Single-cell transcriptome analysis reveals immunosuppressive landscape in overweight and obese colorectal cancer.

BACKGROUND: Overweight and obesity are established risk factors for various types of cancers including colorectal cancer (CRC). However the underlying molecular mechanisms remain unclear. An in-depth understanding of the oncologic characteristics of overweight and obese CRC at the single-cell level can provide valuable insights for the development of more effective treatment strategies for CRC. METHODS: We conducted single-cell RNA sequencing (scRNA-seq) analysis on tumor and adjacent normal colorectal samples from 15 overweight/obese and 15 normal-weight CRC patients. Immunological and metabolic differences between overweight/obese CRC and non-obese CRC were characterized. RESULTS: We obtained single-cell transcriptomics data from a total of 192,785 cells across all samples. By evaluating marker gene expression patterns, we annotated nine main cell types in the CRC ecosystem. Specifically, we found that the cytotoxic function of effector T cells and NK cells was impaired in overweight/obese CRC compared with non-obese CRC, relating to its metabolic dysregulation. CD4+T cells in overweight/obese CRC exhibited higher expression of immune checkpoint molecules. The antigen-presenting ability of DCs and B cells is down-regulated in overweight/obese CRC, which may further aggravate the immunosuppression of overweight/obese CRC. Additionally, dysfunctional stromal cells were identified, potentially promoting invasion and metastasis in overweight/obese CRC. Furthermore, we discovered the up-regulated metabolism of glycolysis and lipids of tumor cells in overweight/obese CRC, which may impact the metabolism and function of immune cells. We also identified inhibitory interactions between tumor cells and T cells in overweight/obese CRC. CONCLUSIONS: The study demonstrated that overweight/obese CRC has a more immunosuppressive microenvironment and distinct metabolic reprogramming characterized by increased of glycolysis and lipid metabolism. These findings may have implications for the development of novel therapeutic strategies for overweight/obese CRC patients.

Stapled transperineal rectovaginal fistula repair for low- and mid-level rectovaginal fistulas: A comparison study with rectal mucosal advancement flap repair.

BACKGROUND: As an innovative treatment, stapled transperineal rectovaginal fistula repair (STR) for rectovaginal fistula (RVF) has demonstrated effectiveness in preliminary reports. This study aims to compare STR with rectal mucosal advancement flap repair (RAF), a widely utilized surgical procedure, for the surgical outcome of the low- and mid-level RVF. METHODS: In this retrospective cohort study, patients with low- and mid-level RVF who underwent STR or RAF were included from both the Sixth Affiliated Hospital of Sun Yat-sen University and Xi'an Daxing Hospital. Among the 99 total patients, 77 underwent STR and 22 underwent RAF. Patient demographics, operative data, and outcomes were collected and analyzed. Recurrence rate and associated risk factors were evaluated. RESULTS: There were no statistically significant differences among patients in terms of clinical characteristics like age, BMI, aetiology, and fistula features. During the follow-up period of 20 months (interquartile range 3.0-41.8 months), a total of 28 patients relapsed, with a significantly lower recurrence rate in the STR group (20.8 %) than in the RAF group (54.6 %) (P = 0.005). In the multivariate Cox analysis, STR was an independent protective factor against recurrence (HR: 0.37, 95%CI: 0.17-0.79, P = 0.01). Logistic regression indicated that there was no statistically significant difference between these two procedures in terms of surgical complications (OR: 0.53, 95%CI: 0.19-1.48, P = 0.23). CONCLUSION: For low- and mid-level RVF, STR may be an alternative option for treatment modality that offers a lower recurrence rate, without observed disadvantage in terms of surgical complication rates.

Single-cell RNA sequencing reveals cellular dynamics and therapeutic effects of astragaloside IV in slow transit constipation.

The cellular characteristics of intestinal cells involved in the therapeutic effects of astragaloside IV (AS-IV) for treating slow transit constipation (STC) remain unclear. This study aimed to determine the dynamics of colon tissue cells in the STC model and investigate the effects of AS-IV treatment by single-cell RNA sequencing (scRNA-seq). STC mouse models were developed using loperamide, with subsequent treatment using AS-IV. Colon tissues and feces were collected for scRNA-seq and targeted short-chain fatty acid quantification. We integrated scRNA-seq data with network pharmacology to analyze the effect of AS-IV on constipation. AS-IV showed improvement in defecation for STC mice induced by loperamide. Notably, in STC mice, epithelial cells, T cells, B cells, and fibroblasts demonstrated alterations in cell proportions and dysfunctions, which AS-IV partially rectified. AS-IV has the potential to modulate the metabolic pathway of epithelial cells through its interaction with peroxisome proliferator-activated receptor gamma (PPARγ). AS-IV reinstated fecal butyrate levels and improved energy metabolism in epithelial cells. The proportion of naïve CD4+T cells is elevated in STC, and the differentiation of these cells into regulatory T cells (Treg) is regulated by B cells and fibroblasts through the interaction of ligand-receptor pairs. AS-IV treatment can partially alleviate this trend. The status of fibroblasts in STC undergoes alterations, and the FB_C4_Adamdec1 subset, associated with angiogenesis and the Wingless-related integration (Wnt) pathway, emerges. Our comprehensive analysis identifies perturbations of epithelial cells and tissue microenvironment cells in STC and elucidates mechanisms underlying the therapeutic efficacy of AS-IV.

Astragaloside IV improves slow transit constipation by regulating gut microbiota and enterochromaffin cells.

Purpose: Slow transit constipation (STC) is a common gastrointestinal disorder characterized by altered gut microbiota and reduced number of enterochromaffin cells (ECs). Astragaloside IV (AS-IV), a low drug permeability saponin, has showed beneficial effects on patients with STC. However, the specific mechanism by which AS-IV regulates STC remains unclear. In this study, we aimed to investigate the effect of AS-IV on STC and its associated mechanisms involving gut microbiota. Methods: The effect of AS-IV on STC was evaluated on STC mice induced with loperamide. We measured defecation frequency, intestinal mobility, ECs loss, and colonic lesions in STC mice treated with AS-IV. We also analyzed the changes in gut microbiota and metabolites after AS-IV treatment. Moreover, we investigated the relationship between specific gut microbes and altered fecal metabolites, such as 3-bromotyrosine (3-BrY). We also conducted in vitro experiments to investigate the effect of 3-BrY on caspase-dependent apoptosis of ECs and the activation of the p38 MAPK and ERK signaling pathways induced by loperamide. Results: AS-IV treatment promoted defecation, improved intestinal mobility, suppressed ECs loss, and alleviated colonic lesions in STC mice. AS-IV treatment also affected gut microbiota and metabolites, with a significant correlation between specific gut microbes and altered fecal metabolites such as 3-BrY. Furthermore, 3-BrY may potentially reduce caspase-dependent apoptosis of ECs and protect cell survival by inhibiting the activation of the p38 MAPK and ERK signaling pathways induced by loperamide. Conclusion: Our findings suggest that changes in gut microbiota and ECs mediated the therapeutic effect of STC by AS-IV. These results provide a basis for the use of AS-IV as a prebiotic agent for treating STC. The specific mechanism by which AS-IV regulates gut microbiota and ECs warrants further investigation.

A magnetic resonance imaging-based decision-making tool for predicting complex anal fistulas healing in the early postoperative period.

BACKGROUND: Magnetic resonance imaging (MRI) has excellent accuracy in diagnosing preoperative lesions before anal fistula surgery. However, MRI is not good in identifying early recurrent lesions and effective methods for quantitative assessment of fistula healing are still warranted. This retrospective study aimed to develop and validate a specific MRI-based nomogram model to predict fistula healing during the early postoperative period. METHODS: Patients with complex cryptoglandular anal fistulas who underwent surgery between January 2017 and October 2020 were included in this study. MRI features and clinical parameters were analyzed using univariate and multivariate logistic regression analysis. A nomogram for predicting fistula healing was constructed and validated. RESULTS: In total, 200 patients were included, of whom 186 (93%) were male, with a median age of 36 (18-65) years. Of the fistulas, 58.5% were classified as transsphincteric and 19.5% as suprasphincteric. The data were randomly divided into the training cohort and testing cohort at a ratio of 7:3. Logistic analysis revealed that CNR, ADC, alcohol intake history, and suprasphincteric fistula were significantly correlated with fistula healing. These four predictors were used to construct a predictive nomogram model in the training cohort. AUC was 0.880 and 0.847 for the training and testing cohorts, respectively. Moreover, the decision and calibration curves showed high coherence between the predicted and actual probabilities of fistula healing. CONCLUSIONS: We developed a predictive model and constructed a nomogram to predict fistula healing during the early postoperative period. This model showed good performance and may be clinically utilized for the management of anal fistulas.

Cancer-associated fibroblasts undergoing neoadjuvant chemotherapy suppress rectal cancer revealed by single-cell and spatial transcriptomics.

Neoadjuvant chemotherapy (NAC) for rectal cancer (RC) shows promising clinical response. The modulation of the tumor microenvironment (TME) by NAC and its association with therapeutic response remain unclear. Here, we use single-cell RNA sequencing and spatial transcriptome sequencing to examine the cell dynamics in 29 patients with RC, who are sampled pairwise before and after treatment. We construct a high-resolution cellular dynamic landscape remodeled by NAC and their associations with therapeutic response. NAC markedly reshapes the populations of cancer-associated fibroblasts (CAFs), which is strongly associated with therapeutic response. The remodeled CAF subsets regulate the TME through spatial recruitment and crosstalk to activate immunity and suppress tumor progression through multiple cytokines, including CXCL12, SLIT2, and DCN. In contrast, the epithelial-mesenchymal transition of malignant cells is upregulated by CAF_FAP through MIR4435-2HG induction, resulting in worse outcomes. Our study demonstrates that NAC inhibits tumor progression and modulates the TME by remodeling CAFs.

Single-Cell RNA Sequencing Reveals Heterogeneity in the Tumor Microenvironment between Young-Onset and Old-Onset Colorectal Cancer.

BACKGROUND: The incidence of sporadic young-onset colorectal cancer (yCRC) is increasing. Compared with old-onset colorectal cancer (oCRC), yCRC has different clinical and molecular characteristics. However, the difference in the tumor microenvironment (TME) between yCRC and oCRC remains unclear. METHODS: Fourteen untreated CRC tumor samples were subjected to single-cell RNA sequencing analysis. RESULTS: B cells and naïve T cells are enriched in yCRC, while effector T cells and plasma cells are enriched in oCRC. Effector T cells of yCRC show decreased interferon-gamma response and proliferative activity; meanwhile, Treg cells in yCRC show stronger oxidative phosphorylation and TGF-ß signaling than that in oCRC. The down-regulated immune response of T cells in yCRC may be regulated by immune and malignant cells, as we observed a downregulation of antigen presentation and immune activations in B cells, dendritic cells, and macrophages. Finally, we identified malignant cells in yCRC and oCRC with high heterogeneity and revealed their interactions with immune cells in the TME. CONCLUSIONS: Our data reveal significant differences of TME between yCRC and oCRC, of which the TME of yCRC is more immunosuppressive than oCRC. Malignant cells play an essential role in the formation of the suppressive tumor immune microenvironment.

Mucocele: a rare complication following stapled haemorrhoidopexy.

BACKGROUND: Stapled haemorrhoidopexy (SH) has resulted in a unique collection of procedural complications with postoperative mucocele a particularly rare example. This study is designed to comprehensively describe the characteristics of rectal mucocele and discuss its pathogenesis following SH surgery. METHODS: A database of patients presenting with a rectal mucocele following an SH procedure was established and studied retrospectively. RESULTS: Seven patients (5 males; median age 32 years, range 20-75 years) were identified. All patients complained of variable anal discomfort with 5/7 presenting with inconstant anal pain, 2 with de novo evacuatory difficulty. These cases appeared at a median time of 6 months (range 2-84 months) after SH surgery. CONCLUSION: Rectal Mucocele develops when mucosal fragments become embedded and isolated under the mucosa. It is a preventable complication of SH surgery by ensuring correct purse string placement prior to stapled haemorrhoid excision.