-controlled trials in patients suffering from rheumatoid arthritis, both as monotherapy and in combination with various disease-modifying antirheumatic drugs, including methotrexate. Adalimumab was generally well tolerated during both concomitant therapy with methotrexate or standard antirheumatic therapy and monotherapy. In addition, the radiographic progression of structural joint damage was significantly inhibited by adalimumab and improved quality of life. This review summarises the recent available data.

Cellular pharmacodynamics of immunosuppressive drugs for individualized medicine

The therapeutic effects of immunosuppressive drugs are known to deviate largely between patients, but efficient strategies for the differentiation of patients who show clinical resistance to immunosuppressive therapies have not been established. Accordingly, a considerable number of patients receive treatment with immunosuppressive drugs despite the onset of serious side effects and poor responses. Cellular pharmacodynamics of immunosuppressive drugs in vitro using peripheral lymphocytes derived from each patient, an attractive way to distinguish resistant patients, is respected and has been applied to the carrying out of individualized immunosuppressive therapy. In this article, I summarize experimental procedures for assaying immune cell responses to immunosuppressive drugs in vitro, and highlight the relationship between cellular sensitivity to immunosuppressive drugs and the therapeutic efficacy of drugs in organ transplantation and several immunological disorders. I will also overview the molecular mechanisms and genetic bases for cellular and clinical resistance to immunosuppressive drugs. Lastly, the future clinical prospects for the application of in vitro drug sensitivity tests for "patient-tailored" immunosuppressive therapies are discussed.

Comparative bioavailability of the microemulsion formulation of cyclosporine (Neoral) with a generic dispersion formulation (Cicloral) in young healthy male volunteers

The aim of this study was to compare the bioavailability of cyclosporine (CyA) from the generic dispersion formulation Cicloral (CIC) with the microemulsion formulation Neoral (NEO) and the original Sandimmune (SIM) capsules after single doses of 100, 300, or 600 mg of drug, respectively. The study was performed according to an open 3-period cross-over design with 12 young healthy male volunteers for each dosage. The concentrations of CyA and its main metabolites were determined by high performance liquid chromatography in whole blood and urine up to 48 hours postdosing. Peak concentrations and area under the time-concentration curve were greater for the NEO and CIC formulations compared with SIM, and the mean bioavailability of CIC was significantly (P<0.05) lower compared with NEO. The bioavailability of SIM compared with NEO was 54% to 71%, in agreement with previous results. Bioequivalence was not demonstrated between CIC (test) and NEO (reference) as the 90% confidence intervals were outside the 80% to 125% guidelines based on log-transformed AUCs, and were 75.2% to 87.7% at 100 mg, 79.2% to 91.8% at 300 mg, and 76.6% to 94.5% at 600 mg doses. The respective values for Cmax were 78.9% to 94.6%, 80.7% to 95.0%, and 71.4% to 84.1%. A good correlation was demonstrated between the urinary recovery of CyA and the AUC4. Therefore, the urinary recovery of CyA may be helpful as a surrogate parameter for the systemic exposure of patients to CyA. Whereas the relative amount of hydroxylated metabolites (AM1, AM9, AM1c) was similar for all formulations and doses, the urinary recovery of the N-demethylated metabolite AM4N decreased with increasing dose indicating saturable metabolism. No relationship could be demonstrated between CYP3A activity using dextromethorphan as a probe for the metabolic clearance of CyA.

Rapamycin improves lymphoproliferative disease in murine autoimmune lymphoproliferative syndrome (ALPS)

Autoimmune lymphoproliferative syndrome (ALPS) is a disorder of abnormal lymphocyte survival caused by defective Fas-mediated apoptosis, leading to lymphadenopathy, hepatosplenomegaly, and an increased number of double-negative T cells (DNTs). Treatment options for patients with ALPS are limited. Rapamycin has been shown to induce apoptosis in normal and malignant lymphocytes. Since ALPS is caused by defective lymphocyte apoptosis, we hypothesized that rapamycin would be effective in treating ALPS. We tested this hypothesis using rapamycin in murine models of ALPS. We followed treatment response with serial assessment of DNTs by flow cytometry in blood and lymphoid tissue, by serial monitoring of lymph node and spleen size with ultrasonography, and by enzyme-linked immunosorbent assay (ELISA) for anti-double-stranded DNA (dsDNA) antibodies. Three-dimensional ultrasound measurements in the mice correlated to actual tissue measurements at death (r = .9648). We found a dramatic and statistically significant decrease in DNTs, lymphadenopathy, splenomegaly, and autoantibodies after only 4 weeks when comparing rapamycin-treated mice with controls. Rapamycin induced apoptosis through the intrinsic mitochondrial pathway. We compared rapamycin to mycophenolate mofetil, a second-line agent used to treat ALPS, and found rapamycin's control of lymphoproliferation was superior. We conclude that rapamycin is an effective treatment for murine ALPS and should be explored as treatment for affected humans.

Basic immunosuppressive drugs outside solid organ transplantation

Immunosuppressive drugs are the backbone of solid organ transplantation. The introduction of new immunosuppressive drugs led to improved patient and organ survival rates. Nowadays, acute rejection can be reduced to a minimum. Individualization and avoidance of drug-related adverse effects became a new goal to achieve. The potency of immunosuppressive drugs makes them attractive for use in various autoimmune diseases; therefore, the experience on immunosuppressive drugs outside the field of organ transplantation is analysed in this review.

Effects of perioperative antiinflammatory and immunomodulating therapy on surgical wound healing

Patients with various rheumatologic and inflammatory disease states commonly require drugs known to decrease the inflammatory or autoimmune response for adequate control of their condition. Such drugs include nonsteroidal antiinflammatory drugs (NSAIDs), cyclooxygenase (COX)-2 inhibitors, corticosteroids, disease-modifying antirheumatic drugs (DMARDs), and biologic response modifiers. These drugs affect inflammation and local immune responses, which are necessary for proper wound healing in the perioperative setting, thereby potentially resulting in undesirable postoperative complications. Such complications include wound dehiscence, infection, and impaired collagen synthesis. The end result is delayed healing of soft tissue and bone wounds. The current literature provides insight into the effect of some of these drugs on wound healing. For certain drugs, such as methotrexate, trials have been conducted in humans and direct us on what to do during the perioperative period. Whereas with other drugs, we must rely on either small-animal studies or extrapolation of data from human studies that did not specifically look at wound healing. Unfortunately, no clear consensus exists on the need and optimum time for withholding therapy before surgery. Likewise, clinicians are often uncertain of the appropriate time to resume therapy after the procedure. For those drugs with limited or no data in this setting, the use of pharmacokinetic properties and biologic effects of each drug should be considered individually. In some cases, discontinuation of therapy may be required up to 4 weeks before surgery because of the long half-lives of the drugs. In doing so, patients may experience an exacerbation or worsening of disease. Clinicians must carefully evaluate individual patient risk factors, disease severity, and the pharmacokinetics of available therapies when weighing the risks and benefits of discontinuing therapy in the perioperative setting.

Baohuoside-1 inhibits activated T cell proliferation at G1–S phase transition

BACKGROUND

The effect of baohuoside-1 (B1), a novel flavonoid, on cell proliferation and the cell cycle was evaluated in this study.

METHODS

The antiproliferative properties of B1 were evaluated by proliferation assay. Western blotting and flow cytometric analysis were employed to investigate the expression of cyclins and cyclin-dependent kinase proteins.

RESULTS

The major findings were (1) B1 effectively inhibited the cell proliferation activated by mitogenic antigen, with a 50% inhibitory concentration in low muM and in a dose- and time-dependent manner. (2) B1 resulted in G(1)-S phase cells arrest. (3) It down-regulated the expression of cyclin A, D and p33 cyclin-dependent kinase-2 (p33cdk2) proteins. (4) B1 suppressed the growth of several tumor cell lines. (5) B1 prevented rat heart allograft rejection in vivo.

CONCLUSIONS

B1 immunosuppression of mitogen-activated T cell proliferation occurs in G(1)-S transition. It may be associated with the expression of cyclin A, D and p33cdk2 proteins. B1 prevents rat heart allograft rejection in vivo. The mechanism of B1 is different from tacrolimus and sirolimus.

Infliximab therapy in established rheumatoid arthritis: an observational study

PURPOSE

To investigate the efficacy, toxicity and drug discontinuation rate in an observational study of patients with established rheumatoid arthritis treated with infliximab.

SUBJECTS AND METHODS

Between September 1999 and June 2003, we enrolled 84 patients with rheumatoid arthritis who were being treated with infliximab. All patients met the American College of Rheumatology criteria for rheumatoid arthritis and had been refractory to (or did not tolerate) at least two disease-modifying antirheumatic drugs. Patients entering the study had a negative purified protein derivative skin test, were fully informed about the treatment regimen, and were followed up at predefined times according to a standardized protocol. Data concerning infliximab dosage, tolerability, adverse events, concomitant therapy, dosage interval, and drug discontinuation were all recorded. In addition, the clinical and laboratory variables according to the American College of Rheumatology 20% and 50% response criteria and the disease activity score for the 28 joint indices were also recorded.

RESULTS

There were 61 women and 23 men with a mean age of 59 +/- 8 years and mean disease duration of 11 +/- 6 years. Seventy-five percent (63/84) were seropositive for IgM rheumatoid factor. After the first year of treatment, 84.5% of patients continued to be treated with infliximab, whereas this percentage was 73% after the second year and 59% after the third year of treatment. The American College of Rheumatology 20% response criteria was met by 59/84 (70%) of patients, and 38/84 (45%) of the patients achieved the 50% response criteria in the first year of treatment. At the second year of therapy, the American College of Rheumatology 20% response criteria were reached by 35/84 (42%) of the patients and the 50% response criteria by 27/84 (32%). At the third year of treatment with infliximab, the American College of Rheumatology 20% and 50% response criteria were achieved by 13/84 (15.5%) and 10/84 (12%) of the patients, respectively. Twenty-eight of eighty-four (33%) patients discontinued infliximab therapy. The risk of drug discontinuation decreased with the concomitant use of methotrexate. The main reasons for drug discontinuation were adverse drug reactions (16/84, 19%), followed by lack of efficacy (9/84, 11%). The main reasons for drug discontinuation due to side effects were immediate hypersensitivity reactions (9/84, 11%) and infections (6/84, 7%).

CONCLUSION

Infliximab was found to be an alternative treatment with a relatively acceptable toxicity profile, despite the fact that two patients developed pulmonary tuberculosis. After the third year of therapy, 59% of patients continued to be treated with infliximab. The concomitant use of methotrexate was associated with the continuation of infliximab therapy.

Signal transduction pathways: new targets for treating rheumatoid arthritis

Biotherapies and other new treatments introduced over the last few years have considerably enriched the therapeutic armamentarium for rheumatoid arthritis. Nevertheless, primary refractoriness or secondary escape phenomenon may occur, indicating a need for identifying new treatment targets. Promising candidates can be found among compounds involved in signal transduction pathways, most notably protein kinases (mitogen-activated protein kinase, MAPK and phosphatidylinositol-3 protein kinase, PI3) and transcription factors (nuclear factor kappa B, NF-kappaB; activating protein 1, AP-1; CCAAT/enhancer-binding protein, C/EBP and signal transducer and activator of transcription, STAT). Inhibition of signal transduction pathways may be achievable via three main strategies: pharmacological inhibitors, anti-sense or more specific inhibitors such as oligionucleotides or interfering mRNA, and induced overexpression of naturally occurring inhibitors. Clinical trials are under way to evaluate pharmacological inhibitors such as p38 MAPK. Although the preliminary results are promising, proof of safety has not yet been obtained. Signal transduction pathways are involved in normal processes, whose inhibition might produce untoward effects.

Signal pathways underlying homocysteine-induced production of MCP-1 and IL-8 in cultured human whole blood

AIM

To elucidate the mechanisms underlying homocysteine (Hcy)-induced chemokine production.

METHODS

Human whole blood was pretreated with inhibitors of calmodulin (CaM), protein kinase C (PKC), protein tyrosine kinase (PTK), mitogen-activated protein kinase (MAPK), and NF-kappaB and activators of PPARgamma for 60 min followed by incubation with Hcy 100 micromol/L for 32 h. The levels of mitogen chemokine protein (MCP)-1 and interleukin-8 (IL-8) were determined by enzyme-linked immunosorbant assay (ELISA).

RESULTS

Inhibitors of PKC (calphostin C, 50-500 nmol/L and RO-31-8220, 10-100 nmol/L), CaM (W7, 28-280 micromol/L), ERK1/2 MAPK (PD 98059, 2-20 micromol/L), p38 MAPK (SB 203580, 0.6-6 micromol/L), JNK MAPK (curcumin, 2-10 micromol/L), and NF-kappaB (PDTC, 10-100 nmol/L) markedly reduced Hcy 100 micromol/L-induced production of MCP-1 and IL-8 in human cultured whole blood, but the inhibitors of PTK (genistein, 2.6-26 micromol/L and tyrphostin, 0.5-5 micromol/L) had no obvious effect on MCP-1 and IL-8 production. PPARgamma activators (ciglitazone 30 micromol/L and troglitazone 10 micromol/L) depressed the Hcy-induced MCP-1 production but not IL-8 production in the cultured whole blood.

CONCLUSION

Hcy-induced MCP-1 and IL-8 production is mediated by activated signaling pathways such as PKC, CaM, MAPK, and NF-kappaB. Our results not only provide clues for the signal transduction pathways mediating Hcy-induced chemokine production, but also offer a plausible explanation for a pathogenic role of hyperhomocysteinemia in these diseases.

Anti-TNFα therapy in rheumatoid arthritis and autoimmunity

The aim of the study was to evaluate a panel of autoantibodies in patients affected by rheumatoid arthritis (RA) treated with anti-TNFalpha blockers, and to consider a different autoantibody induction effect by infliximab and etanercept; and in addition to evaluate in these cases a relationship between antinuclear antibody (ANA) titre and both C-reactive protein (CRP) and Blys levels. Fifty-four patients (8 men, 46 women, mean age 51.4 years, mean duration of disease 13.6 years) affected by refractory RA were treated with anti-TNFalpha blockers for 12 consecutive months; 43 patients were given infliximab and 11 etanercept. At baseline and every 4 months a panel of autoantibodies consisting of rheumatoid factor, antinuclear, anti-double-stranded DNA, anti-ENA, anti-mitochondrial, anti-thyroid and anti-neutrophil cytoplasmic antibodies (ANCA) was tested. At the same time CRP level was measured. Blys level was determined at baseline and after 1 year in five cases that developed a strong positivity for ANA during infliximab therapy. In 41 cases (95.3%) treated with infliximab, ANA were detected on at least one occasion, and in almost half of these cases the titre was very high, equal to or higher than 1:1.280. On the other hand, patients treated with etanercept presented ANA positivity in a lower percentage of cases and at a low titre. No correlation was found between ANA titre and CRP level; Blys level did not present a constant trend in patients who developed a very high positivity for ANA. Anti-double-stranded DNA, anti-thyroid or ANCA were found only in a few patients, in the absence of a clinical picture indicative of systemic lupus erythematosus, autoimmune thyroiditis or ANCA-associated vasculitis. A different incidence of ANA positivity was found in infliximab- and etanercept-treated RA patients; this finding might be due to the partially different method of inhibition of TNFalpha between the two drugs. Both CRP and Blys do not seem to participate in this phenomenon. Other autoantibodies were detected in a few patients, but no case of onset of new autoimmune disorders was observed.

Mycophenolate mofetil in solid-organ transplantation

This review focuses on the use of mycophenolate mofetil (MMF) as an immunosuppressive agent in solid-organ transplantation. MMF, a non-competitive inhibitor of inosine monophosphate dehydrogenase, blocks de novo purine synthesis in T and B lymphocytes, resulting in the selective inhibition of proliferation of these cells in response to antigenic stimuli. MMF may also promote apoptosis of these cells. The immunosuppressive ability of MMF is thought to derive mainly from the inhibition of inosine monophosphate dehydrogenase. The other effects of MMF include suppression of antibody synthesis by B lymphocytes, inhibition of proliferation of smooth muscle cells in culture and impaired glycosylation of adhesion molecules. MMF may exhibit anti-inflammatory effects resulting from decreased activity of the inducible form of nitric oxide synthase, a consequence of depletion of tetrahydrobiopterin, which leads to decreased generation of peroxynitrite, a pro-inflammatory molecule. The pharmacokinetics, pharmacodynamics and principles underlying therapeutic drug monitoring of MMF are reviewed. The results of the pivotal clinical trials of MMF in kidney and heart transplantation are discussed and a summary of the major studies demonstrating a positive effect of MMF on renal transplantation outcomes is presented. The use of MMF in the context of ABO-incompatible renal transplantation, renal transplantation in highly sensitised and cross-match positive recipients, humoral rejection of renal allografts, chronic allograft nephropathy and steroid/calcineurin inhibitor minimisation in renal transplantation are also discussed.

Methotrexate intolerance in elderly patients with rheumatoid arthritis: what are the alternatives?

Rheumatoid arthritis (RA) in the elderly may be mild or severe, with features that are similar to those seen in younger patients. As such, the treatment regimen in the elderly is almost the same as in younger patients. Methotrexate is the most popular disease-modifying antirheumatic drug (DMARD) for the treatment of RA in the US and Europe. It has excellent efficacy and an acceptable toxicity profile. However, a number of patients do not tolerate methotrexate and an alternative DMARD should be chosen. In the elderly, choice of an alternative DMARD should be made after careful consideration of several age-related factors including concomitant diseases, existing medication, drug compliance, and altered age-related physiology and pharmacokinetics. In elderly patients with RA who are unable to tolerate methotrexate, the alternatives are hydroxychloroquine or sulfasalazine for mild-to-moderate disease and cyclosporin or leflunomide for severe disease, given in combination with low-dose oral corticosteroids. This is primarily due to their efficacy combined with a relatively low toxicity profile compared with other DMARDs, such as gold compounds, penicillamine, azathioprine and alkylating agents. Where the above DMARDs are contraindicated, anticytokine therapy should be considered. The therapy of RA is a dynamic process and requires a delicate balance of benefits and risks. Experience and familiarity with the currently available agents, and knowledge of the nature of the disease are necessary in order to make better therapeutic decisions.

Lattice stabilization and enhanced diffraction in human p38α crystals by protein engineering

Mitogen-activated protein (MAP) kinase p38 alpha is activated in response to environmental stress and cytokines, and plays a significant role in inflammatory responses. For these reasons, it is an important target for the treatment of a wide range of inflammatory and autoimmune diseases. The crystals of p38 alpha that we obtained by published procedures were usually small, quite mosaic, and difficult to reproduce and thus posed a difficulty for the intensive high-resolution studies required for a structure-guided drug discovery approach. Based on crystallographic and biochemical evidences, we prepared a single point mutation of a surface cysteine (C162S) and found that it prevents aggregation and improves the homogeneity and stability of the enzyme. This mutation also facilitates the crystallization process and increases the diffracting power of p38 alpha crystals. Surprisingly, we found that the mutation induces a change in the conformation of a nearby surface loop resulting in stronger lattice interactions, consistent with the improved crystal quality. The mutant protein, because of its improved stability and strengthened lattice interactions, thus provides a significantly improved reagent for use in structure-based drug design for this important disease target.

Effects of tacrolimus on ischemia-reperfusion injury

In addition to efficacious immunosuppression for the benefit of organ transplantation, tacrolimus has diverse actions that result in amelioration of ischemia-reperfusion injury. Knowledge is accumulating rapidly on the mechanisms through which tacrolimus exerts these cytoprotective effects, including alterations in microcirculation, free radical metabolism, calcium-activated pathways, inflammatory cascades, mitochondrial stability, apoptosis, stress-response proteins, and tissue recovery. Within the nucleus, actions mediating the effects of tacrolimus appear to be dominantly influenced by interactions with the transcription factor, nuclear factor-kappaB. Because tacrolimus is a cornerstone agent in immunosuppression regimens throughout the world and knowledge of its cellular mechanisms is evolving, it is important to update the clinical literature with this information. We reviewed the published literature with intent to portray the interactions of tacrolimus in the intricate cellular mechanisms initiated by ischemia and reperfusion.