Toll-like Receptor Agonist CBLB502 Protects Against Radiation-induced Intestinal Injury in Mice.

BACKGROUND/AIM: The small intestine is one of the organs most vulnerable to ionizing radiation (IR) damage. However, methods to protect against IR-induced intestinal injury are limited. CBLB502, a Toll-like receptor 5 (TLR5) agonist from Salmonella flagellin, exerts radioprotective effects on various tissues and organs. However, the molecular mechanisms by which CBLB502 protects against IR-induced intestinal injury remain unclear. Thus, this study aimed to elucidate the mechanisms underlying IR-induced intestinal injury and the protective effects of CBLB502 against this condition in mice. MATERIALS AND METHODS: Mice were administered 0.2 mg/kg CBLB502 before IR at different doses for different time points, and then the survival rate, body weight, hemogram, and histopathology of the mice were analyzed. RESULTS: CBLB502 reduced IR-induced intestinal injury. RNA-seq analysis revealed that different doses and durations of IR induced different regulatory patterns. CBLB502 protected against intestinal injury mainly after IR by reversing the expression of IR-induced genes and regulating immune processes and metabolic pathways. CONCLUSION: This study preliminarily describes the regulatory mechanism of IR-induced intestinal injury and the potential molecular protective mechanism of CBLB502, providing a basis for identifying the functional genes and molecular mechanisms that mediate protection against IR-induced injury.

Unraveling the Role of RNase L Knockout in Alleviating Immune Response Activation in Mice Bone Marrow after Irradiation.

Ionizing radiation (IR) induces severe hematopoietic injury by causing DNA and RNA damage as well as activating the immune responses, necessitating the development of effective therapeutic strategies. Ribonuclease L (RNase L) as an innate immune response pathway is triggered by exogenous and endogenous abnormal dsRNA under viral infection and dyshomeostasis, thereby activating the immune responses. Thus, we investigated the effect of RNase L on irradiation-induced bone marrow damage using RNase L knockout (RNase L-/-) mice. Phenotypic analysis revealed that RNase L knockout mitigates irradiation-induced injury in the bone marrow. Further investigation into the mechanism of RNase L by RNA-seq, qRT-PCR, and CBA analysis demonstrated that RNase L deficiency counteracts the upregulation of genes related to immune responses induced by irradiation, including cytokines and interferon-stimulated genes. Moreover, RNase L deficiency inhibits the increased levels of immunoglobulins in serum induced by irradiation. These findings indicate that RNase L plays a role in the immune response induced by irradiation in the bone marrow. This study further enhances our understanding of the biological functions of RNase L in the immune response induced by irradiation and offers a novel approach for managing irradiation-induced bone marrow injury through the regulation of RNase L activation.

Toll-like Receptor Agonist CBLB502 Protects Against Cisplatin-induced Liver and Kidney Damage in Mice.

BACKGROUND/AIM: CBLB502, a Toll-like receptor-5 agonist derived from Salmonella flagellin, exerts protective roles against irradiation and chemical drugs in mammalian tissues and stimulates tissue regeneration. This study aimed to investigate whether CBLB502 can protect against liver and kidney damage induced by the chemotherapeutic drug cisplatin (CDDP) and the underlying mechanism of the protective effect. MATERIALS AND METHODS: Mice were pretreated with CBLB502 [0.2 mg/kg, intraperitoneal (i.p.) injection] 0.5 h prior to administration of CDDP (20 mg/kg, i.p. injection), and analyses of the liver and kidney indices, blood biochemistry, and histopathology were performed. RESULTS: Pretreatment with CBLB502 alleviated CDDP-induced liver and kidney damage. RNA sequencing and bioinformatic analysis indicated that CDDP induced a similar damage-promoting gene regulation pattern in the liver and kidney. CBLB502 protected against liver and kidney damage only after CDDP treatment primarily via different pathways. However, some CBLB502-regulated genes were common between the liver and kidney, including those involved in blood coagulation, fibrinolysis, hemostasis, apoptotic regulation, NF-kappaB signaling, and response to lipopolysaccharide, suggesting a general protective effect by CBLB502. CONCLUSION: Our data provide insights into the protective mechanism of CBLB502 against CDDP-induced tissue damage in the liver and kidney and might provide a basis for future studies on functional genes and regulatory mechanisms that mediate protection against chemoradiotherapy-induced damage.

Long non­coding RNA nuclear paraspeckle assembly transcript 1 regulates ionizing radiation­induced pyroptosis via microRNA­448/gasdermin E in colorectal cancer cells.

Pyroptosis is mediated by gasdermins and serves a critical role in ionizing radiation (IR)­induced damage in normal tissues, but its role in cancer radiotherapy and underlying mechanisms remains unclear. Long non­coding (lnc) RNAs serve important roles in regulating the radiosensitivity of cancer cells. The present study aimed to investigate the mechanistic involvement of lncRNAs in IR­induced pyroptosis in human colorectal cancer HCT116 cells. LncRNA, microRNA (miR)­448 and gasdermin E (GSDME) levels were evaluated using reverse transcription­quantitative polymerase chain reaction. Protein expression and activation of gasdermins were measured using western blotting. The binding association between miR­448 and GSDME was assessed using the dual­luciferase reporter assay. Pyroptosis was examined using phase­contrast microscopy, flow cytometry, Cell Counting Kit­8 assay and lactate dehydrogenase release assay. IR dose­dependently induced GSDME­mediated pyroptosis in HCT116 cells. GSDME was identified as a downstream target of miR­448. LncRNA nuclear paraspeckle assembly transcript 1 (NEAT1) was upregulated in response to IR and enhanced GSDME expression by negatively regulating miR­448 expression. Notably, NEAT1 knockdown suppressed IR­induced pyroptosis, full­length GSDME expression and GSDME cleavage compared with that in irradiated cells. In addition, NEAT1 knockdown rescued the IR­induced decrease in cell viability in HCT116 cells. The findings of the present study indicated that lncRNA NEAT1 modulates IR­induced pyroptosis and viability in HCT116 cells via miR­448 by regulating the expression, but not activation of GSDME. The present study provides crucial mechanistic insight into the potential role of lncRNA NEAT1 in IR­induced pyroptosis.