Early predictors of increased bone resorption in juvenile idiopathic arthritis: OPG/RANKL ratio, as a key regulator of bone metabolism

Bone mineral density in egyptian children with juvenile idiopathic arthritis: possible correlation to serum RANKL / osteoprotegerin (OPG) ratio and OPG gene polymorphisms

BACKGROUND

Children with juvenile idiopathic arthritis (JIA) are at higher risk of decreased bone mineral density (BMD) compared with healthy children due to genetic, disease and medication-related causes. This study aims to investigate the possible effects of osteoprotegerin (OPG) gene polymorphisms and serum levels of osteoprotegerin (OPG) and receptor activator of nuclear factor κB-ligand (RANKL) and RANKL/OPG ratio on BMD in children with JIA.

METHODS

OPG gene rs2073617, rs3134069, serum RANKL, OPG and RANKL/OPG ratio were evaluated in 60 JIA children and 100 matched healthy controls. BMD was evaluated by lumbar dual energy X-ray absorptiometry (DEXA) according to which patients were classified in 2 groups (DEXA z-score above and below - 2). Composite disease activity was measured using the Juvenile Arthritis Disease Activity Score (JADAS) 27-joints. Articular damage was scored using the juvenile arthritis damage index (JADI).

RESULTS

Patients aged 12.05 ± 3.2 years, included 38 females and 31% had BMD z-score below-2. Systemic-onset JIA was the most frequent phenotype (38%). Genotypes and alleles frequencies of the 2 studied polymorphisms did not differ between patients and controls (p > 0.05 for all) while serum RANKL and RANKL/OPG ratio were significantly higher in patients compared to controls (p = < 0.001 and 0.03 respectively). Patients with BMD < -2 had significantly greater frequencies of rs2073617 TT genotype and T allele (p < 0.001), higher serum RANKL, RANKL/OPG ratio (p = 0.01, 0.002), female predominance (p = 0.02), higher articular and extra-articular damage index (p = 0.008,0.009) and more frequent steroid usage (p = 0.02) compared to patients with BMD z-score >-2. Multivariate analysis showed rs2073617 TT genotype, RANKL/OPG ratio, long disease duration (above 36 months) and use of steroid to be associated with decreased BMD (p = 0.03,0.04,0.01,0.01 respectively) in JIA children.

CONCLUSIONS

Egyptian children with JIA have decreased BMD. rs2073617 TT genotype and T allele, RANKL/OPG ratio are possible determinants of reduced BMD in JIA. Our results underline the importance of frequent monitoring of BMD in JIA children and trying to control disease activity to preserve long term bone health.

Predictors of decreased bone mineral density in childhood systemic lupus erythematosus: possible role of osteoprotegerin gene polymorphisms

OBJECTIVES

This study aims to explore effects of osteoprotegerin (OPG) gene polymorphisms and other possible factors on bone mineral density (BMD) in children with systemic lupus erythematosus (SLE).

METHODS

Osteoprotegerin gene rs2073617 and rs3134069 were evaluated in 74 SLE patients and 100 controls then genotypes, alleles and haplotypes' frequencies were compared between cases and controls and between patients with BMD z-scores above and below -2 evaluated by dual energy X-ray absorptiometry (DEXA). Disease activity was evaluated by SLE disease activity index (SLEDAI).

RESULTS

The patients aged 14.01 ± 2.6 years and included 57 (77%) females and 27 (36%) patients with BMD z-score below -2. Genotypes, alleles, and haplotypes frequencies did not differ between patients and controls (p>0.05 for all). Rs3134069 GG genotype and G allele (p=0.001, 0.002) and rs2073617 TT genotype and T allele (p=0.01, 0.006) were significantly higher in patients with BMD below -2. Cumulative glucocorticoids dose, disease duration, and SLEDAI scores were higher in patients with BMD below -2 (p=0.01, 0.01, <0.001, respectively). Regression analysis showed T allele of rs2073617, duration of illness (above 36 months), and cumulative SLEDAI (above 10) as independent predictors of decreased BMD (p 0.02, 0.003, and 0.002, respectively).

CONCLUSIONS

This is the first study to demonstrate OPG gene influence on BMD in children with SLE. The studied SNPs are not risk for developing SLE but, rs2073617 T allele is a possible predictor for reduced BMD in SLE. Other predictors include long disease duration and high activity supporting that osteoporosis in SLE is multifactorial.

Methotrexate Hepatotoxicity in Children with Juvenile Idiopathic Arthritis: A Single-Center Study

BACKGROUND

Juvenile idiopathic arthritis (JIA) could be disabling if left untreated. Methotrexate (MTX) is well known as a cornerstone in management. However, its adverse effects may limit treatment.

OBJECTIVE

The objective of this study was to evaluate the frequency of hepatotoxicity based on liver chemistry in JIA children receiving MTX.

METHODS

An observational case-control study of children with JIA who attend the Pediatric Rheumatology Unit, Cairo University Pediatric Hospital, Egypt, from January 2018 to December 2018 was carried out. Data were retrieved for 80 children; 50 (62.5%) were prescribed MTX. Their demographic, clinical characteristics, mean dose, duration of MTX therapy and other medications were described. Hepatotoxicity was defined as at least one value above the normal laboratory range of either ALT or AST during the study period.

RESULTS

Fourteen patients developed hepatotoxicity, giving an incidence of 28%. Children receiving MTX had higher alanine aminotransferase (ALT) interquartile range (IQR) (26 [21-359] vs. 23[20-32]; p =0.003), higher aspartate aminotransferase (AST) interquartile range (IQR) (31 [22-267] vs. 28[2-35] IU/L; p <0.001), and lower alkaline phosphatase (ALP) mean (±SD) (98±35.5 vs. 256 ± 39.5 IU/L; p <0.001). However, there were no significant differences in age, sex, weight, type of JIA, and duration of MTX treatment (p< 0.05).

CONCLUSION

Hepatotoxicity due to MTX, based on liver chemistry, is common among children with JIA.

Serum RANKL, osteoprotegerin (OPG) and RANKL/OPG ratio in children with systemic lupus erythematosus

Background

Systemic lupus erythematosus (SLE) patients have lower bone mineral density (BMD) compared with healthy individuals because of general, genetic, disease and medication-related factors. The disturbance of the receptor activator of nuclear factor-κB ligand (RANKL)/osteoprotegerin (OPG) ratio has been reported to be associated with low BMD in many disorders in adults and children alike.

Objectives

The objectives of this study were (i) to assess serum OPG, RANKL and RANKL/OPG ratio levels in SLE children and controls, (ii) to determine whether the cumulative glucocorticoid (CGCS) dose had any effect on the concentration of serum RANKL, OPG and RANKL/OPG ratio, and (iii) to determine the relation of these parameters to BMD.

Methods

We evaluated 50 SLE children and 50 age- and sex-matched healthy controls. RANKL and OPG were assessed in serum and compared between patients and controls. For SLE patients, a univariate followed by multivariable analysis were carried out to detect the possible predictors of the changes in RANKL, OPG and RANKL/OPG ratio levels. Lumbar BMD for all patients was assessed by dual-energy X-ray absorptiometry (DXA) scan and then correlated to different probable correlated factors.

Results

RANKL, OPG and RANKL/OPG ratio were significantly higher in SLE patients ( p ≤ 0.001). Univariate analysis showed significant correlations of RANKL with CGCS ( p ≤ 0.001) and with DXA scan z-score ( p = 0.007): OPG was significantly correlated to Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score ( p = 0.001) and anti-double-stranded DNA ( p = 0.001), whereas RANKL/OPG was significantly correlated to duration of illness and DXA z-score ( p = 0.002). The multivariable analysis showed that DXA z-score was an independent predictor of RANKL and RANKL/OPG ratio ( p = 0.019 and 0.008, respectively), whereas SLEDAI score was an independent predictor of OPG levels. BMD was negatively correlated to disease duration ( p = 0.008) and CGCS dose ( p = 0.015), but no significant correlation has been found between BMD and cumulative SLEDAI score ( p = 0.29).

Conclusions

Serum RANKL/OPG ratio is elevated in Egyptian children with SLE and is considered a risk factor for reduced bone mass in these children. Other risk factors for low BMD include high CGCS dose and disease duration, supporting that osteoporosis in SLE is multifactorial.

Rheumatology in Egypt: back to the future

Medical knowledge in ancient Egypt had a remarkable reputation since rulers of other empires used to request the pharaoh to send them their best physician to treat their beloved ones. Many rheumatologic conditions as giant-cell arteritis, reactive arthritis and other forms of spondyloarthritis have been identified in ancient Egyptian materials. Rheumatologists in Egypt are enormously expanding and mastering the tools that aid them in enhancing the management of rheumatic diseases. More Egyptian rheumatologists are actively participating in the annual European League Against Rheumatism (EULAR) and American College of Rheumatology conferences and those attached to well known state of the art centers are increasing. EULAR certified Egyptian MSUS trainers are effectively performing regionally. This review throws light on the rheumatology practice in Egypt, its progress from ancient times passing through Egyptian medical healthcare services, education systems for rheumatologists, rheumatology associations, an overview on the spectrum of rheumatic diseases through publications in the field till future perspectives. Rheumatology in Egypt is an actively growing and dynamic specialty of medicine with considerable contributions to the world's literature. These days, persistent efforts are mandatory to raise the standard of clinical and basic research, to optimize clinical practice with regard to new biologics, to develop tailored and targeted therapies for the rheumatic diseases, and to meet the medical demands of the exponentially increasing Egyptian population. Opportunities and challenges discussed high-lighten future perspectives needed to boost the rheumatology practice in Egypt.