Mitigative and anti-inflammatory effects of Trichostatin A against radiation-induced gastrointestinal toxicity and gut microbiota alteration in mice

Abstract

Purpose

Radiation-induced gastrointestinal injury (RIGI) is a serious side effect of abdominal and pelvic radiotherapy, which often limits the treatment of gastrointestinal and gynaecological cancers. RIGI is also observed during accidental radiological or nuclear scenarios with no approved agents available till date to prevent or mitigate RIGI in humans. Trichostatin A (TSA), an epigenetic modulator, has been currently in clinical trials for cancer treatment and is also well known for its antibiotic and antifungal properties.

Methods

In this study, partial body (abdominal) irradiation mice model was used to investigate the mitigative effect of TSA against gastrointestinal toxicity caused by gamma radiation. Mice were checked for alterations in mean body weight, diarrheal incidence, disease activity index and survival against 15 Gy radiation. Structural abnormalities in intestine and changes in microbiota composition were studied by histopathology and 16S rRNA sequencing of fecal samples respectively. Immunoblotting and biochemical assays were performed to check protein nitrosylation, expression of inflammatory mediators, infiltration of inflammatory cells and changes in pro-inflammatory cytokine.

Results

TSA administration to C57Bl/6 mice improved radiation induced mean body weight loss, maintained better health score, reduced disease activity index and promoted survival. The 16S rRNA sequencing of fecal DNA demonstrated that TSA influenced the fecal microbiota dynamics with significant alterations in the Firmicutes/Bacteriodetes ratio. TSA effectively mitigated intestinal injury, down-regulated NF-κB, Cox-2, iNOS expression, inhibited PGE2 and protein nitrosylation levels in irradiated intestine. The upregulation of NLRP3-inflammasome complex and infiltrations of inflammatory cells in the inflamed intestine were also prevented by TSA. Subsequently, the myeloperoxidase activity in intestine alongwith serum IL-18 levels was found reduced.

Conclusion

These findings provide evidence that TSA inhibits inflammatory mediators, alleviates gut dysbiosis, and promotes structural restoration of the irradiated intestine. TSA, therefore, can be considered as a potential agent for mitigation of RIGI in humans.

Graphical Abstract

Depicting the possible mechanism of action of TSA against radiation induced gastrointestinal injury in mice. Radiation leads to activation of NF-κB, the master regulator of inflammation and it target proteins Cox-2 and iNOS. Activation of these key inflammatory mediators further up-regulated NLRP3/inflammosome complex, NO-mediated protein modifications and infiltration of inflammatory cells in the irradiated intestine. Further alterations in diversity and composition of gut microbiota contributed to inflammation and GI injury in presence of radiation. TSA administration post irradiation maintained intestinal integrity, and reduced inflammation. Restoration of gut microbiota dynamics and reduced inflammation by TSA might have mitigated radiation mediated gastrointestinal injury and have contributed to survival against irradiation.

Keywords:

• Trichostatin A
• gastrointestinal injury
• gut dysbiosis
• inflammation
• ionizing radiation
• radiomitigator

Acknowledgments

We acknowledge DRDO for funding the project (TD-15/INM313) and Director, INMAS for administrative support. The supports from officer in charge, irradiation, animal experimentation and hematology facilities are duly acknowledged. A Dahiya acknowledge DRDO for senior research fellowship.

Disclosure statement

The authors declare no conflict of interest in the study. All authors contributed to the article and approved the submitted version.

Data availability statement

The original contributions presented in the study are included in the article and as supplementary material. Further inquiries can be directed to the corresponding author.

Additional information

Funding

The entire study was carried out in project TD-15/INM313/2.0 funded by Defence Research and Development Organization (DRDO), Ministry of Defence, Govt. of India.

Notes on contributors

Akshu Dahiya

Akshu Dahiya, MSc, is a research scholar working at Institute of Nuclear Medicine and Allied Sciences (INMAS), Defence Research and Development Organization (DRDO), Ministry of Defence, Delhi, India.

Paban K. Agrawala

Paban K. Agrawala, PhD is Scientist ‘F’ at Institute of Nuclear Medicine and Allied Sciences (INMAS), Defence Research and Development Organization (DRDO), Ministry of Defence, Delhi, India with specialization in development of countermeasure agents against radiation injuries.

Ajaswrata Dutta

Ajaswrata Dutta, PhD is Scientist ‘F’ at Institute of Nuclear Medicine and Allied Sciences (INMAS), Defence Research and Development Organization (DRDO), Ministry of Defence, Delhi, India. with skills on development of animal models for radiation syndromes and countermeasure agents against GI injury.