Effects of cyclosporin A on sex hormone and estrogen receptor in male rat with special reference to cyclosporin A-induced osteoporosis

Advances in the interaction between endoplasmic reticulum stress and osteoporosis

The endoplasmic reticulum (ER) is the main site for protein synthesis, folding, and secretion, and accumulation of the unfolded/misfolded proteins in the ER may induce ER stress. ER stress is an important participant in various intracellular signaling pathways. Prolonged- or high-intensity ER stress may induce cell apoptosis. Osteoporosis, characterized by imbalanced bone remodeling, is a global disease caused by many factors, such as ER stress. ER stress stimulates osteoblast apoptosis, increases bone loss, and promotes osteoporosis development. Many factors, such as the drug's adverse effects, metabolic disorders, calcium ion imbalance, bad habits, and aging, have been reported to activate ER stress, resulting in the pathological development of osteoporosis. Increasing evidence shows that ER stress regulates osteogenic differentiation, osteoblast activity, and osteoclast formation and function. Various therapeutic agents have been developed to counteract ER stress and thereby suppress osteoporosis development. Thus, inhibition of ER stress has become a potential target for the therapeutic management of osteoporosis. However, the in-depth understanding of ER stress in the pathogenesis of osteoporosis still needs more effort.

Effects of denosumab on bone metabolism and bone mineral density in kidney transplant patients: a systematic review and meta-analysis

OBJECTIVE

The use of immunosuppressive agents, especially glucocorticoids, are associated with increased risks of bone loss in kidney transplant patients. Denosumab, a potent antiresorptive agent, has been shown to increase bone mineral density (BMD) in patients with CKD. However, its effects on bone metabolism and BMD in kidney transplant patients remain unclear.

METHODS

A literature search was conducted using MEDLINE, EMBASE, and Cochrane Database from inception through April 2018 to identify studies evaluating denosumab's effect on changes in bone metabolism and BMD from baseline to post-treatment course in kidney transplant patients. Study results were pooled and analyzed utilizing random-effects model. The protocol for this systematic review is registered with PROSPERO (International Prospective Register of Systematic Reviews; no. CRD42018095055).

RESULTS

Five studies (a clinical trial and four cohort studies) with a total of 162 kidney transplant patients were identified. The majority of patients had a baseline eGFR ≥ 30 mL/min/1.73 m². After treatment (≥ 6 to 12 months), there were significant increases in BMD with standardized mean differences (SMDs) of 3.26 (95% CI 0.88-5.64) and 1.83 (95% CI 0.43 to 3.22) for lumbar spine and femoral neck, respectively. There were also significant increases in T scores with SMDs of 0.92 (95% CI 0.58 to 1.25) and 1.14 (95% CI 0.17 to 2.10) for lumbar spine and femoral neck, respectively. After treatment, there were no significant changes in serum calcium (Ca) or parathyroid hormone (PTH) from baseline to post-treatment course (≥ 6 months) with mean differences (MDs) of 0.52 (95% CI, - 0.13 to 1.16) mmol/L and - 13.24 (95% CI, - 43.85 to 17.37) ng/L, respectively. The clinical trial data demonstrated more asymptomatic hypocalcemia in the denosumab (12 episodes in 39 patients) than in the control (1 episode in 42 patients) group. From the cohort studies, the pooled incidence of hypocalcemia following denosumab treatment was 1.7% (95% CI 0.4 to 6.6%). All reported hypocalcemic episodes were mild and asymptomatic, but the majority of patients required Ca and vitamin D supplements.

CONCLUSION

Among kidney transplant patients with good allograft function, denosumab effectively increases BMD and T scores in the lumbar spine and femur neck. From baseline to post-treatment, there are no differences in serum Ca and PTH. However, mild hypocalcemia can occur following denosumab treatment, requiring monitoring and titration of Ca and vitamin D supplements.

Relationship Between Immunosuppression and Osteoporosis in an Outpatient Liver Transplant Clinic

BACKGROUND

The aim of this study is to determine the relationship between immunosuppression, disease state, and osteoporosis in an outpatient liver transplant clinic.

METHODS

All liver transplant recipients visiting an outpatient transplant clinic received bone density scanning with a dual-energy X-ray absorptiometry (DEXA) device of the calcaneal bone after completing a questionnaire assessing risk and medications currently being used.

RESULTS

Of the 137 liver transplant (OLT) recipients completing questionnaires and receiving DEXA screening, patients with low bone density (n = 50) were older (56.6 +/- 12.7 years vs 50.2 +/- 10.1 years; P = .02) compared with normal density patients (n = 87) and were predominately female (64.0% vs 35.6%; P = .01). Based on disease state, patients with cholestatic liver failure had lower bone calcaneal area (17.3 +/- 1.3 cm2 vs 18.9 +/- 1.57 cm2; P < .01). Patients taking tacrolimus (n = 112), as compared with cyclosporine (n = 25), had a tendency toward fewer findings of low bone density (37.5% [42 of 112] vs 56.0% [14 of 25]; P = .08) but had more risk factors (3.1 +/- 1.2 vs 2.1 +/- 0.8; P = .001) and a higher prednisone dose (4.4 +/- 5.9 mg/d vs 2.1 +/- 3.8 mg/d; P = .026). For patients weaned from prednisone, the tacrolimus patients were less likely to have low bone density (36.2% vs 68.8%; P = .02). Mycophenolate mofetil did not influence bone density or area measured.

CONCLUSIONS

After liver transplantation, patients taking cyclosporine were more likely to have low bone density compared with those taking tacrolimus.

Pathogenesis of bone loss in heart transplant candidates and recipients

BACKGROUND

Heart transplantation (HTX) is associated with decreased bone mineral density and changes in bone metabolism. We conducted this study to evaluate the pathophysiology of bone metabolism in HTX candidates and recipients.

METHODS

Thirty-six HTX recipients were compared with 36 HTX candidates concerning biochemical parameters of bone metabolism and bone mineral density.

RESULTS

Osteocalcin, bone-specific alkaline phosphatase, cross-linked-N-telopeptide of type I collagen, estradiol, serum creatinine, and blood urea nitrogen concentrations were significantly higher, whereas the calcium-creatinine ratio, thyrotropin, thyroxine, and bone mineral density were significantly lower in HTX recipients than in HTX candidates. Compared with a control group, HTX candidates had decreased renal function and increased bone resorption, whereas HTX recipients additionally had increased alkaline phosphatase and osteocalcin levels. In HTX recipients, we found positive correlations between creatinine clearance and bone mineral density; daily and cumulative cortisone doses were not associated with bone mineral density.

CONCLUSIONS

In HTX candidates, disturbances in bone metabolism with increased bone resorption may be caused partly by existing low-grade renal insufficiency, regular intake of loop diuretics, and restriction of mobility. In HTX recipients, immunosuppressive therapy-glucocorticoids and cyclosporine-seem to be responsible for changes in bone metabolism.