The p53 status in juvenile chronic arthritis and rheumatoid arthritis

Drug-resistance in rheumatoid arthritis: the role of p53 gene mutations, ABC family transporters and personal factors

Rheumatoid arthritis (RA) is an autoimmune disease that is associated with chronic inflammation in joints, which contribute to synovial membrane hyperplasia and cartilage damage. Conventional disease-modifying antirheumatic drugs (DMARDs), such as methotrexate (MTX) and leflunomide (LEF), are the common RA therapy to reduce inflammation and disease progression. Recently, drug-resistance in RA with conventional treatment has become an issue. Mutations in p53 tumor suppressor gene and overexpression of ABCB1/MDR-1/P-gp transporters may contribute to antirheumatic drug-resistance in RA. Biologic DMARDs (bDMARDs) are often prescribed, when conventional DMARDs fail to treat RA, by targeting proinflammatory mediators such as tumor necrosis factor-α (TNF-α) and interleukin (IL)-6. The efficacy of bDMARDs is affected by personal factors, for example, age, smoking, body mass index (BMI), immunogenicity, and genetic polymorphisms. This review highlights the role of p53 gene mutations, ABC family transporters and personal factors in antirheumatic drug-resistance, which may lead to new personalized therapies against RA with an increased drug-sensitivity.

Polymorphism of genes and implantation failure

Implantation failure is the most frequent cause of pregnancy loss in couples who try to conceive, either in a natural way or using assisted reproductive techniques (ART). Identify the precise mechanisms of implantation failure can lead to identify couples at risk and also providing appropriate therapeutic options to affected couples. Despite the high prevalence of this disorder, a few causing factors are demonstrated so far. Recent studies indicate that genetic factors play an important role in the occurrence of recurrent implantation failure. Although some of these factors, such as numerical chromosomal aneuploidy are known to be causative factors, there are some other factors that solely increase susceptibility to this event. In the present review we try to list the genetic polymorphisms that are known as susceptibility factors in implantation failure.

Associations between the p53 codon 72 polymorphisms and susceptibility to systemic lupus erythematosus and rheumatoid arthritis: a meta-analysis

Objective: The aim of this study was to determine whether the p53 codon 72 polymorphism confers susceptibility to systemic lupus erythematous (SLE) and rheumatoid arthritis (RA). Methods: A meta-analysis was conducted on the associations between the p53 codon 72 polymorphism and SLE or RA using: 1) allele contrast; 2) the recessive model; 3) the dominant model; and 4) the additive model. Results: A total of 10 studies, that is, 6 SLE and 4 RA studies, involving 1578 patients and 3138 controls were considered in the meta-analysis. Meta-analysis of the p53 codon 72 polymorphism showed no association between patients and the C allele (odds ratio (OR) = 0.834, 95% confidence interval (CI) = 0.599-1.161, p = 0.282), or between SLE and the p53 C allele (OR = 0.998, 95% CI = 0.765-1.302, p = 0.989). However, stratification by ethnicity showed an association between the p53 C allele and SLE in Asians (OR = 1.410, 95% CI = 1.044-1.906, p = 0.025), but not in Europeans (OR = 0.871, 95% CI = 0.625-1.214, p = 0.415). Furthermore, an association was found between the polymorphism and SLE in Asians using recessive and additive models. However, no association was found between RA and the p53 codon 72 polymorphism in all study subjects or in Europeans. Conclusions: This meta-analysis demonstrates that the p53 codon 72 polymorphism may confer susceptibility to SLE in Asians, but not in Europeans.

No evidence for association of the TP53 12139 and the BAX-248 polymorphisms with endemic pemphigus foliaceus (fogo selvagem)

Pemphigus foliaceus (PF) is an autoimmune bullous epidermal disease, characterized by autoantibodies specific to the desmosomal protein desmoglein 1 (dsg1) and by acantholysis, the rupture of the cellular junctions among keratinocytes. Known also as fogo selvagem (wild fire) in Brazil, the disease has distinct epidemiological characteristics, being endemic in certain regions of South America. It is a multifactorial (complex) disease, with oligo- or polygenic disease susceptibility. In view of the previously reported evidences of a role for apoptosis dysregulation in pemphigus pathogenesis, we hypothesized that genetic variants of molecules participating in apoptosis may contribute to interindividual variation of susceptibility to PF. The TP53 12139(G,C) and the BAX-248(G,A) single nucleotide polymorphisms (SNP) were analysed in a genetic association study. The allelic, genotypic and allele carrier frequencies for these SNPs did not differ statistically between the patient and the control groups, for both the Euro- and the Afro-Brazilian population strata. The results of this study lead us to conclude that, although the TP53 and BAX alleles analysed differ functionally, this variation does not alter the functionality of the molecules in a way that would interfere with the development of the disease.

Association of functional variants of PTPN22 and tp53 in psoriatic arthritis: a case-control study

Recent studies have implicated PTPN22 and tp53 in susceptibility to several autoimmune diseases, including rheumatoid arthritis, suggesting that these genes are important in maintaining immune homeostasis. Because autoimmune diseases may share similar susceptibility loci, investigation of these genes in psoriatic arthritis (PsA) is of potential relevance. As a result we investigated known coding polymorphisms in PTPN22 and tp53 in a homogenous Caucasian PsA cohort from Newfoundland, Canada and an admixed Caucasian PsA cohort from Toronto, Canada. We observed a moderate association of the R620W variant of PTPN22 with PsA in the Toronto population only. Because of the conflicting findings reported regarding the association of PTPN22 with PsA, further studies in other PsA populations are warranted.

Regulation of peripheral blood and synovial fluid lymphocyte apoptosis in juvenile idiopathic arthritis

OBJECTIVE

Complex regulatory mechanisms are involved in the induction of apoptosis. Their impairment may play a role in the pathogenesis of several autoimmune diseases. Recently, we have described higher incidences of spontaneous apoptosis of peripheral blood (PB) lymphocytes in children with juvenile idiopathic arthritis (JIA). This study aimed to evaluate the regulatory mechanisms that may be responsible for this phenomenon.

METHODS

Thirty-four JIA children were examined and compared with 20 healthy children of similar ages. Expression of regulatory proteins p53, Bax and Bcl-2 in lymphocytes isolated from PB and synovial fluid (SF) was assessed. Serum and SF levels of interleukin-15 (IL-15) were also evaluated.

RESULTS

The study showed significantly decreased Bcl-2 expression in JIA PB lymphocytes, compared to both healthy control (p = 0.03) and JIA SF lymphocytes (p = 0.005). There were no significant differences found in Bax expression between groups or compartments examined. However, the Bax/Bcl-2 ratio was nearly two-fold higher in PB lymphocytes than in SF of JIA patients (p = 0.001). p53 expression in PB lymphocytes from both JIA and control children did not statistically differ. In JIA, however, p53 was significantly higher in PB than SF lymphocytes (p = 0.016). IL-15 levels were about 20-fold higher in JIA SF than in serum from either JIA or healthy children (p < 0.0001).

CONCLUSION

The results suggest that a higher incidence of apoptosis of PB lymphocytes observed in JIA may be associated with down-regulation of Bcl-2, rather than with changes in expression of Bax and p53. In contrast, the low p53 expression and elevated IL-15 appear to provide mechanisms responsible for suppression of apoptosis in SF cells from JIA patients.

Tumor suppressor protein p53 and anti-p53 autoantibodies in pediatric rheumatological diseases

The tumor suppressor protein p53 plays an important role in cell cycle regulation. One of the major features in rheumatic diseases is the abnormal proliferation of lymphocytes. p53 expression in peripheral blood mononuclear cells (by flowcytometry) and serum anti-p53 antibodies (by ELISA) were therefore measured in 18 children and adolescents with juvenile rheumatoid arthritis (JRA) and 17 with systemic lupus erythematosus (SLE) in comparison to 20 healthy controls, to determine their role. p53 expression in patients was insignificantly higher than that of controls (2.28 +/- 2.71% vs. 1.08 +/- 1.02%, respectively, p > 0.05) with 29.4% of the patients showing values above a cut-off level of 2.55% (95th percentile of controls). SLE patients with active disease had significantly higher p53 expression compared to controls and to patients with quiescent disease although no significant correlation with ESR or complement 3 was detected. Seropositivity to anti-p53 antibodies was observed in none of controls but in 22.8% of patients, all of whom, except one, had active disease. Seropositivity to anti-p53 antibodies was more prominent in lupus nephritis than in other presentations of SLE (p < 0.05). The mean p53 expression in seropositive patients was insignificantly higher than in seronegatives. p53 expression and seropositivity to anti-p53 were slightly higher in SLE than in JRA and were not significantly affected by the mode of therapy. Thus, the overexpression of p53 in some patients with active SLE and JRA might explain the abnormal proliferation of autoreactive lymphocytes that perpetuates the inflammatory response. The presence of anti-p53 antibodies might cause malfunctioning of p53 protein interfering with its regulatory functions.

p53, proto-oncogene and rheumatoid arthritis

OBJECTIVE

To review the literature published in the past 6 years concerning the role of p53 tumor-suppressor protein in rheumatoid arthritis (RA).

METHODS

A MEDLINE search was performed to identify all publications that covered the role of p53 in RA. In addition, selected articles related to proto-oncogenes and matrix metalloproteinases were included in this review.

RESULTS

p53 protein is expressed in RA fibroblast-like synoviocytes (FLSs), and its overexpression is a characteristic feature of RA. The overexpression of p53 is probably induced by DNA strand breaks caused by the genotoxic environment of RA joints, in some cases because of p53 mutations. Independent studies from 3 groups indicated that p53 mutations can and do occur in RA synovial tissue samples derived from a subset of RA patients. Inactivation of p53 may contribute to the invasiveness of FLSs and to the high-level expression of cartilage degradation enzymes as well. Gene transfer or gene knockout studies using a collagen-II-induced RA animal model to examine the role of p53 in RA have been reported. Initial results are positive and indicate that gene transfer of p53 may be clinically useful for the management of RA.

CONCLUSIONS

p53 protein is expressed in RA FLSs, and its overexpression is a characteristic feature of RA. p53 mutations occur in the synovial tissues derived from a subset of RA patients. The clinical implications of p53 expression and the functional importance of somatic mutations in RA, however, are still unclear. Further research is needed to fully understand the implications of these findings and develop corresponding new therapeutic strategies.