Immune Modulatory Effects of Vitamin D on Viral Infections.

Viral infections have been a cause of mortality for several centuries and continue to endanger the lives of many, specifically of the younger population. Vitamin D has long been recognized as a crucial element to the skeletal system in the human body. Recent evidence has indicated that vitamin D also plays an essential role in the immune response against viral infections and suggested that vitamin D deficiency increases susceptibility to viral infections as well as the risk of recurrent infections. For instance, low serum vitamin D levels were linked to increased occurrence of high burdens viral diseases such as hepatitis, influenza, Covid-19, and AIDS. As immune cells in infected patients are responsive to the ameliorative effects of vitamin D, the beneficial effects of supplementing vitamin D-deficient individuals with an infectious disease may extend beyond the impact on bone and calcium homeostasis. Even though numerous studies have highlighted the effect of vitamin D on the immune cells, vitamin D's antiviral mechanism has not been fully established. This paper reviews the recent mechanisms by which vitamin D regulates the immune system, both innate and adaptive systems, and reflects on the link between serum vitamin D levels and viral infections.

Plasmonic MXene-based nanocomposites exhibiting photothermal therapeutic effects with lower acute toxicity than pure MXene.

Purpose: Here, we fabricated two plasmonic 2D Ti3C2Tx-based nanocomposites (Au/MXene and Au/Fe3O4/MXene) with similarly high anti-cancer photothermal therapy (PTT) capabilities, but with less in vivo toxicity than a pure MXene. Methods: Au/MXene was synthesized by in situ reduction of tetrachloroauric acid using NaBH4 on Ti3C2Tx flakes. For targeted PTT, magnetic Au/Fe3O4/MXene was synthesized via a reaction between freshly prepared magnetite Fe3O4 NPs and MXene solution, followed by in situ integration of gold nanoparticles (AuNPs). Results: Morphological characterization by XRD, SEM, and TEM revealed the successful synthesis of Au/MXene and Au/Fe3O4/MXene. Both new composites exhibited a significant in vitro dose-dependent PTT effect against human breast cancer cells MCF7. Interestingly, in vivo acute toxicity assays using zebrafish embryos indicated that Au/MXene and Au/Fe3O4/MXene had less embryonic mortality (LC50 ≫ 1000 µg/mL) than pure MXene (LC50=257.46 µg/mL). Conclusion: Our new Au/MXene and Au/Fe3O4/MXene nanocomposites could be safer and more suitable than the pure MXene for biomedical applications, especially when targeted PTT is warranted.

Zebrafish larvae as a model to demonstrate secondary iron overload.

OBJECTIVES: Thalassemia is the most common genetically inherited blood disorder arising from a defect in hemoglobin production, resulting in ineffective erythropoiesis and severe hemolytic anemia. While transfusion therapy corrects the anemia, it gives rise to secondary iron overload. Current iron chelation therapy performed using deferoxamine, and the efficiency of this drug was demonstrated here using the zebrafish animal model. METHODS: Zebrafish larvae were exposed for 3 days to iron [100 µmol L-1 ferric ammonium citrate; 3-6 days post fertilization (dpf)]. Then, iron treated larvae were exposed to 100 µmol L-1 deferoxamine for 3 days (6-9 dpf). Total tissue iron concentration in the whole larvae, assessed by three different assays; inductively coupled plasma mass spectrometry, colorimetry (spectrophotometry), and microscopy using iron staining followed by imaging and quantification. RESULTS: The three assays showed that iron treatment alone resulted in a significant increase in total iron. Deferoxamine treatment of the iron-loaded zebrafish larvae showed a significant decrease in total iron concentration. CONCLUSION: This study presented a clear evidence of the effectiveness of zebrafish larvae to use as a tool to study iron overload and open the door for studying the efficiency of potential new iron chelating compounds other than commercially available ones.