Teriparatide (recombinant human parathyroid hormone [1-34]) increases foot bone remodeling in diabetic chronic Charcot neuroarthropathy: a randomized double-blind placebo-controlled study

Therapeutics of Charcot neuroarthropathy and pharmacological mechanisms: A bone metabolism perspective

Charcot neuroarthropathy (CN) is a chronic, destructive, and painless damage of the skeletal system that affects the life quality of patients. CN, with an unclear mechanism, is characterized with invasive destruction of bones and a serious abnormality of bone metabolism. Unfortunately, development of an effective prevention and treatment strategy for CN is still a great challenge. Of note, recent studies providing an insight into the molecular mechanisms of bone metabolism and homeostasis have propelled development of novel CN therapeutic strategies. Therefore, this review aims to shed light on the pathogenesis, diagnosis, and treatment of CN. In particular, we highlight the eminent role of the osteoprotegerin (OPG)-receptor activator of nuclear factor-κB (RANK)-RANK ligand (RANKL) system in the development of CN. Furthermore, we summarize and discuss the diagnostic biomarkers of CN as well as the potential pharmacological mechanisms of current treatment regimens from the perspective of bone metabolism. We believe that this review will enhance the current state of knowledge on the diagnosis, prevention, and therapeutic efficacy of CN.

The role of the Wnt signalling pathway in the energy metabolism of bone remodelling

OBJECTIVES

Bone remodelling is necessary to repair old and impaired bone caused by aging and its effects. Injury in the process of bone remodelling generally leads to the development of various bone diseases. Energy metabolism plays crucial roles in bone cell formation and function, the disorder of which will disrupt the balance between bone formation and bone resorption.

MATERIALS AND METHODS

Here, we review the intrinsic interactions between bone remodelling and energy metabolism and the role of the Wnt signalling pathway.

RESULTS

We found a close interplay between metabolic pathways and bone homeostasis, demonstrating that bone plays an important role in the regulation of energy balance. We also discovered that Wnt signalling is associated with multiple biological processes regulating energy metabolism in bone cells.

CONCLUSIONS

Thus, targeted regulation of Wnt signalling and the recovery of the energy metabolism function of bone cells are key means for the treatment of metabolic bone diseases.

Long-term foot outcomes following differential abatement of inflammation and osteoclastogenesis for active Charcot neuroarthropathy in diabetes mellitus

AIMS

Inflammatory osteolysis is sine-qua-non of active Charcot neuroarthropathy (CN) causing decreased foot bone mineral density (BMD) and fractures. We aimed to explore the effect of anti-inflammatory or anti-resorptive agents for effect on foot bone mineral content (BMC) and consequent long-term outcomes of foot deformities, fractures and amputation.

METHODS

Forty-three patients with active CN (temperature difference >2°C from normal foot) were evaluated. Patients were off-loaded with total contact cast and randomized to receive either methylprednisolone (1gm) (group A), zoledronate (5mg) (group B) or placebo (100ml normal saline) (group C) once monthly infusion for three consecutive months. Change in foot BMC was assessed at 6 months or at remission and followed subsequently up to 4 years for the incidence of new-onset fracture, deformities, or CN recurrence.

RESULTS

Thirty-six participants (24 male, 12 female) were randomized (11 in group A, 12 group B, 13 group C). The mean age was 57.7± 9.9 years, duration of diabetes 12.3± 5.8 years and symptom duration 6.5± 2.8 weeks. BMC increased by 36% with zoledronate (p = 0.02) but reduced by 13% with methylprednisolone (p = 0.03) and 9% (p = 0.09) with placebo at remission. There were no incident foot fractures, however, two patients sustained ulcers, and 3 had new-onset or worsening deformities and none required amputation during 3.36 ± 0.89 years of follow-up.

CONCLUSION

Bisphosphonate for active CN is associated with an increase in foot bone mineral content as compared to decrease with steroids or total contact cast but long-term outcomes of foot deformities, ulceration and amputation are similar.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT03289338.

Lgr4 promotes aerobic glycolysis and differentiation in osteoblasts via the canonical Wnt/β-catenin pathway

Lgr4, a G-protein-coupled receptor, is associated with various physiological and pathological processes including oncogenesis, energy metabolism, and bone remodeling. However, whether Lgr4 is involved in osteoblasts' metabolism is not clear. Here we uncover that in preosteoblast cell line, lacking Lgr4 results in decreased osteogenic function along with reduced glucose consumption, glucose uptake, and lactate production in the presence of abundant oxygen, which is referred to as aerobic glycolysis. Activating canonical Wnt/β-catenin signaling rescued the glycolytic dysfunction. Lgr4 promotes the expression of pyruvate dehydrogenase kinase 1 (pdk1) and is abolished by interfering canonical Wnt/β-catenin signaling. Mice lacking Lgr4 specifically in osteoblasts (Lgr4^osb-/- ) exhibit decreased bone mass and strength due to reduced bone formation. Additionally, glycolysis of osteoblasts is impaired in Lgr4^osb-/- mice. Our study reveals a novel function of Lgr4 in regulating the cellular metabolism of osteoblasts. © 2021 American Society for Bone and Mineral Research (ASBMR).

Effect of Recombinant Human Parathyroid Hormone (1-84) on Resolution of Active Charcot Neuro-osteoarthropathy in Diabetes: A Randomized, Double-Blind, Placebo-Controlled Study

OBJECTIVE

Fractures in Charcot neuro-osteoarthropathy (CN) often fail to heal despite prolonged immobilization with below-knee casting. The aim of the study was to assess the efficacy of recombinant human parathyroid hormone (PTH) in reducing time to resolution of CN and healing of fractures.

RESEARCH DESIGN AND METHODS

People with diabetes and acute (active) Charcot foot were randomized (double-blind) to either full-length PTH (1-84) or placebo therapy, both in addition to below-knee casting and calcium and vitamin D3 supplementation. The primary outcome was resolution of CN, defined as a skin foot temperature difference >2°C at two consecutive monthly visits.

RESULTS

Median time to resolution was 5 months (95% CI 4, 12) in intervention and 6 months (95% CI 2, 9) in control. On univariate mixed Cox and logistic regression, there was no significant difference in time to resolution between the groups (P = 0.64) or in the likelihood of resolution (P = 0.66). The hazard ratio of resolution was 0.84 (95% CI 0.41, 1.74; P = 0.64), and the odds ratio of resolution by 12 months was 0.80 (95% CI 0.3, 2.13; P = 0.66) (intervention vs. control). On linear regression analysis, there were no significant differences in the effect of treatment on fracture scores quantitated on MRI scans (coefficient 0.13 [95% CI -0.62, 0.88]; P = 0.73) and on foot and ankle X-rays (coefficient 0.30 [95% CI -0.03, 0.63]; P = 0.07).

CONCLUSIONS

This double-blind placebo-controlled trial did not reduce time to resolution or enhance fracture healing of CN. There was no added benefit of daily intervention with PTH (1-84) to below-knee casting in achieving earlier resolution of CN.

An inverted U-shaped relationship between parathyroid hormone and body weight, body mass index, body fat

PURPOSE

To investigate the relationship between parathyroid hormone (PTH) levels and body weight, body mass index (BMI), lipid profiles, and fat distribution in subjects with primary hyperparathyroidism (PHPT) and controls.

METHODS

This was a cross-sectional study in 192 patients with PHPT and 202 controls. Serum concentrations of calcium, 25-hydroxyvitamin D (25(OH)D), PTH, lipids profiles, and other hormones were quantified. Bone mineral density was assessed by dual-energy X-ray absorptiometry. Fat distribution evaluation utilizing quantitative computed tomography was conducted in another 66 patients with PHPT and 155 controls.

RESULTS

PHPT patients were older (P < 0.001) and had less body weight (P < 0.001), lower BMI (P = 0.019), lower serum concentrations of 25(OH)D (P < 0.001), total cholesterol (P = 0.036), low-density lipoprotein-cholesterol (P = 0.036), and higher circulating concentration of free fatty acid (FFA) (P = 0.047) as compared with controls. After adjusting multiple confounders, PTH was positively correlated with weight (r = 0.311, P < 0.001), BMI (r = 0.268, P < 0.01), and visceral adipose tissue area (VAA) (r = 0.191, P < 0.05) in the first tertile of PTH. However, these associations were not observed in the second tertile. While in the third tertile, PTH was negatively correlated with weight (r = -0.200, P < 0.05), BMI (r = -0.223, P < 0.05) and marginally with VAA (r = -0.306, P = 0.065), it showed positive association with FFA (r = 0.230, P < 0.05).

CONCLUSIONS

The inverted U-shape relationship between PTH and body weight, BMI, VAA found in this study is helpful to explain the conflicting results among these parameters, and extend our understanding of the metabolic effects of PTH.

Efficacy of medical treatment for Charcot neuroarthropathy: a systematic review and meta-analysis of randomized controlled trials

No pharmacotherapeutic agents are yet recommended for active CN though many anti-resorptive agents have been studied. We conducted a systematic review and meta-analysis of the randomized placebo-controlled trials (RCTs) evaluating the time to remission of active CN with anti-resorptive or antiinflammatory drugs. RCTs published in PubMed, EMBASE, SCOPUS and Cochrane Library from January 1994 to December 2019 were accessed. We reviewed studies and extracted information on study design, participants' characteristics, time to remission, bone turnover markers, bone mineral content (BMC) and temperature difference between feet. Five RCTs out of 588 total identified records were included. Standardized mean differences (SMD) between groups with 95% CI are summarized. Pharmacotherapy nonsignificantly increased time to remission [SMD 0.52 weeks (- 0.71, 1.75), p = 0.402; I2 = 88.6%] as compared to TCC alone. The pooled median time to remission with the intervention was 18.5 weeks (11.2, 28.1) compared to 16.8 weeks (8.7, 27.7) with TCC. A nonsignificant increase in BMC [SMD 3.39% (- 0.78, 7.56), p = 0.109; I2 = 96.7%], a decrease in foot temperature [SMD - 0.42 °C (- 0.78, - 0.07), p = 0.020; I2 = 0%] and alkaline phosphatase [SMD = -2.51% (- 3.24, - 1.77), p < 0.001; I2 = 0%] was observed with intervention. Limited evidence from available studies does not support the role of anti-resorptive or anti-inflammatory drugs for earlier remission when added to offloading with total contact cast for active CN of the foot.

An overview of Charcot's neuroarthropathy

Charcot's neuroarthropathy is a destructive complication of the joints, which is often found in people with diabetes with peripheral neuropathy. Despite the fact that its description was published almost 130 years ago, its pathophysiology, diagnosis, and treatment remain areas that need to be described. Thanks to the use of bone remodelling, new therapeutic classes have emerged, we hope that this review will shed light on the pathology from its discovery through to the current state of knowledge on its classification, diagnosis and treatment methods.

BMP9 Reduces Bone Loss in Ovariectomized Mice by Dual Regulation of Bone Remodeling

Bone remodeling is dynamic and is tightly regulated through bone resorption dominated by osteoclasts and bone formation dominated by osteoblasts. Imbalances in this process can cause various pathological conditions, such as osteoporosis. Bone morphogenetic protein 9 (BMP9), a biomolecule produced and secreted by the liver, has many pharmacological effects, including anti-liver fibrosis, antitumor, anti-heart failure, and antidiabetic activities. However, the effects of BMP9 on the regulation of osteoblast and osteoclast functions and the underlying molecular mechanism(s) have not yet been investigated. In this study, BMP9 increased the expression of osteoblastogenic gene markers, such as ALP, Cola1, OCN, RUNX2, and OSX, and ALP activity in MC3T3-E1 cells by upregulating LGR6 and activating the Wnt/β-catenin pathway. BMP9 also suppressed receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclast differentiation of bone marrow macrophages (BMMs) by inhibiting the Akt-NF-κB-NFATc1 pathway. More importantly, in an ovariectomy (OVX) mouse model, BMP9 attenuated bone loss and improved bone biomechanical properties in vivo by increasing bone-forming activity and suppressing bone resorption activity. Accordingly, our current work highlights the dual regulatory effects that BMP9 exerts on bone remodeling by promoting bone anabolic activity and inhibiting osteoclast differentiation in OVX mice. © 2020 American Society for Bone and Mineral Research.

Mortality in Asian Indians with Charcot's neuroarthropathy: a nested cohort prospective study

AIMS

We studied mortality in individuals of diabetes with or without Charcot neuroarthropathy (CN).

METHODS

People attending diabetic foot care facility with CN of foot (Cohort 1) were prospectively evaluated. Details pertaining to the duration of diabetes, microvascular and macrovascular complications, foot ulcer, amputation and mortality outcomes were recorded and compared with those without foot complications (Cohort 2) by multivariate logistic regression.

RESULTS

Data for 260 individuals of diabetes with CN and 520 individuals without CN were analysed. Mean age at presentation with CN was 55.8 ± 9.1 years, and duration of diabetes was 12.9 ± 7.8 years. 39.8% individuals with CN had foot ulcer, and 15.3% had amputation. People with CN were younger (55 ± 9.1 vs. 59.9 ± 8.1 years, p < 0.001) and had higher prevalence of microvascular complications. A total of 39 (15%) individuals with CN and 50 (9.8%) (p = 0.03) individuals without CN died during median follow-up of 40(24-51) months. People with CN had 2.7 times (OR 2.72, 95% CI 1.4-5.2, p = 0.003) increased mortality risk when matched for potential confounders. Prevalent CAD and low eGFR predicted higher mortality in people with CN.

CONCLUSIONS

People with Charcot neuroarthropathy have almost three times increased risk of mortality despite being younger at presentation.