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

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.

Quercetin 3-O rutinoside prevents gastrointestinal injury through regulation of apoptosis in 7.5 Gy total body irradiated mice.

BACKGROUND: Despite the heightened threat to unforeseen nuclear/radiological exposures worldwide, no countermeasures are currently approved to prevent gastrointestinal (GI) toxicity induced by radiation in humans. PURPOSE: In this study, we aim to establish the gastroprotective role of flavonoid, Quercetin-3-O-rutinoside (Q-3-R) against 7.5 Gy total body gamma radiation dose that contributes to the hematopoietic syndrome. METHODS: Q-3-R (10 mg/kg body weight) was administered intramuscularly to C57BL/6 male mice before exposure to 7.5 Gy and monitored for morbidity and mortality. The GI protection against radiation was ascertained by histopathological and xylose absorption studies. Intestinal apoptosis, crypt proliferation and apoptotic signaling were also investigated in different treatment groups. RESULTS: We found that Q-3-R prevented the radiation-induced loss of mitochondrial membrane potential, maintained ATP levels, regulated the apoptotic pathway, and activated crypt cell proliferation in the intestine. Radiation-induced villi and crypt damage as well as mal-absorption were significantly minimized in the Q-3-R treated group. We observed 100% survival post Q-3-R administration against 33.3% lethality in 7.5 Gy (LD33.3/30) exposed C57BL/6 mice. The Q-3-R pre-treated mice that survived the 7.5 Gy dose revealed no pathological changes related to the development of fibrosis in the intestine and thickened mucosal wall till 4 months post irradiation. Complete hematopoietic recovery was observed in these surviving mice when compared to age matched control. CONCLUSION: The findings revealed that Q-3-R regulated the apoptotic process to achieve GI protection against LD33.3/30 dose (7.5 Gy) that primarily caused death due to hematopoietic failure. The recovery observed in mice survivors suggested that this molecule may also have the potential to minimize side effects on normal tissues during radiotherapy.

Quercetin-3-Rutinoside alleviates radiation-induced lung inflammation and fibrosis via regulation of NF-κB/TGF-ß1 signaling.

BACKGROUND: Radiation exposure to lungs during nuclear catastrophes or radiotherapy poses long-term side effects and can induce pulmonary injury sufficient for causing death. The strategies for preventing or reversing radiation-induced lung injuries have not been yet developed. Quercetin-3-Rutinoside (Q-3-R), a polyphenolic bioflavonoid, has shown multifaceted pharmacological applications due to its high antioxidant and anti-inflammatory properties. PURPOSE: In the current study, the potential of Q-3-R against radiation-induced lung pneumonitis/fibrosis and the possible underlying mechanism was investigated. STUDY DESIGN: To evaluate the effect of Q-3-R against lung damage, C57Bl/6 mice were administered with Q-3-R (10 mg/kg b.wt.) and irradiated with a single dose of gamma radiation (12 Gy) at thoracic region. METHODS: 16 weeks after irradiation lung damage was seen by histopathological studies and staining for collagen deposition. Expression of Nuclear factor kappa-B (NF-κB), transforming growth factor-ß1 (TGF-ß1), Smad3, intercellular adhesion molecule 1 (ICAM-1), α-smooth muscle actin protein (α-SMA), Aquaporin 5 (AQP 5), Interleukins (IL-6, IL-18, IL-1ß), tumor necrosis factor-α (TNF-α) and caspase-3 was evaluated by immunohistochemistry/western blot/Elisa. Reactive oxygen species (ROS)/ Nitric oxide (NO) scavenging potential of Q-3-R and inhibition of cell death in irradiated lungs were also assessed. RESULTS: Mice showed signs of pneumonitis and fibrotic changes in lungs following radiation treatment. A dramatic increase in inflammatory cells and cytokines contributing to lung disease pathogenesis was observed. Furthermore, expression of NF-κB, TGF-ß1, Smad3, ICAM-1, AQP5and α-SMA was found markedly up-regulated. However, pretreatment of Q-3-R significantly attenuated radiation-induced pneumonitis and fibrosis. Histological examination revealed less structural and fibrotic changes with down-regulation of AQP 5, ICAM-1, α-SMA and caspase-3 in Q-3-R pretreated irradiated groups. The formulation significantly relieved lung injury by suppressing inflammatory and pro-fibrotic cytokines such as IL-6, IL-18, IL-1ß, TNF-α and TGF-ß1 via inhibition of NF-κB. Q-3-R also curtailed radiation-induced ROS/NO generation and minimized DNA damage in the irradiated lungs. CONCLUSION: The findings from the current study clearly demonstrate that Q-3-R provides radioprotection to the lungs by regulating NF-κB/TGF-ß1 signaling, scavenging free radicals, preventing perivascular infiltration and prolonged inflammatory cascade which could otherwise lead to chronic radiation fibrosis. Q-3-R can be proved as a potential therapeutic agent for alleviating radiation-induced lung injury in case of planned or unplanned radiation exposure scenario.

Quercetin-3-rutinoside protects against gamma radiation inflicted hematopoietic dysfunction by regulating oxidative, inflammatory, and apoptotic mediators in mouse spleen and bone marrow.

Radiation-induced hematopoietic dysfunction is one of the most common problems during unplanned radiation exposures and also in cancer patients receiving radiotherapy. Management of the hematopoietic system is necessary to promote survival against radiation. The present study was undertaken to demonstrate the protective potential of Quercetin 3 rutinoside (Q-3-R), against gamma radiation-induced hematopoietic injuries. C57BL/6 male mice exposed either to radiation or pretreated with Q-3-R (10 mg/kg body weight) were checked for hematopoietic protection using hematotoxicity indices, histopathological, and genotoxic evaluations. To elucidate the underlying mechanisms of Q-3-R mediated hematopoietic protection, oxidative/nitrosative stress, inflammatory and apoptotic markers as well as PCNA expression in spleen cross-sections were assessed. Studies revealed Q-3-R pretreatment inhibited radiation-induced ROS in spleen cells and better maintained the total antioxidant levels in serum that were otherwise altered post 7.5 Gy exposure. The NO levels and nitrotyrosine expression were also found inhibited by Q-3-R in the spleen. Differential regulations of Bcl2, Bax and NF-κB with reduced serum TNF-α level indicated anti-apoptotic and anti-inflammatory roles of Q-3-R. Q-3-R attenuated radiation mediated spleen damage by minimizing cell death and promoting proliferation. Restoration of abnormal histopathological changes in bone marrow following Q-3-R administration correlated to reduced apoptosis and altered cell cycle distributions. Chromosomal aberrations were also found reduced in Q-3-R pretreated bone marrow. Q-3-R restored the total leukocyte counts and serum IL-6 levels, further supporting its role in promoting hematopoiesis. These findings suggest that Q-3-R can potentially be used to minimize radiation inflicted hematopoietic toxicities during accidental as well as radiotherapy scenarios.