Is steroid resistance related to multidrug resistance-I (MDR-I) in rheumatoid arthritis?

P-glycoprotein Activity Correlates With Treatment Response in 2 Leukemia Child Patients

Acute lymphoblastic leukemia is the most important childhood cancer. Multidrug resistance is an important factor of poor prognosis. We present the P-glycoprotein (P-gp) activity in 2 patients with different outcomes. Both patients had B-cell acute lymphoblastic leukemia; they were responding properly to the treatment, but one of them had an increment in the P-gp activity that correlates with an increment in the disease manifestation, the patient had to be hospitalized and developed sepsis and subsequently died. P-gp levels were correlated with disease progression. P-gp activity needs to be evaluated during treatment to assess and prevent disease relapse or the patient´s death.

Measurement and Clinical Significance of Biomarkers of Oxidative Stress in Humans

Oxidative stress is the result of the imbalance between reactive oxygen species (ROS) formation and enzymatic and nonenzymatic antioxidants. Biomarkers of oxidative stress are relevant in the evaluation of the disease status and of the health-enhancing effects of antioxidants. We aim to discuss the major methodological bias of methods used for the evaluation of oxidative stress in humans. There is a lack of consensus concerning the validation, standardization, and reproducibility of methods for the measurement of the following: (1) ROS in leukocytes and platelets by flow cytometry, (2) markers based on ROS-induced modifications of lipids, DNA, and proteins, (3) enzymatic players of redox status, and (4) total antioxidant capacity of human body fluids. It has been suggested that the bias of each method could be overcome by using indexes of oxidative stress that include more than one marker. However, the choice of the markers considered in the global index should be dictated by the aim of the study and its design, as well as by the clinical relevance in the selected subjects. In conclusion, the clinical significance of biomarkers of oxidative stress in humans must come from a critical analysis of the markers that should give an overall index of redox status in particular conditions.

Association of the ABCB1 C3435T polymorphism with responsiveness to and toxicity of DMARDs in rheumatoid arthritis : A meta-analysis

OBJECTIVE

The aim of this study was to investigate whether the C3435T polymorphism in the gene encoding multidrug resistance protein 1 (ABCB1) can predict responsiveness to or toxicity of disease-modifying antirheumatic drugs (DMARDs) in patients with rheumatoid arthritis (RA).

METHODS

We conducted a meta-analysis of studies on the association between the ABCB1 C3435T polymorphism and nonresponsiveness to or toxicity of DMARDs in RA patients, using the PUBMED and EMBASE electronic citation databases. Subsequent inclusion/exclusion procedures were performed and then data were extracted for association analysis.

RESULTS

A total of 14 comparison studies from 9 articles met our inclusion criteria. This final group comprised 4 studies containing data on associations between the ABCB1 C3435T polymorphism and RA susceptibility, 5 studies on the response to DMARDs, and 5 on toxicity of DMARDs in RA patients according to ABCB1 polymorphism status. Meta-analysis revealed no association between RA susceptibility and the ABCB1 C3435T polymorphism [odds ratio (OR) for the T allele = 0.948, 95 % confidence interval (CI) 0.756-1.189, p = 0.645]. Meta-analysis showed no association between the ABCB1 C3435T T allele and a nonresponse to DMARD therapy (OR 0.952, 95 % CI 0.516-1.685, p = 0.817). Stratification by DMARD type indicated no association between the ABCB1 C3435T T allele and nonresponse to methotrexate (MTX) treatment (OR 1.201, 95 % CI  0.456-3.164, p = 0.711). However, the analysis did indicate that MTX toxicity was associated with the ABCB1 C3435T polymorphism in RA under an overdominant model (TC vs. TT + CC; OR 0.483, 95 % CI 0.259-0.900, p = 0.022), evidencing a lower risk of MTX toxicity for heterozygotes (TC) than homozygotes (TT and CC).

CONCLUSION

This meta-analysis demonstrated that the ABCB1 C3435T polymorphism may be not associated with responsiveness to DMARD therapy, but may be associated with MTX toxicity in RA.

Interference of flavonoids with fluorescent intracellular probes: methodological implications in the evaluation of the oxidative burst by flow cytometry

The evaluation of oxidative burst is particularly relevant in many pathological and subclinical conditions. Flow cytometry provides quick and accurate measures of the reactive oxygen species production by leukocytes in most situations. However, spurious results, related to probes' efflux may be observed in several instances. Many factors affect the evaluation of the oxidative burst with fluorescent probes that require intracellular deacetylation and could be substrate of the multidrug resistance proteins (MDR). After discussing the implications of the efflux of fluorophores in the normalization strategies in flow cytometry assays, we have pointed out the possible interference of flavonoids with fluorescet probes' staining and signal. We have also reviewed the results from human intervention studies regarding the evaluation of oxidative burst with these probes. In vitro, at concentrations close to post-ingestion circulating levels, some flavonoids and their metabolites could interfere with probes' staining and fluorescence signal through different mechanisms, such as the inhibition of esterases, the modulation of the MDR-mediate efflux of probe and the inhibition of the oxidation of probe. These effects may explain the contrasting results obtained by human intervention studies. Finally, also inflammatory state or the use of drugs substrate of MDR proteins could affect the evaluation of the oxidative burst with intracellular probes.

Multidrug resistance protein-1 expression, function and polymorphisms in patients with rheumatoid arthritis not responding to methotrexate

OBJECTIVE

To study the expression, function and polymorphism of MDR-1 protein on the peripheral blood lymphocytes in patients with RA following treatment with MTX and its relationship with response to therapy.

METHODS

RA patients naïve to MTX/DMARD- and glucocorticoid were enrolled. Expression and function of MDR-1 was carried out by flow cytometry at baseline and after 4 months of therapy. MDR-1 expression was measured by relative fluorescence intensities and percentage of positive cells. MDR-1 function was assessed by Rhodamine efflux in presence or absence of verapamil. Patients with reduction in disease activity score 28 ≥1.2 were defined as responders and <1.2 as non-responders. Three single nucleotide polymorphisms in MDR-1 gene, 3435T, 1236T and 2677T/A were studied.

RESULTS

Fifty-two patients of RA were grouped into responders (n = 41), and non-responders (n = 11) as per the defined criteria. There was no difference between the groups in terms of age, sex ratio or duration of illness, MTX dose and follow-up duration. The expression and function of the MDR-1 protein reduced significantly in the responder group after the treatment with MTX when compared to the baseline evaluation. The decrease was significant when compared to the non-responders at the fourth month. MDR-1 expression and function either increased or remained the same in the non-responder group after treatment with MTX. MTX unresponsiveness was not related to any of the three polymorphisms studied.

CONCLUSION

Persistent expression and function of MDR-1 identifies a subset of RA patients not responding to MTX. Its early recognition may help in appropriately modulating therapy.

Pharmacogenetics and pharmacogenomics in rheumatology

Pharmacogenetics and pharmacogenomics deal with possible associations of a single genetic polymorphism or those of multiple gene profiles with responses to drugs. In rheumatology, genes and gene signatures may be associated with altered efficacy and/or safety of anti-inflammatory drugs, disease-modifying antirheumatic drugs (DMARDs) and biologics. In brief, genes of cytochrome P450, other enzymes involved in drug metabolism, transporters and some cytokines have been associated with responses to and toxicity of non-steroidal anti-inflammatory drugs, corticosteroids and DMARDs. The efficacy of biologics may be related to alterations in cytokine, chemokine and FcγR genes. Numerous studies reported multiple genetic signatures in association with responses to biologics; however, data are inconclusive. More, focused studies carried out in larger patient cohorts, using pre-selected genes, may be needed in order to determine the future of pharmacogenetics and pharmacogenomics as tools for personalized medicine in rheumatology.

Neuroimmunoendocrine interactions in patients with recurrent major depression, increased early life stress and long-standing posttraumatic stress disorder symptoms

BACKGROUND

Traumatic events experienced in childhood may lead to psychiatric diseases in adult life, including major depressive disorder (MDD). It remains obscure to what extent early life stress (ELS) is associated with biologically relevant changes in MDD.

OBJECTIVE

We investigated both neuroendocrine and immunological correlates in recurrent MDD with ELS and current posttraumatic stress disorder symptoms.

METHODS

Thirty-eight female MDD patients with or without childhood trauma and 15 healthy controls took part in this study. Salivary cortisol and dehydroepiandrosterone sulfate (DHEAS) were assessed by radioimmunoassays. Peripheral blood mononuclear cells (PBMCs) were isolated and T cell proliferation and cellular sensitivity to steroids and DHEAS were evaluated by colorimetric assays. Th1/Th2 cytokines were assessed by cytometric bead arrays.

RESULTS

MDD patients with or without previous trauma had similarly lower salivary cortisol and DHEAS in parallel with blunted T cell proliferation. PBMCs of depressives were significantly less sensitive to dexamethasone or epinephrine than those of the controls. PBMCs of MDD patients produced significantly lower interleukin (IL)-2, IL-4 and tumor necrosis factor-α levels when compared to healthy controls.

CONCLUSION

We found that a history of ELS did not modify the blunted neuroendocrine and immunological alterations presented by recurrent depressed patients.

MDR1a/1b gene silencing enhances drug sensitivity in rat fibroblast-like synoviocytes

BACKGROUND

Drug resistance mediated by P-glycoprotein (P-gp) is one of the major reasons for the failure of rheumatoid arthritis (RA) therapy with disease modifying anti-rheumatic drugs and glucocorticoids. In the present study, we aimed to investigate the in vitro effectiveness of small interfering RNA (siRNA) to render rat fibroblast-like synoviocytes (FLS) susceptible to drugs. We also attempted the electroporation-mediated transfer of siRNA against multidrug resistance (MDR) genes into rat knee joints.

METHODS

FLS were transfected with siRNAs corresponding to MDR1a and MDR1b genes. FLS were treated with dexamethasone (DEX) and lipopolysaccharide. The mRNA and protein levels of tumor necrosis factor-alpha, interleukin (IL)-6 and IL-1beta were measured. Both siRNAs were co-transduced into rat knee joints by an electroporation method and evaluated the target gene expressions in the synovium.

RESULTS

Each siRNA could sequence-specifically reduce the target gene expression by over 70% and effectively suppressed P-gp expression and function in the FLS. Both gene expression and protein production of the inflammatory cytokines in the cells transfected with siRNA were reduced by a greater amount compared to in control cells. The in vivo electroporation-mediated transduction of siRNA could significantly inhibit the target gene expressions.

CONCLUSIONS

MDR1a/1b gene silencing by siRNA could effectively inhibit P-gp in rat FLS, resulting in a significant enhancement of the anti-inflammatory effects of DEX. The in vivo siRNA transduction could successfully silence MDR gene expression in the rat synovium. These findings indicate that the siRNA targeting MDR gene could be a useful tool for treating refractory arthritis in RA.

Neuroendocrine-immune interactions in rheumatoid arthritis: mechanisms of glucocorticoid resistance

Rheumatoid arthritis (RA) is characterized by chronic inflammation of the synovial membrane, leading to joint destruction. Many autoimmune diseases and disease states of chronic inflammation are accompanied by alterations in the complex interactions between the endocrine, nervous and immune systems. Glucocorticoids, an end product of the hypothalamic-pituitary-adrenal axis, are a mainstay treatment for many autoimmune diseases, including RA, because of their potent anti-inflammatory action. However, about 30% of patients with RA fail to respond to steroid therapy. There are various mechanisms that may contribute to the development of glucocorticoid resistance in inflammatory disorders, which will be the subject of this review. In addition, glucocorticoid resistance may be a contributing factor in the development of inflammatory/autoimmune diseases themselves. Therefore, further elucidation of these mechanisms will reveal new targets for therapeutic intervention in the treatment of RA.

Relaxation and guided imagery program in patients with breast cancer undergoing radiotherapy is not associated with neuroimmunomodulatory effects

OBJECTIVE

Treatment of breast cancer is usually associated with significant psychological stress. In this study, we examined the effects of relaxation and visualization therapy (RVT) on psychological distress, cortisol levels, and immunological parameters of breast cancer patients undergoing radiotherapy.

METHODS

Participants were randomly assigned to either the experimental (n=20) who underwent group RVT for 24 consecutive days or control group (n=14) who were on radiotherapy only. Psychological scores (stress, anxiety, and depression) were measured by structured clinical interviews. Salivary cortisol was assessed along the day. Lymphocytes were isolated and cultured to measure T-cell proliferation and sensitivity to glucocorticoids (GCs).

RESULTS

RVT was effective to reduce stress, anxiety, and depression scores (all P<.05). However, cortisol levels as well as proliferation remained unchanged following RVT. Although T cells of experimental group were more sensitive to GCs than cells of controls at baseline, no changes were noted following RVT. Cortisol levels were positively correlated to anxiety and depression scores and inversely correlated to T-cell proliferation and sensitivity to GCs.

CONCLUSION

We conclude that the psychological intervention was capable to attenuate the emotional distress presented during radiotherapy treatment. A longer RVT or worse psychological morbidity at baseline may be necessary to translate psychological into biological changes.