Association of sarcopenia and vitamin D deficiency with glucocorticoid-induced osteoporosis in Chinese patients with rheumatoid arthritis

Enhancing the Design of Nutrient Clinical Trials for Disease Prevention-A Focus on Vitamin D: A Systematic Review

OBJECTIVES

This systematic review (SR) highlights principles for nutrient clinical trials and explore the diverse physiological functions of vitamin D beyond its traditional role in the musculoskeletal system related to clinical study designs.

BACKGROUND

Thousands of published research articles have investigated the benefits of vitamin D (a nutrient example taken in this SR) beyond the musculoskeletal system, including the immune, pulmonary, and cardiovascular systems; pregnancy; autoimmune disorders; and cancer. They illustrated vitamin D's molecular mechanisms, interactions, and genomic and nongenomic actions.

METHODS

This SR was designed to identify shortcomings in clinical study designs, statistical methods, and data interpretation that led to inconsistent findings in vitamin D-related publications. SR also highlights examples and insights into avoiding study design errors in future clinical studies, including randomized controlled clinical trials (RCTs). The SR adheres to the latest PRISMA statement, guidelines, and the PICOS process.

RESULTS

Inappropriate or flawed study designs were frequent in clinical trials. Major failures discussed here include too short clinical study duration, inadequate or infrequent doses, insufficient statistical power, failure to measure baseline and achieved levels, and recruiting vitamin D-sufficient participants. These design errors have led to misleading interpretations. Thus, conclusions from such studies should not be generalized or used in guidelines, recommendations, or policymaking.

CONCLUSION

Adequately powered epidemiological studies and RCTs with sufficient vitamin D and duration in individuals with vitamin D deficiency reported favorable clinical outcomes, enriching the literature, enabling to understand its physiology and mechanisms. Proper study designs with rigorous methodologies and cautious interpretation of outcomes are crucial in advancing the nutrient field. The principles discussed apply not only to vitamin D, but also other micro-nutrients and nutraceutical research. Adhering to them enhances the credibility and reliability of clinical trials, SRs, and meta-analysis outcomes. The study emphasizes the importance of focused, hypothesis-driven, well-designed, statistically powered RCTs to explore the diverse benefits of nutrients, conducted in index nutrient deficient participants, and avoidance of study design errors. Findings from such studies should be incorporated into clinical practice, policymaking, and public health guidelines, improving the health of the nation and reducing healthcare costs.

Effect of zoledronic acid on muscle metabolism in mice with osteoporosis combined with sarcopenia

OBJECTIVE

To investigate the effects of zoledronic acid on muscle metabolism in mice with osteoporosis and sarcopenia and elucidate the possible underlying mechanism.

METHODS

Twenty-four 8-week-old male C57BL/6J mice were randomly divided into four groups: non-suspension (N-SUS), suspension (SUS), suspension + zoledronic acid (ZA), and suspension + PTH(PTH) groups. Equal doses of saline, zoledronic acid, and PTH were administered subcutaneously. After 4 weeks, the mice were sacrificed, and body weight and muscle mass (gastrocnemius and soleus) were measured, the right tibia of mice was taken for micro-CT examination, and the muscle specimens were analyzed using HE staining, ATPase staining, western blotting, and real-time PCR.

RESULTS

Compared with the N-SUS group, the bone mineral density (BMD), trabecular bone relative volume (BV/TV) and trabecular bone number (Tb.N) were significantly decreased in the SUS group (P < 0.01), the trabecular bone separation(Tb.Sp)was significantly increased (P < 0.01), which was reversed in ZA and PTH group (P < 0.01).Compared to the SUS group, the body and muscle weights of the ZA and PTH groups were significantly increased. Compared to the SUS group, the muscle structure was less damaged, the proportion of type I muscle fibers was increased, and the protein expression of β-catenin and AKT were upregulated in the ZA and PTH groups(P < 0.05). In addition, the mRNA expression levels of Wnt3a, Wnt16, Myf5, and PI3K were significantly increased (P < 0.05), where as those of Myogenic Differentiation Antigen(MyoD )and Myogenin (MyoG) were significantly decreased (P < 0.05). No significant differences were observed between the ZA and PTH groups.

CONCLUSIONS

Zoledronic acid can reduce muscle loss and damage by upregulating the mRNA expression of Wnt and PI3K and the protein expression of β-catenin and AKT.Our results provide a novel basis for the development of drugs for the treatment of osteoporosis combined with sarcopenia.

Role of Myostatin in Rheumatoid Arthritis: A Review of the Clinical Impact

Rheumatoid arthritis (RA) is a chronic inflammatory disease that affects synovial joints and that frequently involves extra-articular organs. A multiplicity of interleukins (IL) participates in the pathogenesis of RA, including IL-6, IL-1β, transforming growth factor-beta (TGF-β), and tumor necrosis factor (TNF)-α; immune cells such as monocytes, T and B lymphocytes, and macrophages; and auto-antibodies, mainly rheumatoid factor and anti-citrullinated protein antibodies (ACPAs). Skeletal muscle is also involved in RA, with many patients developing muscle wasting and sarcopenia. Several mechanisms are involved in the myopenia observed in RA, and one of them includes the effects of some interleukins and myokines on myocytes. Myostatin is a myokine member of the TGF-β superfamily; the overproduction of myostatin acts as a negative regulator of growth and differentiates the muscle fibers, limiting their number and size. Recent studies have identified abnormalities in the serum myostatin levels of RA patients, and these have been found to be associated with muscle wasting and other manifestations of severe RA. This review analyzes recent information regarding the relationship between myostatin levels and clinical manifestations of RA and the relevance of myostatin as a therapeutic target for future research.

The Association between Serum Level of Vitamin D and Inflammatory Biomarkers in Hospitalized Adult Patients: A Cross-Sectional Study Based on Real-World Data

Objective

The association between vitamin D status and inflammation remains unclear in hospitalized patients.

Materials and Methods

We performed the current study based on real-world data from two teaching hospitals. Serum level of vitamin D (assessed by 25-hydroxyvitamin D) was evaluated within 2 days after admission. All the patients were further classified into three groups: deficiency (<12 ng/mL), insufficiency (12-20 ng/mL), and adequate (≥20 ng/mL). White blood cell (WBC) count, serum level of C-reactive protein (CRP), and procalcitonin were also measured and used to evaluate inflammation. Other potential covariates were abstracted from medical records. Charlson comorbidity index (CCI) was calculated to assess the severity of disease.

Results

A total number of 35,528 hospitalized adult patients (21,171 men and 14,357 women) were included. The average age and BMI were 57.5 ± 16.2 years and 23.4 ± 3.7 kg/m2, respectively, while medium vitamin D level was 16.1 ng/mL (interquartile range: 11.4 ng/mL, 21.6 ng/mL) and median CCI was one point (interquartile range: 0 point, two points). The prevalence of deficiency and insufficiency was 28.0% and 40.5%. Multivariate linear regression model showed that serum level of vitamin D was significantly associated with WBC and CRP but not associated with procalcitonin. Each standard deviation (≈7.4 ng/mL) increase in vitamin D was associated with a decrease in WBC by 0.13 × 109/mL (95% CI: 0.2 × 109/mL, 0.06 × 109/mL) and 0.62 mg/L (95% CI: 0.88 mg/L, 0.37 mg/L) for CRP. Subgroup analysis and sensitivity analysis (excluding those whose eGFR <60 ml/min/1.73 m2, those whose daily calorie intake <1,000 kcal, and those who were recruited from Xin Hua hospital) generated similar results.

Conclusions

The deficiency and insufficiency of vitamin D in the hospitalized adult patients was very common. However, the results should be interpreted with caution for limited representation of the whole inpatients. Low level of vitamin D was associated with inflammatory biomarkers, which provide the evidences to early intervention for lower the risk of infection.