Use of recombinant Lactobacillus sakei for the prevention and treatment of radiation-induced enteritis

Review of compounds that exhibit radioprotective and/or mitigatory effects after application of diagnostic or therapeutic ionizing radiation

PURPOSE

Exposure to ionizing radiation can be accidental or for medical purposes. Analyzes of the frequency of radiation damage in the general population, it has been determined that by far the most common are those that occur as a result of diagnostic or therapeutic procedures. Damage caused by radiation, either accidentally or for therapeutic purposes, can be reduced by the use of radioprotectors, mitigators or other therapeutic agents. A detailed research of the available literature shows that there is little systematized data of potentially radioprotective and/or mitigating effects of drugs from the personal therapy of patients during the application of therapeutic ionizing radiation. The aim of this paper is to present review of compounds, especially personal therapy drugs, that exhibit radioprotective and/or mitigating effects after the application of diagnostic or therapeutic ionizing radiation.

CONCLUSIONS

Given the widespread use of ionizing radiation for diagnostic and therapeutic purposes, there is a clear need to create a strategy and recommendations of relevant institutions for the use of radioprotectors and mitigators in everyday clinical practice, with individual evaluation of the patient's condition and selection of the compounds that will show the greatest benefit in terms of radioprotection.

Evaluation of Bacteria and Fungi DNA Abundance in Human Tissues

Whereas targeted and shotgun sequencing approaches are both powerful in allowing the study of tissue-associated microbiota, the human: microorganism abundance ratios in tissues of interest will ultimately determine the most suitable sequencing approach. In addition, it is possible that the knowledge of the relative abundance of bacteria and fungi during a treatment course or in pathological conditions can be relevant in many medical conditions. Here, we present a qPCR-targeted approach to determine the absolute and relative amounts of bacteria and fungi and demonstrate their relative DNA abundance in nine different human tissue types for a total of 87 samples. In these tissues, fungi genomes are more abundant in stool and skin samples but have much lower levels in other tissues. Bacteria genomes prevail in stool, skin, oral swabs, saliva, and gastric fluids. These findings were confirmed by shotgun sequencing for stool and gastric fluids. This approach may contribute to a more comprehensive view of the human microbiota in targeted studies for assessing the abundance levels of microorganisms during disease treatment/progression and to indicate the most informative methods for studying microbial composition (shotgun versus targeted sequencing) for various samples types.

Regulation of the regeneration of intestinal stem cells after irradiation

Background

Radiation enteritis is common in cancer patients with abdominal and pelvic malignant tumors that have received radiotherapy. Regeneration of intestinal stem cells is a critical process for intestine self-repairing post-irradiation. In this study, we attempted to find out the molecules that promote the regeneration of intestinal stem cells to repair the irradiation damage.

Methods

Male C57BL/6 mice were given a single dose of 12 Gy irradiation, and in vitro cultured organoids were given 6 Gy X-rays to construct the regeneration of intestinal stem cells. Hematoxylin and eosin (H&E) staining was performed for morphological observation. In situ hybridization was used to detect the expression of Lgr5, and immunofluorescence staining was adopted to detect the expression of CD44. FACS was used to sort CD44 positive cells of crypts. RNA was then extracted, and RNA-Seq was performed. The Wnt11 over-expression cell line was constructed to collect the Wnt11 conditioned medium (CM).

Results

The results showed both Lgr5 and CD44 located at the bottom of normal crypts. The expression of Lgr5 was lower at day 3.5, 5, but recovered at day 10 post-irradiation compared with the control. However, the expression of CD44 was higher at day 3.5, 5, but recovered at day 10 post-irradiation compared with the control group. The quantitative real-time polymerase chain reaction (qRT-PCR) assay showed consistent results. RNA-Seq results showed that Wnt11 was over-expressed in the irradiation group. After irradiation adding Wnt11 condition medium to culture, the intestinal organoids resulted in a bigger size and more buddings of the newborn organoids compared with the control group.

Conclusions

The expression of CD44 increases during the radiation-induced regeneration of intestinal stem cells while Lgr5 decreases, adding Wnt11 CM can facilitate the proliferation of the newborn organoids after irradiation. Wnt11 is a potential target to promote the regeneration of intestinal stem cells to repair the radiation injury.

Vitamin D, gut microbiota, and radiation-related resistance: a love-hate triangle

Radiation resistance is a serious issue in radiotherapy. Increasing evidence indicates that the human gut microbiome plays a role in the development of radiation resistance. Vitamin D is an important supplement for cancer patients treated with radiotherapy. Against this background, this paper reviewed research regarding the associations among vitamin D, microbiota dysbiosis, and radiation resistance. A hypothesis is developed to describe the relationships among vitamin D, the gut microbiota, and radiotherapy outcomes. Radiotherapy changes the composition of the gut microbiota, which in turn influence the serum level of vitamin D, and its distribution and metabolism in the body. Alteration of vitamin D level influences the patient response to radiotherapy, where the underlying mechanisms may be associated with the intestinal microenvironment, immune molecules in the intestines, gut microbiome metabolites, and signaling pathways associated with vitamin D receptors. Our understanding of the contribution of vitamin D and the gut microbiota to radiotherapy outcomes has been increasing gradually. A better understanding of the relationships among vitamin D, the gut microbiota, and radiotherapy outcomes will shed more light on radiation resistance, and also promote the development of new strategies for overcoming it, thus addressing an important challenge associated with the currently available radiotherapy modalities for cancer patients.

Protective effects of zingerone derivate on ionizing radiation-induced intestinal injury

Intestinal injury is the primary toxicity of radiotherapy for pelvic and abdominal tumors, and it is also one of the common acute complications of radiotherapy. At present, there are no effective drugs to prevent intestinal injury in the clinic. Zingerone is a natural product with radioprotective effects. In this study, a novel compound (thiazolidine hydrochloride, TZC01) was synthesized by structural modification of zingerone. The effects of TZC01 on preventing intestinal injury from radiation were further investigated in this study. C57BL/6N mice were exposed to a lethal dose of abdominal irradiation (ABI) with and without TZC01 treatments. The morphological changes of the intestine and various makers of intestinal crypt cells were investigated. Treatment with TZC01 improved the survival rate of mice exposed to 12 Gy ABI. Moreover, TZC01 protected the intestinal morphology of mice, decreased the apoptotic rate of intestinal crypt cells, maintained cell regeneration and promoted crypt cell proliferation and differentiation. This study suggests that TZC01 has preventive and therapeutic effects on radiation enteritis by promoting the proliferation and differentiation of crypt cells to protect the small intestine from the toxic effects of ionizing radiation. Furthermore, the study of TCZ01 lays a strong foundation for developing novel radioprotectors with multiple properties.

Therapeutic bacteria to combat cancer; current advances, challenges, and opportunities

Successful treatment of cancer remains a challenge, due to the unique pathophysiology of solid tumors, and the predictable emergence of resistance. Traditional methods for cancer therapy including radiotherapy, chemotherapy, and immunotherapy all have their own limitations. A novel approach is bacteriotherapy, either used alone, or in combination with conventional methods, has shown a positive effect on regression of tumors and inhibition of metastasis. Bacteria-assisted tumor-targeted therapy used as therapeutic/gene/drug delivery vehicles has great promise in the treatment of tumors. The use of bacteria only, or in combination with conventional methods was found to be effective in some experimental models of cancer (tumor regression and increased survival rate). In this article, we reviewed the major advantages, challenges, and prospective directions for combinations of bacteria with conventional methods for tumor therapy.