Growth-plate cartilage in chronic renal failure

[Growth hormone - 30 years of clinical practice: past, present, future]

The recombinant technologies era, which began in the second half of the XX century, made it possible to produce recombinant growth hormone (rGH) necessary for the treatment of stunting of various genesis. The time of practically unlimited possibilities of rGH production has come, which served as a stimulus for studying the efficacy and safety of rGH application, searching for optimal ways of its use and dosing regimes. Many years of experience in the use of somatropin in clinical practice allowed us to obtain data on its effectiveness primarily in somatotropic insufficiency in children, to study its effect on the functional state of various organs and systems, and to expand the indications for the use of RGR.

Disease-modifying interactions between chronic kidney disease and osteoarthritis: a new comorbid mouse model

OBJECTIVE

The prevalence of comorbid chronic kidney disease (CKD) and osteoarthritis (OA) is increasing globally. While sharing common risk factors, the mechanism and consequences of concurrent CKD-OA are unclear. The aims of the study were to develop a preclinical comorbid model, and to investigate the disease-modifying interactions.

METHODS

Seventy (70) male 8-10 week-old C57BL/6 mice were subjected to 5/6 nephrectomy (5/6Nx)±destabilisation of medial meniscus (DMM) or sham surgery. OA pathology and CKD were assessed 12 weeks postinduction by blinded histology scoring, micro-CT, immunohistochemistry for osteoclast and matrix metalloproteinase (MMP)-13 activity, and serum analysis of bone metabolic markers.

RESULTS

The 5/6Nx model recapitulated characteristic features of CKD, with renal fibrosis and deranged serum alkaline phosphatase, calcium and phosphate. There was no histological evidence of cartilage pathology induced by 5/6Nx alone, however, synovial MMP-13 expression and subchondral bone osteoclastic activity were increased (p<0.05), with accompanying reductions (p<0.05) in subchondral trabecular bone, bone volume and mineral density. DMM significantly (p<0.05) increased tibiofemoral cartilage damage, subchondral bone sclerosis, marginal osteophytes and synovitis, in association with increased cartilage and synovial MMP-13. DMM alone induced (p<0.05) renal fibrosis, proteinuria and increased (p<0.05) 5/6Nx-induced serum urea. However, DMM in 5/6Nx-mice resulted in significantly reduced (p<0.05) cartilage pathology and marginal osteophyte development, in association with reduced subchondral bone volume and density, and inhibition of 5/6Nx-induced subchondral bone osteoclast activation.

CONCLUSION

This study assessed a world-first preclinical comorbid CKD-OA model. Our findings demonstrate significant bidirectional disease-modifying interaction between CKD and OA.

[Somatotropic axis and molecular markers of mineral metabolism in children undergoing chronic peritoneal dialysis]

Growth failure is one of the most relevant complications in children with chronic kidney disease (CKD). Among others, growth hormone (GH) resistance and bone mineral disorders have been identified as the most important causes of growth retardation.

OBJECTIVES

1. To characterize bone mineral metabolism and growth hormone bio-markers in CKD children treated with chronic peritoneal dialysis (PD). 2. To evaluate height change with rhGH treatment.

PATIENTS AND METHOD

A longitudinal 12-month follow-up in prepuberal PD children.

EXCLUSION CRITERIA

Tanner stage >1, nephrotic syndrome, genetic disorders, steroids, intestinal absorption disorders, endocrine disturbances, treatment with GH to the entry of the study. Demographic and anthropometric data were registered. FGF23, Klotho, VitD, IGF-1, IGFBP3, and GHBP were measured to evaluate mineral and growth metabolism.

RESULTS

15 patients, 7 male, age 6.9 ± 3.0 y were included. Time on PD was 14.33 ± 12.26 months. Height/age Z score at month 1 was -1.69 ± 1.03. FGF23 and Klotho: 131.7 ± 279.4 y 125.9 ± 24.2 pg/ml, respectively. 8 patients were treated with GH during 6-12 months, showing a non-significant increase in height/age Z-score during the treatment period. Bivariate analysis showed a positive correlation between Klotho and delta ZT/E, and between GHBP vs growth velocity index (p < .05).

CONCLUSIONS

FGF23 values were high and Klotho values were reduced in children with CKD in PD, comparing to healthy children. Somatotropic axis variables were normal or elevated. rhGH tends to improve height and there is a positive correlation of GHBP and growth velocity in these children.

Ultrasonographic evaluation of the femoral cartilage thickness in patients with chronic renal failure

OBJECTIVE

To investigate the effects of chronic renal failure (CRF) on the distal femoral cartilage thickness by using ultrasonography and to determine the relationship between cartilage thickness and certain disease-related parameters.

DESIGN

Fifty-seven CRF patients (41 male and 16 female) (mean [SD] age, 44.7 [12.1] years) and 60 healthy controls (41 male and 19 female) (mean [SD] age, 43.5 [13.3] years) were enrolled in this study. Demographic and clinical characteristics were recorded. Cartilage thickness measurements were taken from the medial and lateral condyles, and intercondylar areas of both knees.

RESULTS

Groups were similar in terms of age, weight, height, body mass index and gender (all p>0.05). The mean cartilage thickness was found to be less in CRF patients than in controls (statistically significant for medial condyles and intercondylar areas both in right and the left knees [all p<0.05]). Cartilage thickness showed no correlation with eGFR, and with the levels of serum urea, creatinine, calcium, magnesium, phosphor, hemoglobin, uric acid and as well as steroid use (all p>0.05) in CRF patients.

CONCLUSION

In the light of our findings, we imply that patients with CRF have thinner femoral cartilage than healthy controls. This result may support the view that patients with CRF are at increased risk for developing early knee osteoarthritis. Last but not least, clinicians should be aware of the importance of rehabilitation strategies aimed at decreasing onset and progression of knee osteoarthritis in patients with CRF.

Growth hormone in chronic renal disease

Severe growth retardation (below the third percentile for height) is seen in up to one-third children with chronic kidney disease. It is thought to be multifactorial and despite optimal medical therapy most children are unable to reach their normal height. Under-nutrition, anemia, vitamin D deficiency with secondary hyperparathyroidism, metabolic acidosis, hyperphosphatemia, renal osteodystrophy; abnormalities in the growth hormone/insulin like growth factor system and sex steroids, all have been implicated in the pathogenesis of growth failure. Therapy includes optimization of nutritional and metabolic abnormalities. Failure to achieve adequate height despite 3-6 months of optimal medical measures mandates the use of recombinant GH (rGH) therapy, which has shown to result in catch-up growth, anywhere from 2 cm to 10 cm with satisfactory liner, somatic and psychological development.

1,25(OH)2D3 alters growth plate maturation and bone architecture in young rats with normal renal function

Whereas detrimental effects of vitamin D deficiency are known over century, the effects of vitamin D receptor activation by 1,25(OH)₂D₃, the principal hormonal form of vitamin D, on the growing bone and its growth plate are less clear. Currently, 1,25(OH)₂D₃ is used in pediatric patients with chronic kidney disease and mineral and bone disorder (CKD-MBD) and is strongly associated with growth retardation. Here, we investigate the effect of 1,25(OH)₂D₃ treatment on bone development in normal young rats, unrelated to renal insufficiency. Young rats received daily i.p. injections of 1 µg/kg 1,25(OH)₂D₃ for one week, or intermittent 3 µg/kg 1,25(OH)₂D₃ for one month. Histological analysis revealed narrower tibial growth plates, predominantly in the hypertrophic zone of 1,25(OH)₂D₃-treated animals in both experimental protocols. This phenotype was supported by narrower distribution of aggrecan, collagens II and X mRNA, shown by in situ hybridization. Concomitant with altered chondrocyte maturation, 1,25(OH)₂D₃ increased chondrocyte proliferation and apoptosis in terminal hypertrophic cells. In vitro treatment of the chondrocytic cell line ATDC5 with 1,25(OH)₂D₃ lowered differentiation and increased proliferation dose and time-dependently. Micro-CT analysis of femurs from 1-week 1,25(OH)₂D₃-treated group revealed reduced cortical thickness, elevated cortical porosity, and higher trabecular number and thickness. 1-month administration resulted in a similar cortical phenotype but without effect on trabecular bone. Evaluation of fluorochrome binding with confocal microscopy revealed inhibiting effects of 1,25(OH)₂D₃ on intracortical bone formation. This study shows negative effects of 1,25(OH)₂D₃ on growth plate and bone which may contribute to the exacerbation of MBD in the CKD pediatric patients.