Failure of conventional treatment and losartan in Camurati-Engelmann disease: A case report

Aberrant activation of TGF-β1 induces high bone turnover via Rho GTPases-mediated cytoskeletal remodeling in Camurati-Engelmann disease

In the adult skeleton, the bone remodeling process involves a dynamic coordination between osteoblasts and osteoclasts, which is disrupted in diseases with high bone turnover rates and dysregulated transforming growth factor beta 1 (TGF-β1). However, little is known about how TGF-β1 signaling mediates bone resorption. Here, we described a pedigree with a heterozygous variant in TGF-β1 (R218C) that resulted in aberrant activation of TGF-β1 through an activating mechanism that caused Camurati-Engelmann disease (CED). We showed that CED patients have high levels of active Rho GTPases and the migration-related proteins Integrin β1 and Integrin β3 in their peripheral blood. HEK293T cells transfected with a plasmid encoding this mutant expressed high levels of TGF-β1 and active Rho GTPases. Furthermore, activation of Rho by TGF-β1 increased osteoclast formation and bone resorption, with increased migration of pre-osteoclasts, as well as cytoskeletal remodeling of pre-osteoclasts and mature osteoclasts. Importantly, pharmacological inhibition of Rho GTPases effectively rescued hyperactive TGF-β1-induced osteoclastogenesis in vitro. Overall, we propose that Rho GTPases mediate TGF-β1-induced osteoclastogenesis and suggest that Rho-TGF-β1 crosstalk is associated with high bone turnover in CED.

Improvement of Bone Health and Initiation of Puberty Development in Camurati-Engelmann Disease With Glucocorticoid and Losartan Treatment: A Case Report and Review of Literature

Camurati-Engelmann Disease (CED) is a rare sclerosing bone disease, sometimes associated delayed puberty. The treatment effect of glucocorticoid and angiotensin II receptor blocker (ARB) in bone health and puberty development remain unclear. We report a case of an 18-year-old girl who presented for a history of an enlarged head, pain of lower limbs, and no menstrual onset or breast development. Radiographs revealed thickening of skull and cortices in the diaphysis but sparse bone trabeculae in the spine and metaphysis. Sanger sequencing detected a mutation of c. 652C>T (p. R218C) in the gene TGFB1 and confirmed the diagnosis of CED. After treatment of a medium-to-small dosage of prednisone and losartan for 28 months, we observed improvement of bone mass in spine and hip and body fat mass and found initiation of puberty development. By a systemic review of current treatment strategies in patients with CED, we found that most cases reported relief of bone pain with treatment of glucocorticoid or ARB, but none has reported the outcome of hypogonadotropic hypogonadism. We propose that long-term use of glucocorticoid combined with ARB may inhibit the activation of TGFβ1 in CED, improve adipogenesis, and thus initiate puberty development and improve the bone mass in spine and hip.

Losartan as a Steroid-Sparing Adjunct in a Patient With Features of Refractory Camurati-Engelmann Disease

Objective

The treatment of Camurati-Engelmann disease (CED) involves the use of glucocorticoids, analgesics, and bisphosphonates; experience with the use of losartan is limited. Our objective was to describe the case of a patient diagnosed with CED whose symptoms remained refractory while on steroids and bisphosphonates and who was successfully treated with losartan.

Case Report

A 27-year-old woman presented with bone pain involving her extremities and large joints for 1 year. Clinical examination revealed bone tenderness and proximal myopathy with elevated C-terminal peptide of type 1 collagen (1617 pg/mL; normal range, 137-573 pg/mL) and N-terminal propeptide of type 1 procollagen levels (163 ng/mL; normal range, 5.1-58.3 ng/mL). Calcium (9.4 mg/dL; normal range, 8.3-10.4 mg/dL), phosphate (3.4 mg/dL; normal range, 2.5-4.5 mg/dL), and parathyroid hormone (62 pg/mL; normal range, 8-80 pg/mL) levels were within the normal range. Radiographs showed hyperostosis involving the diaphyseal region of long bones of the lower and upper limbs, and a provisional diagnosis of CED was made. She was treated with prednisolone, 30 mg daily, with which she reported some improvement. As exogenous Cushing syndrome had developed in her because of prednisolone, its dose was tapered. Subsequently, her bone pain worsened. Thereafter, she was initiated on oral alendronate. Due to persistent pain, losartan was added, after which she had marked decrease in bone pain with a reduction in the C-terminal peptide of type 1 collagen (375 pg/mL) and N-terminal propeptide of type 1 procollagen (50 ng/mL) levels.

Discussion

Occasionally, CED presents therapeutic challenges, and when its symptoms remain refractory to conventional doses of steroids and bisphosphonates, other options may be needed. The abovementioned patient was initiated on losartan, which acts by downregulation of transforming growth factor β1, leading to the reduction in pain.

Conclusion

Losartan downregulates transforming growth factor β1 and may be offered as a steroid-sparing option in individuals diagnosed with CED if symptoms remain refractory to conventional treatment.

Sclerosing bone dysplasias

The group of sclerosing bone dysplasia's is a clinically and genetically heterogeneous group of rare bone disorders which, according to the latest Nosology and classification of genetic skeletal disorders (2015), can be subdivided in three subgroups; the neonatal osteosclerotic dysplasias, the osteopetroses and related disorders and the other sclerosing bone disorders. Here, we give an overview of the most important radiographic and clinical symptoms, the underlying genetic defect and potential treatment options of the different sclerosing dysplasias included in these subgroups.