Bowen Wang

Background: Intervertebral disc degeneration (IVDD) is a major cause of global disability that increases with age. IVD age may affect its injury susceptibility, yet few studies examine spine biomechanical changes with age, fewer address multiple injury types, and none investigate the interplay between age and injury. Methods: An ex vivo mouse lumbar spine biomechanical study to determine the effects of age, injury, and their interaction. IVDs of 4, 12, and 24 months' mice were subjected to two injury types: Full disc puncture (DP) mimicking advanced IVDD and annulus fibrosus and endplate (AF + EP) injury simulating herniation with endplate junction failure. Spines were tested biomechanically, analyzed radiologically for IVD dimensions, and with FTIR and histology for biochemical content. Results: Both age and injury significantly altered biomechanical properties of IVDs. Injury had a greater effect than age, and DP caused larger changes than AF + EP injury. Injury and age exhibited an interactive effect, resulting in more pronounced biomechanical dysfunction in middle‐aged (12 months) and geriatric IVDs (24 months), likely due to age‐related loss of proteoglycans and collagen denaturation shown with FTIR and histology. Conclusions: We conclude that both age and injury independently and synergistically affect ex vivo biomechanical properties of mouse lumbar spine. The more severe biomechanical change in middle‐aged and geriatric mouse lumbar spines suggests similar injuries may cause greater spinal dysfunction in individuals of comparable ages. These findings provide context for future in vivo studies investigating long‐term effects of acute spine injuries.

Disruptions of the composition of the gut microbiome are linked to impaired bone tissue strength. Fecal microbiota transplantation (FMT) is an established clinical therapy that can restore a healthy gut microbiome and reduce systemic inflammation. However, whether FMT from a healthy donor could rescue bone fragility is unknown. As induced inflammation causes mineralization defects, we hypothesize that manipulations of the gut microbiota alter bone fracture resilience through changes in mineral quality. Here, we altered the compositions of the gut microbiome in mice via antibiotics (ampicillin and neomycin) and FMT. Mice were allocated to 5 groups (M/F, N = 13-18/group): Unaltered, Continuous (dosed 4-24 wk), Initial (dosed 4-16 wk), Reconstituted (dosed 4-16 wk with subsequent FMT from age- and sex-matched mice with unaltered gut microbiota), and Delayed (dosed 16-24 wk). Fracture toughness testing and Raman spectroscopy were conducted on the femora. The maximum toughness was greater in the Reconstituted group (for females, p < .05 compared to Continuous, Unaltered, and Delayed groups; for males, p < .05 compared to groups with antibiotic dosing). The Reconstituted group showed lower type-B carbonate substitution in the bone mineral (all p < .01 for both sexes), and lower mineral-to-matrix ratio (all p < .01 for males, for females, p < .01 compared to Unaltered, Initial, and Delayed groups). In females, mineral crystallinity was higher in the Reconstituted group than those dosed with antibiotics (all p < .05). Serum inflammation marker TNF-α was positively correlated with type-B carbonate substitutions (ρ = 0.66), mineral-to-matrix ratio (ρ = 0.71), and carboxymethyl-lysine (CML) in bone matrix (ρ = 0.43). Enhanced bone maximum fracture toughness was associated with reduced type-B carbonate substitution (r = −0.45), decreased mineral-to-matrix ratio (r = −0.40), increased mineral crystallinity (r = 0.33), and lower levels of bone CML (r = −0.49, all p < .01). These results suggest that the introduction of more beneficial gut microbiota can increase fracture resistance by modifying mineral composition and quality, likely through the reduction of systemic inflammation.

Context Type 2 diabetes (T2D) patients have reduced bone turnover and increased fractures. Advanced glycation endproducts (AGEs) impair osteoblasts and are implicated in diabetic fractures. Pyridoxamine (PM) is a vitamin B₆ metabolite which inhibits formation of AGEs. Objective We hypothesized that PM treatment in older T2D patients, by inhibiting AGEs, would increase bone formation. Design Double-blind RCT. Setting Academic center. Participants Older T2D women (n=55). Intervention Oral PM 200 mg twice daily for one year. Main Outcomes The primary outcome was the change in the bone formation marker P1NP. Other outcomes were changes in bone resorption, bone mineral density (BMD), HbA1c and skin autofluorescence (SAF), and in a bone biopsy sub-group, the correlation between bone fluorescent AGEs (fAGEs) and SAF. Results P1NP increased 23.0% with PM (95% CI: 9, 37; within-group p=0.028) vs. 4.1% with placebo (-9, 17; within-group p=0.576; between-groups p=0.056). BMD increased at the femoral neck (PM: 2.6±5% vs. placebo: -0.9±4%; between-groups p=0.007). Bone resorption markers and SAF did not change. HbA1c decreased (PM: -0.38 ± 0.7% vs. placebo: 0.05 ± 1.7%; between-groups p =0.04). Within the PM group, the HbA1c change correlated inversely with the % P1NP change (r =-0.50, p=0.034). Cortical bone biopsy fAGEs correlated with SAF (r=0.86, p=0.001). Adverse events were similar between groups. Conclusion PM tended to increase P1NP in older T2D women, as well as increasing bone density and reducing HbA1c. Further studies are needed to investigate the potential of PM as a disease mechanism-directed approach to reduce fractures in T2D.

Context Fracture risk is underestimated in people with type 2 diabetes (T2D). Objective To investigate the longitudinal relationship of glycated hemoglobin (HbA1c) and common medications on fracture risk in people with T2D. Methods This retrospective population-based cohort study was conducted using de-identified claims and electronic health record data obtained from the OptumLabs Data Warehouse for the period January 1, 2007, to September 30, 2015. For each individual, the study was conducted within a 2-year HbA1c observation period and a 2-year fracture follow-up period. A cohort of 157 439 individuals with T2D [age ≥ 55 years with mean HbA1c value ≥ 6%] were selected from 4 018 250 US Medicare Advantage/Commercial enrollees with a T2D diagnosis. All fractures and fragility fractures were measured. Results With covariates adjusted, poor glycemic control in T2D individuals was associated with an 29% increase of all fracture risk, compared with T2D individuals who had adequate glycemic control (HR: 1.29; 95% CI, 1.22-1.36). Treatment with metformin (HR: 0.88; 95% CI, 0.85-0.92) and DPP4 inhibitors (HR: 0.93; 95% CI, 0.88-0.98) was associated with a reduced all fracture risk, while insulin (HR: 1.26; 95% CI, 1.21-1.32), thiazolidinediones (HR: 1.23; 95% CI, 1.18-1.29), and meglitinides (HR: 1.12; 95% CI, 1.00-1.26) were associated with an increased all fracture risk (All P value < 0.05). Bisphosphonates were associated similarly with increased fracture risk in the T2D and nondiabetic groups. Conclusion Longitudinal 2-year HbA1c is independently associated with elevated all fracture risk in T2D individuals during a 2-year follow-up period. Metformin and DPP4 inhibitors can be used for management of T2D fracture risk.

Introduction People with type 2 diabetes (T2D) have an increased rate of hospitalization and mortality related to COVID-19. To identify ahead of time those who are at risk of developing severe diseases and potentially in need of intensive care, we investigated the independent associations between longitudinal glycated hemoglobin (HbA1c), the impact of common medications (metformin, insulin, ACE inhibitors (ACEIs), angiotensin receptor blockers (ARBs), and corticosteroids) and COVID-19 severity in people with T2D. Research design and methods Retrospective cohort study was conducted using deidentified claims and electronic health record data from the OptumLabs Data Warehouse across the USA between January 2017 and November 2020, including 16 504 individuals with T2D and COVID-19. A univariate model and a multivariate model were applied to evaluate the association between 2 and 3-year HbA1c average, medication use between COVID-19 diagnosis and intensive care unit admission (if applicable), and risk of intensive care related to COVID-19. Results With covariates adjusted, the HR of longitudinal HbA1c for risk of intensive care was 1.12 (per 1% increase, pConclusions Two to three-year longitudinal glycemic level is independently associated with COVID-19-related severity in people with T2D. Here, we present a potential method to use HbA1c history, which presented a stronger association with COVID-19 severity than single-point HbA1c, to identify in advance those more at risk of intensive care due to COVID-19 in the T2D population. The combined use of metformin and insulin and the use of corticosteroids might be significant to prevent patients with T2D from becoming critically ill from COVID-19.