Treatment strategy based on targeting P-glycoprotein on peripheral lymphocytes in patients with systemic autoimmune disease

Study of pathogenic T-helper cell subsets in Asian Indian patients with Takayasu arteritis

The relapses and refractory disease are a challenge in the management of patients with Takayasu arteritis (TAK). We quantified pathogenic CD4 + memory T helper cells bearing surface markers CD161 and/or p-glycoprotein (MDR1) in patients with TAK. Peripheral blood mononuclear cells of 21 patients with TAK and 16 age-matched controls were stained with anti-CD3, anti-CD4, anti-CD45RA, anti-CD161 and anti-p-glycoprotein antibodies and subjected to flow cytometry by FACS ARIAIII. Eighteen patients underwent follow-up immunophenotyping. Intracellular staining for interleukin-17 and interferon-γ was performed for 18 patients and 11 controls. Surgical arterial biopsies of 6 TAK and 5 non-inflammatory controls were subjected to immunohistochemistry with anti-CD161 and anti-p-glycoprotein. At baseline the frequency of MDR1 + CD4 + and CD161 + MDR1 + CD4 + memory T cells was higher in TAK than controls (p = 0.002 and 0.01, respectively). After stimulation, the frequency of IFN-y + CD161 + cells was higher in TAK than controls (p = 0.028). Modal fluorescence intensity of CD161 + MDR1 + CD45RA - CD4 + cells was higher in active as compared with stable disease (p = 0.041). At 6 months, MDR1 + and CD161 + MDR1 + memory CD4 + T cells decreased significantly only in patients who had complete/partial response to treatment (p = 0.047 and 0.02, respectively). To conclude, MDR1 + and MDR1 + CD161 + CD4 + memory T-helper cells are increased in patients with TAK. These cells decreased only in patients with response to treatment during subsequent follow-up.

Multitarget therapy with a corticosteroid, cyclosporine and mycophenolate mofetil for idiopathic membranous nephropathy: a prospective randomized controlled trial

BACKGROUND

The effectiveness of multitarget combination therapy with a corticosteroid, cyclosporine and mycophenolate mofetil for idiopathic membranous nephropathy (IMN) is unclear. In the present study, we aimed to compare the efficacy and safety of multitarget therapy with a cyclical corticosteroid-cyclophosphamide regimen in patients with IMN.

METHODS

This was a single-centre, prospective, randomized, controlled trial. We randomly assigned patients with IMN to receive multitarget therapy (a combination of prednisone, cyclosporine and mycophenolate mofetil) or 6-month cyclical treatment with a corticosteroid and cyclophosphamide. The study patients were followed up for 12 months. The primary outcome was a composite of complete or partial remissions at 12 months. Adverse events were also assessed.

RESULTS

The study cohort comprised 78 patients, 39 of whom received multitarget therapy and the other 39 cyclical alternating treatment with a corticosteroid and cyclophosphamide. At 12 months, 31 of 39 patients (79%) in the multitarget therapy group and 34 of 39 (87%) in the corticosteroid-cyclophosphamide group had achieved complete or partial remissions (relative risk 0.93; 95% confidence interval 0.72-1.21; P = .85; log-rank test). The prevalence of adverse events was significantly lower in the multitarget therapy group than in the corticosteroid-cyclophosphamide group [46% (18 of 39) vs 74% (29 of 39); P < .05].

CONCLUSIONS

Multitarget therapy for IMN patients is noninferior to cyclical alternating treatment with corticosteroid and cyclophosphamide in inducing proteinuria remission and has a better safety profile than the corticosteroid-cyclophosphamide combination.

Steroid Resistance Associated with High MIF and P-gp Serum Levels in SLE Patients

Approximately 30% of patients with systemic lupus erythematosus (SLE) present steroid resistance (SR). Macrophage migration inhibition factor (MIF) and P-glycoprotein (P-gp) could be related to SR. This work aims to evaluate the relationship between MIF and P-pg serum levels in SR in SLE. Methods: Case−control study including 188 SLE patients who were divided into two groups (90 in the steroid-resistant group and 98 in the steroid-sensitive (SS) group) and 35 healthy controls. MIF and P-gp serum levels were determined by ELISA. Multivariable logistic regression and chi-squared automatic interaction detection (CHAID) were used to explore risk factors for SR. Results: The steroid-resistant group presented higher MIF and P-gp serum levels in comparison with the SS (p < 0.001) and reference (p < 0.001) groups. MIF correlated positively with P-gp (rho = 0.41, p < 0.001). MIF (≥15.75 ng/mL) and P-gp (≥15.22 ng/mL) were a risk factor for SR (OR = 2.29, OR = 5.27). CHAID identified high P-gp as the main risk factor for SR and high MIF as the second risk factor in those patients with low P-gp. Conclusions: An association between MIF and P-gp serum levels was observed in SR. CHAID identified P-gp ≥ 15.22 ng/mL as the main risk factor for SR. More studies are needed to validate these results.

Mechanism of Action and Efficacy of Immunosupressors in Lupus Nephritis

Approximately 70% of the patients with systemic lupus erythematosus will have clinical evidence of kidney damage during their evolution. Patients with impaired renal function at onset and those with recurrent flares have a poor prognosis. Understanding the mechanism of action of immunosuppressants is essential for proper prescription. Steroids inhibit the DNA sequence that promotes the release of inflammatory cytokines. Phosphoramide mustard, metabolite of cyclophosphamide, cross-link with the DNA, causing the aggregation of an alkyl group, causing cell death. Mycophenolate inhibits inosine monophosphate dehydrogenase, prevents de novo synthesis of guanine, inducing cell arrest in S phase. Azathioprine blocks the synthesis of purines and induces apoptosis. Calcineurin inhibitors prevent the dephosphorylation of NFAT and reduce the production of interleukin 2. Antimalarials alter the enzymatic release of lysosomes by increasing intravesicular pH. The mechanism of action of rituximab is related to complement-dependent cytotoxicity and the elimination of anti-CD20-labeled B cells. Progress in the knowledge and management of low doses of steroids may change the current paradigm and reduce the frequency of related adverse events. Mycophenolate seems to be a better choice than cyclophosphamide for induction, it is also preferred over azathioprine as a maintenance immunosuppressive agent, although azathioprine is preferred in women with a desire for conception, those pregnant, or with low resources. For treatment-resistant cases, tacrolimus, rituximab or belimumab may be effective. Ongoing clinical trials with new drugs offer promising results.

Towards next-generation personalization of tacrolimus treatment: a review on advanced diagnostic and therapeutic approaches

The benefit of personalized medicine is that it allows the customization of drug therapy - maximizing efficacy while avoiding side effects. Genetic polymorphisms are one of the major contributors to interindividual variability. Currently, the only gold standard for applying personalized medicine is dose titration. Because of technological advancements, converting genotypic data into an optimum dose has become easier than in earlier years. However, for many medications, determining a personalized dose may be difficult, leading to a trial-and-error method. On the other hand, the technologically oriented pharmaceutical industry has a plethora of smart drug delivery methods that are underutilized in customized medicine. This article elaborates the genetic polymorphisms of tacrolimus as case study, and extensively covers the diagnostic and therapeutic technologies which aid in the delivery of personalized tacrolimus treatment for better clinical outcomes, thereby providing a new strategy for implementing personalized medicine.

Tetrandrine enhances glucocorticoid receptor translocation possibly via inhibition of P-glycoprotein in daunorubicin-resistant human T lymphoblastoid leukemia cells

Glucocorticoids are used as anticancer and immunosuppressive agents, whereas glucocorticoid resistance has been observed in a significant fraction of patients due to overexpression of P-glycoprotein encoded by multi-drug resistance-1 gene. Tetrandrine is a bisbenzylisoquinoline alkaloid isolated from traditional herb Fangji. According to our previous report, tetrandrine potentiated glucocorticoid pharmacodynamics partially via inhibiting P-glycoprotein function. In the present study, we investigated whether glucocorticoid receptor translocation was influenced indirectly by tetrandrine via P-glycoprotein inhibition, using human T lymphoblastoid leukemia MOLT-4 cell line with little P-glycoprotein expression and its multidrug resistant sub-line MOLT-4/DNR exhibiting a large amount of P-glycoprotein. Molecular mechanism investigation suggested that overexpressed P-glycoprotein weakened the glucocorticoid receptor translocation in MOLT-4/DNR cells comparing with the parent MOLT-4 cells. Our data also suggested that tetrandrine enhanced nuclear glucocorticoid receptor translocation in MOLT-4/DNR cells indirectly by dual influences on P-glycoprotein, inhibiting the efflux function and downregulating the protein expression. Therefore, tetrandrine potentiated the cytotoxic effect of methylprednisolone against MOLT-4/DNR cells with less effects on MOLT-4 cells. These effects of tetrandrine were suggested to be beneficial for the treatment of glucocorticoid resistant diseases induced by the overexpression of P-glycoprotein.

Role of P-glycoprotein on CD69+CD4+ cells in the pathogenesis of proliferative lupus nephritis and non-responsiveness to immunosuppressive therapy

Introduction

P-glycoprotein (P-gp) expression on activated lymphocytes in systemic lupus erythematosus (SLE) plays a role in active efflux of intracellular drugs, resulting in drug resistance. The role of P-gp-expressing lymphocytes in the pathogenesis of SLE remains unclear. The aim of this study was to determine the importance of P-gp⁺CD4⁺ cells in organ manifestations in refractory SLE.

Methods

The proportion of P-gp⁺CD4⁺ cells was determined by flow cytometry in peripheral blood of patients with SLE (n=116) and healthy adults (n=10). Renal biopsy specimens were examined by immunohistochemistry for P-gp expression.

Results

CD69 is a marker of CD4 cell activation. The proportion of both P-gp-expressing CD4⁺ cells and CD69-expressing CD4⁺ cells in peripheral blood was higher in SLE than control. The proportion of P-gp⁺CD69⁺CD4⁺ cells correlated with Systemic Lupus Erythematosus Disease Activity Index and was higher in poor responders to corticosteroids. Furthermore, the proportion of P-gp⁺CD69⁺CD4⁺ cells was significantly higher in proliferative lupus nephritis (LN) with poor response to corticosteroids. The efficacy of immunosuppressive therapy depended on the regulation of the proportion of P-gp⁺CD69⁺CD4⁺ cells. Marked accumulation of P-gp⁺CD4⁺ cells in renal interstitial tissue and high proportion of peripheral P-gp⁺CD69⁺CD4⁺ cells were noted in patients with proliferative LN.

Conclusions

The results showed high proportion of P-gp⁺CD69⁺CD4⁺ cells in peripheral blood and their accumulation in renal tissue in patients with proliferative LN refractory to CS therapy, suggesting that P-gp expression on activated CD4⁺ T cells is a potentially useful marker for refractoriness to treatment and a novel target for treatment.

Calcineurin inhibitors in systemic lupus erythematosus

The calcineurin inhibitors (CNIs) belong to a group of immunosuppressive agents that block T-cell activation through the suppression of the calcium/calcimodulin-dependent phosphatase calcineurin. Agents such as cyclosporine A (CSA) and tacrolimus (TAC) have long been used in patients with systemic lupus erythematosus (SLE). TAC is preferred to CSA in SLE because of the lower frequency of cosmetic, hypertensive and dyslipidemic adverse effects. Recent randomised controlled trials have demonstrated noninferiority of TAC to mycophenolate mofetil (MMF) or cyclophosphamide (CYC) for induction therapy of lupus nephritis. Low-dose combination of TAC and MMF has also been shown to outperform CYC pulses in inducing remission of lupus nephritis in Chinese patients. TAC does not affect fertility and is relatively safe in pregnancy. In SLE patients who are intolerant or refractory to conventional immunosuppressives, or where contraindications to other immunosuppressive agents exist, TAC is an alternative option. However, the therapeutic window of TAC is narrow, and drug level monitoring is required to ensure drug exposure and minimise toxicities. Current evidence of TAC in lupus nephritis is limited to 6 months, and its long-term safety as maintenance therapy of SLE is yet to be determined. Newer chemical analogues of CNIs, such as voclosporin, with less variable plasma concentration are being tested in lupus nephritis.

Relevance of P-glycoprotein on CXCR4+ B cells to organ manifestation in highly active rheumatoid arthritis

INTRODUCTION

In rheumatoid arthritis (RA), P-glycoprotein (P-gp) expression on activated B cells is associated with active efflux of intracellular drugs, resulting in drug resistance. CXCR4 is associated with migration of B cells. This study was designed to elucidate the relevance of P-gp expression on CXCR4⁺ B cells to clinical manifestations in refractory RA.

METHODS

CD19⁺ B cells were analyzed using flow cytometry and immunohistochemistry.

RESULTS

P-gp was highly expressed especially on CXCR4⁺CD19⁺ B cells in RA. The proportion of P-gp-expressing CXCR4⁺ B cells correlated with disease activity, estimated by Simplified Disease Activity Index (SDAI), and showed marked expansion in RA patients with high SDAI and extra-articular involvement. In highly active RA, massive infiltration of P-gp⁺CXCR4⁺CD19⁺ B cells was noted in CXCL12-expressing inflammatory lesions of RA synovitis and RA-associated interstitial pneumonitis. In RA patient with active extra-articular involvement, intracellular dexamethasone level (IDL) in lymphocytes diminished with expansion of P-gp⁺CXCR4⁺ CD19⁺ B cells. Adalimumab reduced P-gp⁺CXCR4⁺ CD19⁺ B cells, increased IDL in lymphocytes, and improved the clinical manifestation and allowed tapering of concomitant medications.

CONCLUSIONS

Expansion of P-gp⁺CXCR4⁺ B cells seems to be associated with drug resistance, disease activity and progressive destructive arthritis with extra-articular involvement in RA.

Treatment of pediatric-onset lupus nephritis: a proposal of optimal therapy

Lupus nephritis (LN) is one of the major clinical manifestations of systemic lupus erythematosus (SLE) which occurs frequently in the early stages of pediatric-onset cases. Since SLE is a chronic disease associated with frequent disease flares and effective and safe maintenance therapy is required for achieving a favorable outcome, optimal treatment for LN in pubertal patients is a great challenge that remains to be overcome. Although its etiology remains unclear, it has been reported that the innate and adaptive immune systems have been reported to play an important role in the pathogenesis of SLE. However, studies of drugs that have been useful in controlling inflammatory pathways mediated by the innate and adaptive immune systems are now underway. In clinical practice, recent advances in the management of LN, together with earlier renal biopsy and selective use of aggressive immunosuppressive therapy, have contributed to a favorable outcome in children and adolescents with LN. However, the balance of the efficacy of treatment in terms of long-term prognosis and its adverse effects should be weighed in determining the treatment strategy.

Serum levels of P-glycoprotein and persistence of disease activity despite treatment in patients with systemic lupus erythematosus

Around 25% of patients with systemic lupus erythematosus (SLE) could be refractory to conventional therapies. P-glycoprotein expression on cell surface has been implied on drug resistance, however, to date, it is unknown if P-gp serum levels are associated with SLE disease activity. Evaluate the association of serum P-gp levels and SLE with disease activity despite treatment. A cross-sectional study was conducted on 93 female SLE patients, all receiving glucocorticoids at stable doses for the previous 6 months before to baseline. SLE patients were classified into two groups: (a) patients with active disease [SLE disease activity index (SLEDAI) ≥ 3] despite treatment, and (b) patients with inactive disease (SLEDAI < 3) after treatment. Forty-three healthy females comprised the control group. Serum P-gp, anti-DNA, and both anti-nucleosome antibody levels were measured using ELISA. Active-SLE patients despite treatment had higher P-gp levels compared with inactive-SLE after treatment (78.02 ng/mL ± 114.11 vs. 33.75 ng/mL ± 41.11; p = 0.018) or versus reference group subjects (30.56 ng/mL ± 28.92; p = 0.011). P-gp levels correlated with the scores of SLEDAI (r = 0.26; p = 0.01), Mexican-SLEDAI (MEX-SLEDAI) (r = 0.32; p = 0.002), SLICC/ACR damage index (r = 0.47; p < 0.001), and with prednisone doses (r = 0.33; p = 0.001). In the multivariate model, the high P-gp levels were associated with SLICC/ACR score (p = 0.001), and SLEDAI score (p = 0.014). Our findings support a relationship between serum P-gp levels and SLE with disease activity despite treatment, but it requires further validation in longitudinal studies.

Efficacy of Intravenous Cyclophosphamide Pulse Therapy for P-Glycoprotein-expressing B Cell-associated Active True Renal Lupus Vasculitis in Lupus Nephritis

True renal lupus vasculitis (TRLV), a vascular lesion usually associated with proliferative lupus nephritis (LN), is resistant to conventional treatments. The expression of P-glycoprotein (P-gp) on activated lymphocytes causes drug resistance. We herein report a patient with TRLV, minimal change LN, overexpression of P-gp on peripheral B cells, and accumulation of P-gp⁺ B cells at the site of TRLV. High-dose corticosteroids combined with intravenous cyclophosphamide pulse therapy resulted in clinical remission and the long-term normal renal function.

Pro: The use of calcineurin inhibitors in the treatment of lupus nephritis

Renal disease in systemic lupus erythematosus (SLE) carries significant morbidity and mortality. Cyclophosphamide (CYC)- and mycophenolate mofetil (MMF)-based induction regimens are not ideal in terms of efficacy and toxicity. The adverse effects of CYC, such as infection risk, infertility, urotoxicity and oncogenicity, limit its use in lupus nephritis. Although MMF is non-inferior to CYC as induction therapy and has reduced gonadal toxicity and oncogenic potential, meta-analyses of clinical trials do not show a lower rate of infective and gastrointestinal complications. Tacrolimus (TAC) has recently been shown to have equal efficacy to either MMF or CYC for inducing remission of lupus nephritis. A low-dose combination of MMF and TAC appears to be more effective than intravenous CYC pulses in Chinese patients, and has potential to replace the more toxic CYC regimens in high-risk subgroups. TAC may be considered as another non-CYC alternative for induction therapy of lupus nephritis and in those with refractory disease or intolerance to CYC or MMF. TAC has no negative effect on fertility in younger women, and unlike MMF and CYC, it is safe in pregnancy. However, TAC has a narrow therapeutic window and drug level monitoring is required to ensure drug exposure and minimize acute toxicities. Current evidence for the efficacy of TAC in lupus nephritis is limited to 6 months and the incidence of renal flare after discontinuation of therapy or switching to azathioprine appears to be higher than other induction agents. Long-term data and the incidence of chronic nephrotoxicity of TAC as maintenance therapy in lupus nephritis are currently lacking and further prospective trials are needed to address these issues.

Cell cycle kinetics, apoptosis rates and gene expressions of MDR-1, TP53, BCL-2 and BAX in transmissible venereal tumour cells and their association with therapy response

Transmissible venereal tumour (TVT) generally presents different degrees of aggressiveness, which makes them unresponsive to conventional treatment protocols. This implies a progressive alteration of their biological profile. This study aimed to evaluate the cytotoxicity, cell survival, apoptosis and cell cycle alterations in TVT cell cultures subjected to treatment with vincristine. Similarly, it assessed possible implications of MDR-1, TP53, BCL-2, and BAX gene expressions in eight TVT primary cultures for both resistance to chemotherapy and biological behaviour. When comparing TVT cells receiving vincristine to those untreated, a statistical difference related to increased cytotoxicity and decreased survival rates, and alterations in G1 and S cell cycle phases were found but without detectable differences in apoptosis. Increased MDR-1 gene expression was observed after treatment. The groups did not differ statistically in relation to the TP53, BAX and BCL-2 genes. Although preliminary, the findings suggest that such augmented expression is related to tumour malignancy and chemotherapy resistance.

P-glycoprotein in autoimmune rheumatic diseases

P-glycoprotein (Pgp) is a transmembrane protein of 170 kD encoded by the multidrug resistance 1 (MDR-1) gene, localized on chromosome 7. More than 50 polymorphisms of the MDR-1 gene have been described; a subset of these has been shown to play a pathophysiological role in the development of inflammatory bowel disease, femoral head osteonecrosis induced by steroids, lung cancer and renal epithelial tumors. Polymorphisms that have a protective effect on the development of conditions such as Parkinson disease have also been identified. P-glycoprotein belongs to the adenosine triphosphate binding cassette transporter superfamily and its structure comprises a chain of approximately 1280 aminoacid residues with an N-C terminal structure, arranged as 2 homologous halves, each of which has 6 transmembrane segments, with a total of 12 segments with 2 cytoplasmic nucleotide binding domains. Many cytokines like interleukin 2 and tumor necrosis factor alpha increase Pgp expression and activity. Pgp functions as an efflux pump for a variety of toxins in order to protect particular organs and tissues as the central nervous system. Pgp transports a variety of substrates including glucocorticoids while other drugs such as tacrolimus and cyclosporine A act as modulators of this protein. The most widely used method to measure Pgp activity is flow cytometry using naturally fluorescent substrates such as anthracyclines or rhodamine 123. The study of drug resistance and its association to Pgp began with the study of resistance to chemotherapy in the treatment of cancer and antiretroviral therapy for human immunodeficiency virus; however, the role of Pgp in the treatment of systemic lupus erythematosus, rheumatoid arthritis and psoriatic arthritis has been a focus of study lately and has emerged as an important mechanism by which treatment failure occurs. The present review analyzes the role of Pgp in these autoimmune diseases.

Efficacy of mizoribine-tacrolimus-based induction therapy for pediatric lupus nephritis

BACKGROUND

Recent advances in the management of lupus nephritis (LN) have also contributed to a favorable outcome in patients with pediatric-onset LN. Nevertheless, we believe that a more effective and less toxic treatment is needed to attain optimal control of pediatric-onset LN.

METHODS

Seven consecutive children with biopsy-proven LN (four with class III/IV and three with class V) received multitarget induction therapy consisting of mizoribine (MZR), tacrolimus (Tac), and prednisolone (PDN). They were prospectively evaluated at three, six, and 12 months, and at the latest observation point after a mean period of 32 months. Post-treatment renal biopsy was performed in two patients with class III/IV.

RESULTS

Despite gradually tapering the dose of concomitantly administered PDN, a significant improvement compared with baseline values was observed in the urinary, serological, and clinical assessment measures even at three months of treatment, and the favorable changes persisted throughout the treatment period in most of the study participants except for one. In two patients who underwent post-treatment renal biopsy, a marked histologic improvement was confirmed. No serious adverse events were observed.

CONCLUSIONS

Multitarget therapy may be an attractive option for the treatment of pediatric-onset LN. Further studies involving a larger number of patients are needed.

Long-term tacrolimus-based immunosuppressive treatment for young patients with lupus nephritis: a prospective study in daily clinical practice

BACKGROUND

The optimal long-term treatment for lupus nephritis (LN) in pubertal patients remains to be determined. Tacrolimus (Tac) inhibits T cell activation, and is therefore expected to be effective in patients with LN. However, little has been published about the long-term efficacy and safety of Tac-based immunosuppressive treatment of young patients with LN in daily clinical practice.

METHODS

Nineteen consecutive patients with biopsy-proven LN were recruited for an open-label, prospective, long-term Tac-based treatment regimen. Tac was administered once daily at a dose of 3 mg as induction- or reinduction-maintenance treatment. Four patients (21%) with new-onset LN received mizoribine at a dose of 150 mg once daily in addition to Tac. Treatment outcomes were defined by the European Consensus Lupus Activity Measurement (ECLAM) index, urinary protein/creatinine ratio (Up/cr), serum creatinine and serological lupus markers (complement C3, complement hemolytic activity, CH50, and anti-dsDNA antibody titer). Data on these parameters were collected prospectively. The median follow-up was 42 months.

RESULTS

Baseline characteristics of the patients were as follows: mean age, 18 years; Up/cr, 0.89 ± 1.17; serum C3, 68.1 ± 23.2 mg/dl (normal, 79-152 mg/dl); serum CH50, 26.4 ± 10.5 U/ml (normal, 23-46 U/ml); serum anti-dsDNA antibody titer, 69.3 ± 67.5 IU/ml (normal, <12.0 IU/ml); serum creatinine, 0.55 ± 0.18 mg/dl, and ECLAM index, 4.6 ± 1.9. Despite gradually tapering the dose of concomitantly administered prednisolone, a marked improvement compared with baseline values was observed in all outcome measures as early as 3 months after the initiation of treatment, and the favorable changes persisted throughout the treatment period in most of the patients. Sustained improvements in the outcome measures compared with the baseline values were confirmed after a mean of 42 months of treatment: ECLAM index, 1.1 ± 1.1; serum CH50, 36.0 ± 12.8 U/ml, anti-dsDNA antibody titer, 22.5 ± 26.5 IU/ml (all p < 0.01); Up/cr ratio, 0.35 ± 0.58, and serum C3 level, 79.7 ± 17.6 mg/dl (both p < 0.05). Serum creatinine level remained within the normal range in all the study participants. Complete response was achieved in 12 patients (63%), and a partial response was achieved in 5 patients (26%). The remaining 2 patients showed no response. No serious adverse effects were observed.

CONCLUSION

The data suggest that long-term, relatively low-dose Tac-based immunosuppressive treatment is beneficial and has low cytotoxicity, and therefore represents an attractive option for the treatment of young patients with LN in daily clinical practice. Further studies involving a larger number of patients are needed to confirm these results.

Treatment of young patients with lupus nephritis using calcineurin inhibitors

Recent advances in the management of lupus nephritis, together with earlier renal biopsy and selective use of aggressive immunosuppressive therapy, have contributed to a favorable outcome in children and adolescents with systemic lupus erythematosus (SLE). Nevertheless, we believe that a more effective and less toxic treatment is needed to attain an optimal control of the activity of lupus nephritis. Recent published papers and our experiences regarding treatment of young patients with lupus nephritis using calcineurin inhibitors are reviewed. Although it has been reported that intermittent monthly pulses of intravenous cyclophosphamide (IVCY) are effective for preserving renal function in adult patients, CPA is a potent immunosuppressive agent that induces severe toxicity, including myelo- and gonadal toxicity, and increases the risk of secondary malignancy. Thus, treatment for controlling lupus nephritis activity, especially in children and adolescents, remains challenging. Cyclosporine A (CsA) and tacrolimus (Tac) are T-cell-specific calcineurin inhibitors that prevent the activation of helper T cells, thereby inhibiting the transcription of the early activation genes of interleukin (IL)-2 and suppressing T cell-induced activation of tumor necrosis factor-α, IL-1β and IL-6. Therefore, both drugs, which we believe may be less cytotoxic, are attractive therapeutic options for young patients with lupus nephritis. Recently, a multidrug regimen of prednisolone (PDN), Tac, and mycophenolate mofetile (MMF) has been found effective and relatively safe in adult lupus nephritis. Since the mechanisms of action of MMF and Tac are probably complementary, multidrug therapy for lupus nephritis may be useful. We propose as an alternative to IVCY, a multidrug therapy with mizoribine, which acts very similarly to MMF, and Tac, which has a different mode of action, combined with PDN for pediatric-onset lupus nephritis. We also believe that a multidrug therapy including CsA and Tac may be an attractive option for young patients with SLE and lupus nephritis.

Immunological response as a source to variability in drug metabolism and transport

Through the last decades it has become increasingly evident that disease-states involving cytokines affect the pharmacokinetics of drugs through regulation of expression and activity of drug metabolizing enzymes, and more recently also drug transporters. The clinical implication is however difficult to predict, since these effects are dependent on the degree of inflammation and may be changed when the diseases are treated. This article will give an overview of the present understanding of the effects of cytokines on cytochrome P450 enzymes and drug transporters, and highlight the importance of considering these issues in regard to increasing use of the relatively new class of drugs, namely therapeutic proteins.