Methotrexate Chemotherapy Causes Growth Impairments, Vitamin D Deficiency, Bone Loss, and Altered Intestinal Metabolism-Effects of Calcitriol Supplementation

The Role of Intestinal Cytochrome P450s in Vitamin D Metabolism

Vitamin D hydroxylation in the liver/kidney results in conversion to its physiologically active form of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. 1,25(OH)2D3 controls gene expression through the nuclear vitamin D receptor (VDR) mainly expressed in intestinal epithelial cells. Cytochrome P450 (CYP) 24A1 is a catabolic enzyme expressed in the kidneys. Interestingly, a recently identified mutation in another CYP enzyme, CYP3A4 (gain-of-function), caused type III vitamin D-dependent rickets. CYP3A are also expressed in the intestine, but their hydroxylation activities towards vitamin D substrates are unknown. We evaluated CYP3A or CYP24A1 activities on vitamin D action in cultured cells. In addition, we examined the expression level and regulation of CYP enzymes in intestines from mice. The expression of CYP3A or CYP24A1 significantly reduced 1,25(OH)2D3-VDRE activity. Moreover, in mice, Cyp24a1 mRNA was significantly induced by 1,25(OH)2D3 in the intestine, but a mature form (approximately 55 kDa protein) was also expressed in mitochondria and induced by 1,25(OH)2D3, and this mitochondrial enzyme appears to hydroxylate 25OHD3 to 24,25(OH)2D3. Thus, CYP3A or CYP24A1 could locally attenuate 25OHD3 or 1,25(OH)2D3 action, and we suggest the small intestine is both a vitamin D target tissue, as well as a newly recognized vitamin D-metabolizing tissue.

Synergistic Brilliance: Engineered Bacteria and Nanomedicine Unite in Cancer Therapy

Engineered bacteria are widely used in cancer treatment because live facultative/obligate anaerobes can selectively proliferate at tumor sites and reach hypoxic regions, thereby causing nutritional competition, enhancing immune responses, and producing anticancer microbial agents in situ to suppress tumor growth. Despite the unique advantages of bacteria-based cancer biotherapy, the insufficient treatment efficiency limits its application in the complete ablation of malignant tumors. The combination of nanomedicine and engineered bacteria has attracted increasing attention owing to their striking synergistic effects in cancer treatment. Engineered bacteria that function as natural vehicles can effectively deliver nanomedicines to tumor sites. Moreover, bacteria provide an opportunity to enhance nanomedicines by modulating the TME and producing substrates to support nanomedicine-mediated anticancer reactions. Nanomedicine exhibits excellent optical, magnetic, acoustic, and catalytic properties, and plays an important role in promoting bacteria-mediated biotherapies. The synergistic anticancer effects of engineered bacteria and nanomedicines in cancer therapy are comprehensively summarized in this review. Attention is paid not only to the fabrication of nanobiohybrid composites, but also to the interpromotion mechanism between engineered bacteria and nanomedicine in cancer therapy. Additionally, recent advances in engineered bacteria-synergized multimodal cancer therapies are highlighted.

Seasonal and Treatment-Related Variation in 25-Hydroxy Vitamin D Concentration in Patients with Rheumatoid Arthritis

Background/Objectives: 25-hydroxy vitamin D (25-OH-D) is a fat-soluble compound that plays many essential functions, including bone formation, neuromuscular functions, and prevention of osteoporosis and inflammation. Recent data indicate that its metabolites are associated with rheumatoid arthritis (RA) progression and neuropathic pain in RA patients. We aimed to assess the effect of RA pharmacotherapy and seasonal variation on serum levels of 25-OH-D in RA patients who received treatment with methotrexate (MTX) or leflunomide (LEF) for at least one year. Methods: This study is a retrospective analysis of data collected from 101 patients with RA who received treatment for at least one year. All of them have supplemented 25-OH-D (2000 IU daily) for at least one year. Results: We observed a significant seasonal variation in 25-OH-D concentration (p = 0.004). Moreover, there were significant differences (p = 0.03) between LEF (50.63 ± 17.73 ng/mL) and MTX (34.73 ± 14.04 ng/mL) treatment groups, but only for the summer population. A correlation was observed between 25-OH-D and RA duration-once again, in the summer population (the whole group-r = -0.64; treatment subgroups-r = -0.82 for LEF and -0.61 for MTX). Deficiency of 25-OH-D (below 20 ng/mL) was confirmed in 28.7% of patients, while 18.8% had suboptimal 25-OH-D levels (20-30 ng/mL). Conclusions: Our results showed that both RA pharmacotherapy and seasonal variation affect the serum levels of 25-OH-D in patients with active RA.