Mesenchymal stromal cells can repair radiation-induced pulmonary fibrosis via a DKK-1-mediated Wnt/ß-catenin pathway.

Pulmonary injury occurring after thoracic radiotherapy is a main factor limiting the curative effect of radiotherapy. Robust activation of the Wnt signalling pathway induced by ionizing radiation stress plays a critical role in epithelial-mesenchymal transition (EMT) in irradiated type II alveolar epithelial cells and in the proliferation of pulmonary fibroblasts, which contributes to the formation of fibrotic lesions in irradiated lungs. The pathogenesis of radiation-induced pulmonary fibrosis could be restricted by systemic delivery of human adipose-derived mesenchymal stromal cells (Ad-MSCs), as evidenced by the inhibitory effects of Ad-MSCs on EMT in irradiated type II alveolar epithelial cells. The purpose of this study is to observe the effects of mesenchymal stromal cells (MSCs) on repairing fibrosis caused by radiation. We used western blotting and real-time PCR to observe the expression of DKK-1 in MSCs of different origins and passages. After the successful establishment of a radiation-induced lung injury model, we investigated the potency of the supernatant from stromal cells to reduce pro-fibrotic events, including EMT and fibroblast activation. To study the mechanism, we evaluated the levels of active ß-catenin, TCF4 and the target genes Snail, Twist and c-Myc. After the injection of Ad-MSCs into mice via the tail vein, proteins related to EMT, fibroblasts and Wnt/ß-catenin signalling were investigated. The TGF-ß and IL-10 protein concentrations in peripheral blood were measured by ELISA. Ad-MSC-derived supernatant effectively reversed the decrease in E-cadherin expression and inhibited the increase in vimentin expression induced by ionizing radiation in epithelial cells and suppressed the expression of α-SMA, a mediator of fibroblast proliferation. The canonical Wnt pathway may be activated by irradiation but the nuclear localization of active ß-catenin was reduced in the presence of the supernatant from Ad-MSCs. In addition, the expression of target genes involved in EMT was downregulated. Additionally, when DKK-1 in the supernatant was neutralized, all these effects were reversed. Changes in the levels of proteins related to EMT and fibroblast activation, as well as those of active ß-catenin and TCF4, were similar in vivo and in vitro. The serum level of the immunosuppressive factor IL-10 was increased after radiation and was further enhanced after Ad-MSC interference for one month. In conclusion, Ad-MSCs medium can contain DKK-1 and inhibit the induction of EMT via Wnt/ß-catenin signalling in vitro and in vivo.

Salt-inducible Kinase (SIK1) regulates HCC progression and WNT/ß-catenin activation.

BACKGROUND & AIMS: In this study, we investigated the role of salt-inducible kinase 1 (SIK1) and its possible mechanisms in human hepatocellular carcinoma (HCC). METHODS: Immunoprecipitation, immunohistochemistry, luciferase reporter, Chromatin immunoprecipitation, in vitro kinase assays and a mouse model were used to examine the role of SIK1 on the ß-catenin signaling pathway. RESULTS: SIK1 was significantly downregulated in HCC compared with normal controls. Its introduction in HCC cells markedly suppresses epithelial-to-mesenchymal transition (EMT), tumor growth and lung metastasis in xenograft tumor models. The effect of SIK1 on tumor development occurs at least partially through regulation of ß-catenin, as evidenced by the fact that SIK1 overexpression leads to repression of ß-catenin transcriptional activity, while SIK1 depletion has the opposite effect. Mechanistically, SIK1 phosphorylates the silencing mediator of retinoic acid and thyroid hormone receptor (SMRT) at threonine (T)1391, which promotes the association of nuclear receptor corepressor (NCoR)/SMRT with transducin-beta-like protein 1 (TBL1)/transducing-beta-like 1 X-linked receptor 1 (TBLR1) and disrupts the binding of ß-catenin to the TBL1/TBLR1 complex, thereby inactivating the Wnt/ß-catenin pathway. However, SMRT-T1391A reverses the phenotype of SIK1 and promotes ß-catenin transactivation. Twist1 is identified as a critical factor downstream of SIK1/ß-catenin axis, and Twist1 knockdown (Twist1(KD)) reverses SIK1(KD)-mediated changes, whereas SIK1(KD)/Twist1(KD) double knockdown cells were less efficient in establishing tumor growth and metastasis than SIK1(KD) cells. The promoter activity of SIK1 were negatively regulated by Twist1, indicating that a double-negative feedback loop exists. Importantly, levels of SIK1 inversely correlate with Twist1 expression in human HCC specimens. CONCLUSIONS: Our findings highlight the critical roles of SIK1 and its targets in the regulation of HCC development and provides potential new candidates for HCC therapy.

Mensenchymal stem cells can delay radiation-induced crypt death: impact on intestinal CD44(+) fragments.

Intestinal stem cells are primitive cells found within the intestinal epithelium that play a central role in maintaining epithelial homeostasis through self-renewal and commitment into functional epithelial cells. Several markers are available to identify intestinal stem cells, such as Lgr5, CD24 and EphB2, which can be used to sort intestinal stem cells from mammalian gut. Here, we identify and isolate intestinal stem cells from C57BL/6 mice by using a cell surface antigen, CD44. In vitro, some CD44(+) crypt cells are capable of forming "villus-crypt"-like structures (organoids). A subset strongly positive for CD44 expresses high levels of intestinal stem-cell-related genes, including Lgr5, Bmi1, Hopx, Lrig1, Ascl2, Smoc2 and Rnf43. Cells from this subset are more capable of developing into organoids in vitro, compared with the subset weakly positive for CD44. However, the organoids are sensitive to ionizing irradiation. We investigate the specific roles of mesenchymal stem cells in protecting organoids against radiation-induced crypt death. When co-cultured with mesenchymal stem cells, the crypt domains of irradiated organoids possess more proliferative cells and fewer apoptotic cells than those not co-cultured with mesenchymal stem cells. Cd44v6 continues to be expressed in the crypt domains of irradiated organoids co-cultured with mesenchymal stem cells. Our results indicate specific roles of mesenchymal stem cells in delaying radiation-induced crypt death in vitro.

Intravenous delivery of adipose-derived mesenchymal stromal cells attenuates acute radiation-induced lung injury in rats.

BACKGROUND AIMS: Radiation-induced lung injury (RILI) commonly occurs in patients with thoracic cancer. However, an effective treatment option has not yet been established. Adipose-derived mesenchymal stromal cells (Ad-MSCs) have significant potential for clinical use, but their role in RILI is currently unknown. We aimed to evaluate the therapeutic capacity of Ad-MSCs to heal acute RILI in rats. METHODS: Sprague-Dawley rats were used in this study. Rat Ad-MSCs were delivered through the tail veins of rats 2 h after thorax irradiation. Lung histopathologic findings, pulmonary levels of inflammatory cytokines (interleukin [IL]-1, IL-6, IL-10 and tumor necrosis factor-α), pro-fibrotic factors (transforming growth factor [TGF]-ß1, connective tissue growth factor, α-smooth muscle actin and type 1 collagen), pro- or anti-apoptotic mediators (Bcl-2, Bax and caspase-3) and the multifunctional factor hepatocyte growth factor were evaluated after Ad-MSC transplant. RESULTS: Intravenous delivery of Ad-MSCs attenuated acute RILI. Further studies showed that Ad-MSCs had anti-inflammation and anti-fibrotic effects and maintained lung epithelium integrity, as indicated by reduced serum levels of the pro-inflammatory cytokines IL-1, IL-6 and tumor necrosis factor-α, increased levels of the anti-inflammatory cytokine IL-10, and downregulated transforming growth factor -ß1, α-smooth muscle actin and type 1 collagen levels in irradiated lung tissues. Ad-MSCs also regulated the expression of pro- and anti-apoptotic mediators (Bcl-2, Bax and caspase-3) to protect lung cells from apoptosis. CONCLUSIONS: Intravenous Ad-MSC delivery attenuated acute RILI through anti-inflammation, anti-fibrosis and anti-apoptosis mechanisms.

Intramyocardial injection of hypoxia-preconditioned adipose-derived stromal cells treats acute myocardial infarction: an in vivo study in swine.

Hypoxic preconditioning is a promising method for improving the anti-apoptotic and paracrine signaling capabilities of adipose-derived stromal cells (ADSCs). The purpose of this study was to analyze the influence of different hypoxic conditions on ADSCs and the therapeutic effects of hypoxia-preconditioned ADSCs (HPADSCs) on an animal model of myocardial infarction (MI). For the in vitro studies, ADSCs were divided into five groups and cultured in different oxygen concentrations (1, 3, 5, 10, and 21 %). After 24 h, RT-PCR and western blots showed that 3 % oxygen preconditioning could improve the viability and cytokine secretion of the ADSCs. A Matrigel assay indicated that the HPADSC-conditioned medium could stimulate endothelial cells to form capillary-like tubes. For the in vivo studies, MI was induced by coronary occlusion in 24 mature Chinese minipigs. The animals were divided into three groups and treated by intramyocardial injection with vehicle alone (saline group), with 1 × 10(8) ADSCs cultured in normoxic conditions (ADSCs group) or with 1 × 10(8) ADSCs precultured in 3 % oxygen (HPADSCs group). SPECT and echocardiography demonstrated that cardiac function was improved significantly in the HPADSC transplant group compared with the vehicle control group (P < 0.05). Immunofluorescence showed fewer apoptotic cells and more small- to medium-sized vessels in the HPADSC transplantation group (P < 0.05). Three percent oxygen is the optimum preconditioning treatment for ADSCs. HPADSC transplantation can prevent ventricular remodeling and reduce the infarct size.

Radiation enteropathy-related depression: A neglectable course of disease by gut bacterial dysbiosis.

Radiation enteropathy (RE) is common in patients treated with radiotherapy for pelvic-abdominal cancers. Accumulating data indicate that gut commensal bacteria determine intestinal radiosensitivity. Radiotherapy can result in gut bacterial dysbiosis. Gut bacterial dysbiosis contributes to the pathogenesis of RE. Mild to moderate depressive symptoms can be observed in patients with RE in clinical settings; however, the rate of these symptoms has not been reported. Studies have demonstrated that gut bacterial dysbiosis induces depression. In the state of comorbidity, RE and depression may be understood as local and abscopal manifestations of gut bacterial disorders. The ability of comorbid depression to worsen inflammatory bowel disease (IBD) has long been demonstrated and is associated with dysfunction of cholinergic neural anti-inflammatory pathways. There is a lack of direct evidence for RE comorbid with depression. It is widely accepted that RE shares similar pathophysiologic mechanisms with IBD. Therefore, we may be able to draw on the findings of the relationship between IBD and depression. This review will explore the relationship between gut bacteria, RE, and depression in light of the available evidence and indicate a method for investigating the mechanisms of RE combined with depression. We will also describe new developments in the treatment of RE with probiotics, prebiotics, and fecal microbial transplantation.

Postoperative therapy for local-advanced gastric cancer: A systematic review and meta-analysis.

BACKGROUND: Adjuvant therapy after surgery is effective for the treatment of advanced gastric cancer (GC), but the regimens are not uniform, resulting in imbalanced benefits. OBJECTIVES: To compare the overall survival (OS), relapse-free survival (RFS) and disease-free survival (DFS) of patients with local-advanced GC (LAGC) after surgery plus adjuvant therapy and with surgery alone based on meta-analysis. MATERIAL AND METHODS: Literature search was performed among the articles published in the PubMed, Embase and Cochrane Library databases from January 2000 to December 2018. Study selection was conducted based on the following criteria: randomized clinical trials (RCTs) on surgery plus adjuvant therapy compared to surgery alone; studies compared OS and/or RFS/DFS; and cases medically confirmed with LAGC. Only articles in English were included. RESULTS: A total of 12 datasets from 11 randomized controlled trials (RCTs) involving 4606 patients were included in the meta-analysis. There was a significant improvement in OS of patients who underwent postoperative adjuvant therapy (HR 0.78; 95% CI: 0.72-0.84; p < 0.001). In the subgroup analysis, it showed a higher improvement in OS patients who received adjuvant chemotherapy plus immunotherapy or radiotherapy (HR 0.72; 95% CI: 0.61-0.85; p < 0.001). CONCLUSION: Adjuvant therapy led to survival benefits in patients with LAGC.

Efficacy and safety of immune checkpoint inhibitors with or without radiotherapy in metastatic non-small cell lung cancer: A systematic review and meta-analysis.

Background and purpose: Although immune checkpoint inhibitors (ICIs) have become the first-line treatment for metastatic non-small cell lung cancer (mNSCLC), their efficacy is limited. Meanwhile, recent reports suggest that radiotherapy (RT) can activate the systemic antitumor immune response by increasing the release of antigens from tumor tissues. Therefore, in patients with mNSCLC treated with ICIs, investigations were performed to determine whether the addition of RT improved the outcomes. Furthermore, the adverse events rate was evaluated. Methods and materials: Pubmed, Embase, and Cochrane Library were searched using the keywords "radiotherapy," "immune checkpoint inhibitors," and "non-small cell lung cancer" from the date of inception to 2 May 2022. Randomized controlled trials (RCTs) and nonRCTs (NRCTs) comparing the efficacy and safety of RT combined with ICIs versus ICIs alone in metastatic NSCLC were assessed. The primary outcomes were progression-free survival (PFS) and overall survival (OS), and the secondary outcomes were abscopal response rate (ARR), abscopal control rate (ACR), adverse events rate, and pneumonia rate. The analyses were conducted using the Mantel-Haenszel fixed-effects or random-effects model. The I2 statistic was used to determine heterogeneity, whereas funnel plots and Egger's test were used to assess publication bias. Results: In 15 clinical studies, 713 patients received RT combined with ICIs and 1,275 patients received only ICIs. With regard to PFS and OS, the hazard ratios of RT combined with ICIs were 0.79 (0.70, 0.89) and 0.72 (0.63, 0.82), respectively. In terms of ARR and ACR, the odds ratios (ORs) of RT combined with ICIs were 1.94 (1.19, 3.17) and 1.79 (1.08, 2.97), respectively. Subgroup analyses based on study type (RCT/NRCT), RT target (intracranial/extracranial), number of RT sites (single site), previous ICI resistance (yes/no), and sequencing of RT and ICIs (concurrent/post-RT ICIs) revealed that the addition of RT significantly prolonged PFS and OS. However, subgroup analyses based on radiation dose/fractionation indicated that the addition of hypofractionated RT significantly prolonged OS but not PFS. When grouped according to the level of PD-L1 expression, the addition of RT prolonged PFS only in patients who were PD-L1-negative. Furthermore, subgroup analyses of ARR and ACR signified that the combination therapy resulted in better local control of lesions outside the irradiation field in the hypofractionated RT, extracranial RT, and ICI-naïve subgroups. In terms of adverse events, the addition of RT did not significantly increase the adverse events rate but was associated with a higher pneumonia rate [OR values were 1.24 (0.92, 1.67) and 1.76 (1.12, 2.77), respectively]. Conclusion: Meta-analysis of existing data suggests that the addition of RT can significantly prolong PFS and OS in patients with metastatic NSCLC receiving ICIs. In addition to lesions in the irradiation field, RT can improve the local control rate of lesions outside the irradiation field via immune activation. Combination therapy does not increase the overall risk of adverse reactions, except for pneumonia.

Comprehensive Next-Generation Sequencing Reveals Novel Predictive Biomarkers of Recurrence and Thoracic Toxicity Risks After Chemoradiation Therapy in Limited Stage Small Cell Lung Cancer.

PURPOSE: Although definitive chemoradiation therapy (dCRT) remains the most effective treatment modality in limited stage small cell lung cancer (SCLC), some patients progress quickly or develop serious radiation-induced thoracic toxicity (RITT). Molecular correlates of response to dCRT remain to be explored. METHODS AND MATERIALS: Genomic profiling was performed retrospectively on 231 patients with limited-stage SCLC treated with dCRT between 2015 and 2019 using a customized panel covering cancer and radiation therapy response-related genes. Exploratory associations of progression-free survival, overall survival, and RITT with clinical features, tumor genetics, genomic and molecular pathway alterations, and single nucleotide polymorphisms were conducted. RESULTS: In addition to the common SCLC genes, such as TP53, RB1, and NOTCH1/2, potentially actionable mutations in EGFR, KRAS, and BRCA1/2 were among the top alterations in the cohort. At the single-gene level, CDK4 and GATA6 alterations were independent predictors of poor survival by multivariate analysis. At the genomic level, high tumor mutational burden was strongly associated with favorable survival outcome. Pathway-level analysis showed that activating mutations in the MAPK/ERK pathway genes, particularly those in EGFR/ERBB2, correlated with poor survival. Combined analysis enabled optimized risk stratification of post-dCRT survival. On the other hand, our study also confirmed that single nucleotide polymorphisms in MTHFR, CYP2B6, NQO1, and LIG4 were risk alleles of high-grade RITT. Remarkably, somatic loss-of-function mutations in the DNA damage repair pathway genes were associated with increased risk of high-grade RITT, particularly pneumonitis, which likely reflect a complex interplay between the tumor and its immune microenvironment. CONCLUSIONS: Taken together, by examining the mutational landscape of a large cohort of limited-stage SCLC, we identified novel molecular predictors of survival and RITT. Our findings also implicate several key molecular pathways, including the MAPK/ERK and DNA damage repair pathways, in the regulation of dCRT response.

Genomic Profiling Reveals Novel Predictive Biomarkers for Chemo-Radiotherapy Efficacy and Thoracic Toxicity in Non-Small-Cell Lung Cancer.

Chemo-radiotherapy (CRT) remains the main treatment modality for non-small-cell lung cancer (NSCLC). However, its clinical efficacy is largely limited by individual variations in radio-sensitivity and radiotherapy-associated toxicity. There is an urgent need to identify genetic determinants that can explain patients' likelihood to develop recurrence and radiotherapy-associated toxicity following CRT. In this study, we performed comprehensive genomic profiling, using a 474-cancer- and radiotherapy-related gene panel, on pretreatment biopsy samples from patients with unresectable stage III NSCLCs who underwent definitive CRT. Patients' baseline clinical characteristics and genomic features, including tumor genetic, genomic and molecular pathway alterations, as well as single nucleotide polymorphisms (SNPs), were correlated with progression-free survival (PFS), overall survival (OS), and radiotherapy-associated pneumonitis and/or esophagitis development after CRT. A total of 122 patients were enrolled between 2014 and 2019, with 84 (69%) squamous cell carcinomas and 38 (31%) adenocarcinomas. Genetic analysis confirmed the association between the KEAP1-NRF2 pathway gene alterations and unfavorable survival outcome, and revealed alterations in FGFR family genes, MET, PTEN, and NOTCH2 as potential novel and independent risk factors of poor post-CRT survival. Combined analysis of such alterations led to improved stratification of the risk populations. In addition, patients with EGFR activating mutations or any oncogenic driver mutations exhibited improved OS. On the other hand, we also identified genetic markers in relation to radiotherapy-associated thoracic toxicity. SNPs in the DNA repair-associated XRCC5 (rs3835) and XRCC1 (rs25487) were associated with an increased risk of high-grade esophagitis and pneumonitis respectively. MTHFR (rs1801133) and NQO1 (rs1800566) were additional risk alleles related to higher susceptibility to pneumonitis and esophagitis overall. Moreover, through their roles in genome integrity and replicative fidelity, somatic alterations in ZNF217 and POLD1 might also serve as risk predictors of high-grade pneumonitis and esophagitis. Taken together, leveraging targeted next-generating sequencing, we identified a set of novel clinically applicable biomarkers that might enable prediction of survival outcomes and risk of radiotherapy-associated thoracic toxicities. Our findings highlight the value of pre-treatment genetic testing to better inform CRT outcomes and clinical actions in stage III unresectable NSCLCs.

KRAS Mutation Dictates the Cancer Immune Environment in Pancreatic Ductal Adenocarcinoma and Other Adenocarcinomas.

Generally, patients with pancreatic ductal adenocarcinoma, especially those with wide metastatic lesions, have a poor prognosis. Recently, a breakthrough in improving their survival has been achieved by using first-line chemotherapy, such as gemcitabine plus nab-paclitaxel or oxaliplatin plus irinotecan plus 5-fluorouracil plus calcium folinate. Unfortunately, regimens with high effectiveness are still absent in second- or later-line settings. In addition, although immunotherapy using checkpoint inhibitors definitively represents a novel method for metastatic cancers, monotherapy using checkpoint inhibitors is almost completely ineffective for pancreatic ductal adenocarcinomas largely due to the suppressive immune milieu in such tumors. Critically, the genomic alteration pattern is believed to impact cancer immune environment. Surprisingly, KRAS gene mutation is found in almost all pancreatic ductal adenocarcinomas. Moreover, KRAS mutation is indispensable for pancreatic carcinogenesis. On these bases, a relationship likely exists between this oncogene and immunosuppression in this cancer. During pancreatic carcinogenesis, KRAS mutation-driven events, such as metabolic reprogramming, cell autophagy, and persistent activation of the yes-associated protein pathway, converge to cause immune evasion. However, intriguingly, KRAS mutation can dictate a different immune environment in other types of adenocarcinoma, such as colorectal adenocarcinoma and lung adenocarcinoma. Overall, the KRAS mutation can drive an immunosuppression in pancreatic ductal adenocarcinomas or in colorectal carcinomas, but this mechanism is not true in KRAS-mutant lung adenocarcinomas, especially in the presence of TP53 inactivation. As a result, the response of these adenocarcinomas to checkpoint inhibitors will vary.

KRAS/LKB1 and KRAS/TP53 co-mutations create divergent immune signatures in lung adenocarcinomas.

Lung adenocarcinomas exhibit various patterns of genomic alterations. During the development of this cancer, KRAS serves as a driver oncogene with a relatively high mutational frequency. Emerging data suggest that lung adenocarcinomas with KRAS mutations can show enhanced PD-L1 expression and additional somatic mutations, thus linking the prospect of applying immune checkpoint blockade therapy to this disease. However, the responses of KRAS-mutant lung adenocarcinomas to this therapy are distinct, which is largely attributed to the heterogeneity in the tumoral immune milieus. Recently, it was revealed that KRAS-mutant lung adenocarcinomas simultaneously expressing either a LKB1 or TP53 mutation typically have different immune profiles of their tumours: tumours with a KRAS/TP53 co-mutation generally present with a significant upregulation of PD-L1 expression and tumoricidal T-cell accumulation, and those with a KRAS/LKB1 co-mutation are frequently negative for PD-L1 expression and have few tumoricidal immune infiltrates. In this regard, interrogating TP53 or LKB1 mutation in addition to PD-L1 expression will be promising in guiding clinical use of immune checkpoint blockade therapy for KRAS-mutant lung adenocarcinomas.

Metastatic thymic-enteric adenocarcinoma responding to chemoradiation plus anti-angiogenic therapy: A case report.

BACKGROUND: Thymic-enteric adenocarcinoma with positive expression of CDX2 and CK20 is rare in adults, with only 16 reported cases. However, standard treatment options for this type of thymic adenocarcinoma has not yet been established. Therefore, we report a case of stage IV thymic-enteric adenocarcinoma treated with radiotherapy, chemotherapy, and anti-angiogenesis therapy. CASE SUMMARY: We report a case of thymic-enteric adenocarcinoma occurring in a 44-year-old woman. The tumor was considered unresectable owing to its invasiveness. The patient was treated with six cycles of oxaliplatin (130 mg/m2, day 1) and capecitabine (1000 mg/m2 BID, days 1-14). During the first three cycles of chemotherapy, concurrent radiotherapy (60 Gy/30 fractions) and anti-angiogenic therapy using apatinib were recommended. The primary tumor achieved partial remission based on the Response Evaluation Criteria in Solid Tumors. During follow-up, there was no evidence of disease relapse, except a high serum CA19-9 level. The patient is alive and regularly followed. Based on the previous literature and the present case, we believe that early diagnosis of thymic-enteric adenocarcinoma is important. CONCLUSION: XELOX (capecitabine plus oxaliplatin) combined with radiotherapy is an optional therapy for inoperable thymic-enteric adenocarcinoma.

Bacterial dysbiosis incites Th17 cell revolt in irradiated gut.

Th17 cells are critical members in mediating immune responses of adaptive immunity. In humans and mice, gut is a main site where Th17 cells are resided, and Th17 cell polarization also occurs in the gut. This process can be mediated by many factors, such as commensal bacteria, dendritic cells and cytokines, such as TGF-ß and IL-6. Physiologically, polarized Th17 cells function in anti-infection and maintaining the integrity of intestinal epithelium. However, Th17 cells are plastic. For example, they will become pro-inflammatory cells if being exposed to IL-23. The pathogenic roles of Th17 cells have been well documented in inflammatory bowel disease. Besides, Th17 cells can accumulate in irradiated gut as well. Critically, radiation enteritis and inflammatory bowel disease present several similarities in disease pathology and pathophysiology. Herein, bacterial dysbiosis highly correlates with the pathogenicity of Th17 cells in inflammatory bowel disease. To our knowledge, radiation serves as a factor in inducing bacterial dysbiosis. Using this action, can Th17 cells be incited to promote inflammation in irradiated gut? In this review, we will sequentially introduce polarization of Th17 cells at steady state, radiation-induced Th17 accumulation in the gut, and advances in the management of radiation enteritis by using pharmacological therapy for bacterial dysbiosis.

Standard therapies: solutions for improving therapeutic effects of immune checkpoint inhibitors on colorectal cancer.

Immunotherapy using immune checkpoint inhibitors has opened a new era for cancer management. In colorectal cancer, patients with a phenotype of deficient mismatch repair or high microsatellite instability benefit from immunotherapy. However, the response of rest cases to immunotherapy alone is still poor. Nevertheless, preclinical data have revealed that either ionizing irradiation or chemotherapy can improve the tumoral immune milieu, because these approaches can induce immunogenic cell death among cancer cells. In this regard, combination use of standard therapy plus immunotherapy should be feasible. In this review, we will introduce the specific roles of standard therapies, including radiotherapy, chemotherapy, antiangiogenic and anti-EGFR therapy, in improving therapeutic effect of immune checkpoint inhibitors on colorectal cancer.

Colorectal Cancer Immune Infiltrates: Significance in Patient Prognosis and Immunotherapeutic Efficacy.

Colorectal cancer occurrence and progression involve multiple aspects of host immune deficiencies. In these events, immune cells vary their phenotypes and functions over time, thus enabling the immune microenvironment to be "tumor-inhibiting" as well as "tumor-promoting" as a whole. Because of the association of tumoricidal T cell infiltration with favorable survival in cancer patients, the Immunoscore system was established. Critically, the tumoral Immunoscore serves as an indicator of CRC patient prognosis independent of patient TNM stage and suggests that patients with high Immunoscores in their tumors have prolonged survival in general. Accordingly, stratifications according to tumoral Immunoscores provide new insights into CRC in terms of comparing disease severity, forecasting disease progression, and making treatment decisions. An important application of this system will be to shed light on candidate selection in immunotherapy for CRC, because the T cells responsible for determining the Immunoscore serve as responders to immune checkpoint inhibitors. However, the Immunoscore system merely provides a standard procedure for identifying the tumoral infiltration of cytotoxic and memory T cells, while information concerning the survival and function of these cells is still absent. Moreover, other infiltrates, such as dendritic cells, macrophages, and B cells, can still influence CRC prognosis, implying that those might also influence the therapeutic efficacy of immune checkpoint inhibitors. On these bases, this review is designed to introduce the Immunoscore system by presenting its clinical significance and application in CRC.

A case of durvalumab-treated double primary cancers of the colon and lung.

Cases of double primary cancers of the colon and lung are rare, and the treatment regimens are highly individualized. Here, we report a case of double primary cancers of the colon and lung. The patient underwent radical resection for cancer of the left colon (pT4aN0Mx, IIb). Two months later, he sought treatment due to chest pain and painful swelling in his left axilla for one month and was diagnosed with adenocarcinoma of the right lung (cT4N3M1c, stage IVB). At the time before receiving radical resection of the left colon tumor, a chest computed tomography examination showed a space-occupying lesion in the upper lobe of the right lung, but the histological analysis was not performed at that time because abdominal computed tomography examination suggested the presence of incomplete obstruction, and emergency radical resection for colon cancer was conducted. Molecular pathological examination of the lung mass at the most recent admission suggested KRAS mutation and strongly positive programmed cell death-ligand 1 (PD-L1). Considering the patient's pain and compression symptoms, he was given palliative radiotherapy for the lung lesion, followed by sequential durvalumab maintenance therapy, along with a capecitabine plus oxaliplatin (CAPOX) regimen for colon cancer for 3 months. The patient signed informed consent forms for all treatments. After the treatments, the patient achieved partial remission of the lung lesion and complete remission of the lymph node metastases in the neck and left axilla. The only toxic effects were chemotherapy-related grade II bone marrow suppression and grade I radiation-induced lung injury. No recurrence or metastasis was observed during the 6-month follow-up. After a trade-off between the efficacy and toxicity of the treatment regimen of double cancers, this patient was given an individualized treatment regimen-maintenance treatment with the low-toxicity durvalumab for anti-PD-L1 immunotherapy following palliative radiotherapy and evidence-supported 3-month CAPOX chemotherapy after surgery for high-risk stage II colon cancer. The regimen not only avoided possible toxic effects but also achieved a sufficient treatment intensity. We believe that the combined use of radiotherapy, chemotherapy and lowtoxicity immune-targeted drugs has good application prospects in the individualized treatment of patients with multiple cancers.

Mesenchymal Stem Cell-Derived Exosomes: Biological Function and Their Therapeutic Potential in Radiation Damage.

Radiation-induced damage is a common occurrence in cancer patients who undergo radiotherapy. In this setting, radiation-induced damage can be refractory because the regeneration responses of injured tissues or organs are not well stimulated. Mesenchymal stem cells have become ideal candidates for managing radiation-induced damage. Moreover, accumulating evidence suggests that exosomes derived from mesenchymal stem cells have a similar effect on repairing tissue damage mainly because these exosomes carry various bioactive substances, such as miRNAs, proteins and lipids, which can affect immunomodulation, angiogenesis, and cell survival and proliferation. Although the mechanisms by which mesenchymal stem cell-derived exosomes repair radiation damage have not been fully elucidated, we intend to translate their biological features into a radiation damage model and aim to provide new insight into the management of radiation damage.

Decoding epigenetic codes: new frontiers in exploring recovery from spinal cord injury.

Spinal cord injury that results in severe neurological disability is often incurable. The poor clinical outcome of spinal cord injury is mainly caused by the failure to reconstruct the injured neural circuits. Several intrinsic and extrinsic determinants contribute to this inability to reconnect. Epigenetic regulation acts as the driving force for multiple pathological and physiological processes in the central nervous system by modulating the expression of certain critical genes. Recent studies have demonstrated that post-SCI alteration of epigenetic landmarks is strongly associated with axon regeneration, glial activation and neurogenesis. These findings not only establish a theoretical foundation for further exploration of spinal cord injury, but also provide new avenues for the clinical treatment of spinal cord injury. This review focuses on the epigenetic regulation in axon regeneration and secondary spinal cord injury. Together, these discoveries are a selection of epigenetic-based prognosis biomarkers and attractive therapeutic targets in the treatment of spinal cord injury.

Gut commensal bacteria, Paneth cells and their relations to radiation enteropathy.

In steady state, the intestinal epithelium forms an important part of the gut barrier to defend against luminal bacterial attack. However, the intestinal epithelium is compromised by ionizing irradiation due to its inherent self-renewing capacity. In this process, small intestinal bacterial overgrowth is a critical event that reciprocally alters the immune milieu. In other words, intestinal bacterial dysbiosis induces inflammation in response to intestinal injuries, thus influencing the repair process of irradiated lesions. In fact, it is accepted that commensal bacteria can generally enhance the host radiation sensitivity. To address the determination of radiation sensitivity, we hypothesize that Paneth cells press a critical "button" because these cells are central to intestinal health and disease by using their peptides, which are responsible for controlling stem cell development in the small intestine and luminal bacterial diversity. Herein, the most important question is whether Paneth cells alter their secretion profiles in the situation of ionizing irradiation. On this basis, the tolerance of Paneth cells to ionizing radiation and related mechanisms by which radiation affects Paneth cell survival and death will be discussed in this review. We hope that the relevant results will be helpful in developing new approaches against radiation enteropathy.