The prevalence of Lynch syndrome (LS) varies significantly in different populations, suggesting that ethnic features might play an important role. We enrolled 3330 consecutive Chinese patients who had surgical resection for newly diagnosed colorectal cancer. Universal screening for LS was implemented, including immunohistochemistry for mismatch repair (MMR) proteins, BRAF V600E mutation test and germline sequencing. Among the 3250 eligible patients, MMR protein deficiency (dMMR) was detected in 330 (10.2%) patients. Ninety-three patients (2.9%) were diagnosed with LS. Nine (9.7%) patients with LS fulfilled Amsterdam criteria II and 76 (81.7%) met the revised Bethesda guidelines. Only 15 (9.7%) patients with absence of MLH1 on IHC had BRAF V600E mutation. One third (33/99) of the MMR gene mutations have not been reported previously. The age of onset indicates risk of LS in patients with dMMR tumors. For patients older than 65 years, only 2 patients (5.7%) fulfilling revised Bethesda guidelines were diagnosed with LS. Selective sequencing of all cases with dMMR diagnosed at or below age 65 years and only of those dMMR cases older than 65 years who fulfill revised Bethesda guidelines results in 8.2% fewer cases requiring germline testing without missing any LS diagnoses. While the prevalence of LS in Chinese patients is similar to that of Western populations, the spectrum of constitutional mutations and frequency of BRAF V600E mutation is different. Patients older than 65 years who do not meet the revised Bethesda guidelines have a low risk of LS, suggesting germline sequencing might not be necessary in this population. What's new?The prevalence of Lynch syndrome (LS) varies significantly in different ethnic populations. In this study, the authors screened more than 3000 Chinese colorectal cancer patients for mutations associated with LS, including mismatch repair (MMR) and BRAF V600E mutations. They found that, while the prevalence of LS in Chinese patients is similar to that of Western populations, the spectrum of mutations is different, including many not previously reported. Older patients had a decreased risk of LS, suggesting that germline sequencing may not be necessary in this population.

Reperfusion of the ischemic intestine often leads to drive distant organ injury, especially injuries associated with hepatocellular dysfunction. The precise molecular mechanisms and effective multiple organ protection strategies remain to be developed. In the current study, significant remote liver dysfunction was found after 6 hours of reperfusion according to increased histopathological scores, serum lactate dehydrogenase (LDH), alanine aminotransferase (ALT)/aspartate aminotransferase (AST) levels, as well as enhanced bacterial translocation in a rat intestinal ischemia/reperfusion (I/R) injury model. Moreover, receptor‐interacting protein kinase 1/3 (RIP1/3) and phosphorylated‐MLKL expressions in tissue were greatly elevated, indicating that necroptosis occurred and resulted in acute remote liver function impairment. Inhibiting the necroptotic pathway attenuated HMGB1 cytoplasm translocation and tissue damage. Meanwhile, macrophage‐depletion study demonstrated that Kupffer cells (KCs) are responsible for liver damage. Blocking HMGB1 partially restored the liver function via suppressed hepatocyte necroptosis, tissue inflammation, hepatic KCs, and circulating macrophages M1 polarization. What’s more, HMGB1 neutralization further protects against intestinal I/R‐associated liver damage in microbiota‐depleted rats. Therefore, intestinal I/R is likely associated with acute liver damage due to hepatocyte necroptosis, and which could be ameliorated by Nec‐1 administration and HMGB1 inhibition with the neutralizing antibody and inhibitor. Necroptosis inhibition and HMGB1 neutralization/inhibition, may emerge as effective pharmacological therapies to minimize intestinal I/R‐induced acute remote organ dysfunction.

Cell death is an important biological process that is believed to have a central role in intestinal ischaemia/reperfusion (I/R) injury. While the apoptosis inhibition is pivotal in preventing intestinal I/R, how necrotic cell death is regulated remains unknown. Necroptosis represents a newly discovered form of programmed cell death that combines the features of both apoptosis and necrosis, and it has been implicated in the development of a range of inflammatory diseases. Here, we show that receptor‐interacting protein 1/3 (RIP1/3) kinase and mixed lineage kinase domain‐like protein recruitment mediates necroptosis in a rat model of ischaemic intestinal injury in vivo. Furthermore, necroptosis was specifically blocked by the RIP1 kinase inhibitor necrostatin‐1. In addition, the combined treatment of necrostatin‐1 and the pan‐caspase inhibitor Z‐VAD acted synergistically to protect against intestinal I/R injury, and these two pathways can be converted to one another when one is inhibited. In vitro, necrostatin‐1 pre‐treatment reduced the necroptotic death of oxygen‐glucose deprivation challenged intestinal epithelial cell‐6 cells, which in turn dampened the production of pro‐inflammatory cytokines (tumour necrosis factor‐α and interleukin‐1β), and suppressed high‐mobility group box‐1 (HMGB1) translocation from the nucleus to the cytoplasm and the subsequent release of HMGB1 into the supernatant, thus decreasing the activation of Toll‐like receptor 4 and the receptor for advanced glycation end products. Collectively, our study reveals a robust RIP1/RIP3‐dependent necroptosis pathway in intestinal I/R‐induced intestinal injury in vivo and in vitro and suggests that the HMGB1 signalling is highly involved in this process, making it a novel therapeutic target for acute ischaemic intestinal injury.

PurposeTumor stroma cells play an important role in the carcinogenesis and progression of cancer. The aim of the present investigation was to explore the predictive role of carcinoma-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs) in nasopharyngeal carcinoma (NPC).Patients and methodsThe densities of CAFs and TAMs were measured by immunohistochemistry staining for α-smooth muscle actin (α-SMA), CD68, and CD163 in two sets of tissue microarrays including 260 pretreatment NPC tissues, that is, a training test comprising of 152 patients and a validation set comprising of 108 patients. Chi-square tests were performed for comparisons among the groups. Survival rates were estimated by using the Kaplan–Meier method and compared with log-rank tests. Cox proportional hazards models were used to identify significant independent variables.ResultsPatients older than 50 years showed a lower expression of CD68, and there was a positive relationship between the densities of CAFs and CD163+ TAMs (p=0.001). In the multivariate analysis of the training test, both α-SMA and CD163 were independent prognostic factors for overall survival and progression-free survival (all p<0.05). Based on the expression levels of α-SMA and CD163, patients were categorized into three groups: high-risk, intermediate-risk, and low-risk groups according to both high, either high, and both low, respectively. Survival analysis and Cox multivariate analysis showed that the risk groups based on α-SMA and CD163 expression were independent predictors for the survival of patients with NPC in the training test, which was also confirmed by the validation test.ConclusionA patient’s risk group based on the level of CD163+ TAMs and CAFs was an independent predictor of survival, which may facilitate patient counseling and individualized treatment.

BackgroundDickkopf 1 (DKK1) is associated with tumor progression. However, whether DKK1 influences the tumor response to programmed cell death protein 1 (PD-1) blockade in colorectal cancers (CRCs) with deficient mismatch repair (dMMR) or microsatellite instability (MSI) has never been clarified.MethodsTumor tissues from 80 patients with dMMR CRC were evaluated for DKK1 expression and immune status via immunohistochemistry. Serum DKK1 was measured in another set of 43 patients who received PD-1 blockade therapy. CT26 cells and dMMR CRC organoids were cocultured with T cells, and CT26-grafted BALB/c mice were also constructed. T-cell cytotoxicity was assessed by apoptosis assays and flow cytometry. The pathway through which DKK1 regulates CD8+ T cells was investigated using RNA sequencing, and chromatin immunoprecipitation and luciferase reporter assays were conducted to determine the downstream transcription factors of DKK1.ResultsElevated DKK1 expression was associated with recurrence and decreased CD8+ T-cell infiltration in dMMR CRCs, and patients with high-serum DKK1 had a poor response to PD-1 blockade. RNA interference or neutralization of DKK1 in CRC cells enhanced CD8+ T-cell cytotoxicity, while DKK1 decreased T-bet expression and activated GSK3β in CD8+ T cells. In addition, E2F1, a downstream transcription factor of GSK3β, directly upregulated T-bet expression. In organoid models, the proportion of apoptotic cells was elevated after individual neutralization of PD-1 or DKK1 and was further increased on combined neutralization of PD-1 and DKK1.ConclusionsDKK1 suppressed the antitumor immune reaction through the GSK3β/E2F1/T-bet axis in CD8+ T cells. Elevated serum DKK1 predicted poor tumor response to PD-1 blockade in dMMR/MSI CRCs, and DKK1 neutralization may restore sensitivity to PD-1 blockade.