An elemental diet protects mouse salivary glands from 5‑fluorouracil‑induced atrophy

The Protective Effects of MSC-Derived Exosomes Against Chemotherapy-Induced Parotid Gland Cytotoxicity

Background: Fluorouracil (5-FU) is one of the most popular chemotherapeutic agents used in various cancer therapy protocols. Cell-free therapy utilizing exosomes is gaining increased popularity as a safer option due to concerns over potential tumor progression following stem cell therapy. Methods: Parotid glands of albino were treated with a single bone marrow mesenchymal stem cell (BMMSC)-derived exosomes injection (100 μg/kg/dose suspended in 0.2 mL phosphate-buffered saline [PBS]), a single 5-Fu injection (20 mg/kg), and BMMSC-derived exosomes plus 5-FU and compared to control group (daily saline injections). After 30 days, the parotid glands were examined using qualitative histological evaluation, immunohistochemical evaluation using rabbit polyclonal mouse antibody to Ki-67, caspase 3, and iNOS, as well as quantitative real-time polymerase chain reaction (RT-PCR) to evaluate gene expression of TGFβ1, TNF-α, and BCL-2. Results: Histological examination of the parotid gland revealed that BMMSC-derived exosomes restored the glands' architecture and repaired most of the distortion created by 5-FU. Immunohistochemical expression of tumor proliferation and cell death markers were restored to normal levels in the exosome-treated groups that were similar to the control group. Furthermore, BMMSC-derived exosomes reversed the effects of 5-FU on quantitative gene expression levels and showed a significant decrease in TNF-α (p < 0.001) and a significant increase in TGFβ (p < 0.0001) and BCL-2 (p < 0.05) when compared to 5-FU treatment. Conclusion: Within the limitations of the current study, BMMSC-derived exosomes have the potential to counteract the cytotoxic effects of 5-FU on the parotid glands of rats in vivo. Further studies are deemed necessary to simulate clinical scenarios.

5-FU Weakens Defensive Functions of the Junctional Epithelium

AIM

To investigate additional factors contributing to the pathophysiology of chemotherapy-induced oral mucositis and periodontitis beyond the systemic immune suppression caused by the chemotherapeutic agent 5-Fluorouracil (5-FU).

METHODS

5-Fluorouracil was topically delivered to the non-keratinized, rapidly proliferating junctional epithelium (JE) surrounding the dentition, and acts as an immunologic and functional barrier to bacterial ingression. Various techniques, including EdU incorporation, quantitative immunohistochemistry (qIHC), histology, enzymatic activity assays, and micro-computed tomographic (μCT) imaging, were employed to analyze the JE at multiple time points following topical 5-FU treatment. Systemic 5-FU delivery was used for comparison, and all 5-FU treated tissues were compared to vehicle-treated controls.

RESULTS

We first showed that systemic 5-FU blocked mitotic activity that rapidly led to JE atrophy. This atrophy was accompanied by suppression of the immune system. We then demonstrated that topical 5-FU delivery effectively inhibited cell proliferation in the JE. Quantitative immunohistochemical (qIHC) analyses further demonstrated a progressive breakdown in JE barrier functions following topical 5-FU. CBC analyses confirmed that topical 5-FU did not alter the innate immune system but did suppress the local immune response of the JE. The longer-term consequences of this disruption in JE barrier functions were significant alveolar bone loss and an increase in porosity. Together, these results document the essential requirement for rapid JE cell proliferation to maintain homeostasis of the periodontium.

CONCLUSIONS

The reduction of cell division in the JE due to 5-FU treatment directly compromises both its structural integrity and immune surveillance capabilities, contributing to the destruction of periodontal hard tissues.

Nonpharmacological approaches for improving gut resilience to chemotherapy

PURPOSE OF REVIEW

Mucositis of the gastrointestinal tract is a debilitating side effect of chemotherapy that negatively influences treatment tolerance and patient life quality. This review will evaluate the recent literature on nonpharmacological strategies that have the potential to improve chemotherapy-induced mucositis (CIM).

RECENT FINDINGS

Alternatives to pharmacological approaches have shown great promise in preventing CIM. Natural products, including curcumin, ginseng, quercetin, and patchouli all show potential in mitigating CIM. In addition, dietary patterns, such as the elemental diet, high fiber diet, and diets high in amino acids have documented benefits in preventing CIM. Perhaps the greatest advancement coming to this arena in recent years is in the field of probiotics. Indeed, research on single species as well as probiotic mixtures show potential in reducing CIM insofar as probiotics are now being suggested for treatment of CIM by governing bodies. Although behavioral interventions including psychological interventions and exercise interventions have shown promise in reducing cancer therapy-related side effects, more work in this domain is warranted and particularly in the context of CIM.

SUMMARY

Alternatives to pharmacological approaches show great potential for use in prevention and treatment of CIM and should be further developed for use in the clinic.