Pectin supplement significantly enhanced the anti-PD-1 efficacy in tumor-bearing mice humanized with gut microbiota from patients with colorectal cancer.

Background: Anti-PD-1-based immunotherapy has emerged as a promising therapy for several cancers. However, it only benefits a small subset of colorectal cancer (CRC) patients. Mounting data supports the pivotal role of gut microbiota in shaping immune system. Pectin, a widely consumed soluble fiber, has been reported to ameliorate the imbalance of gut microbiota. Therefore, we aimed to explore the effect and the underlying mechanisms of pectin in improving anti-PD-1 mAb efficacy. Methods: The C57BL/6 mice were treated with a broad-spectrum antibiotic (ATB) cocktail to depleted endogenous gut microbiota and subsequently humanized with feces from healthy controls or newly diagnosed CRC patients. The antitumor efficacies of anti-PD-1 mAb combined with or without pectin were assessed using these mice. Flow cytometry and immunohistochemistry (IHC) were conducted to investigate the tumor immune microenvironment after treatment. The gut microbiota profiles and short-chain fatty acids (SCFAs) levels were determined by 16S ribosomal RNA (16S rRNA) gene sequencing and gas chromatography-mass spectrometry (GC-MS), respectively. The effect of gut microbiota on anti-PD-1 mAb efficacy after pectin supplement was further tested by fecal microbiota transplantation (FMT). Results: The anti-PD-1 mAb efficacy was largely impaired in the mice humanized with feces from newly diagnosed CRC patients compared to those from healthy controls. However, pectin significantly enhanced the anti-PD-1 mAb efficacy in the tumor-bearing mice humanized with CRC patient gut microbiota. Flow cytometry and IHC analysis revealed increased T cell infiltration and activation in the tumor microenvironment of mice treated with anti-PD-1 mAb plus pectin. In vivo depletion of CD8+ T cells diminished the anti-tumor effect of anti-PD-1 mAb combined with pectin. 16S rRNA gene sequencing showed that pectin significantly increased gut microbial diversity and beneficially regulated microbial composition. In addition, we identified unique bacterial modules that were significantly enriched in the anti-PD-1 mAb + pectin group, which composed of butyrate-producing bacteria indicative of good response to immunotherapy. Meanwhile, GC-MS showed that pectin altered the level of SCFA butyrate. Furthermore, butyrate, a main product of dietary fiber in gut microbial fermentation, was found to be sufficient to promote T cells infiltration and thus enhance the efficacy of anti-PD-1 mAb. In addition, FMT demonstrated the effects of pectin were dependent on gut microbiota. Importantly, the beneficial effects of pectin were confirmed in the mice humanized with gut microbiota from patient with resistance to anti-PD-1 mAb. Conclusion: Pectin facilitated the anti-PD-1 mAb efficacy in CRC via regulating the T cell infiltration in the tumor microenvironment, which was potentially mediated by the metabolite butyrate.

Zhang SL ，Mao YQ ，Zhang ZY ，Li ZM ，Kong CY ，Chen HL ，Cai PR ，Han B ，Ye T ，Wang LS ... -  《Theranostics》

PRM1201 effectively inhibits colorectal cancer metastasis via shaping gut microbiota and short- chain fatty acids.

Jia R ，Shao S ，Zhang P ，Yuan Y ，Rong W ，An Z ，Lv S ，Feng Y ，Liu N ，Feng Q ，Wang Y ，Li Q ... -  《-》

Echinacoside inhibits colorectal cancer metastasis via modulating the gut microbiota and suppressing the PI3K/AKT signaling pathway.

Echinacoside (ECH) is the dominant phenylethanoid glycoside-structured compound identified from our developed herbal formula Huangci granule, which has been previously reported to inhibit the invasion and metastasis of CRC and prolong patients' disease-free survival duration. Though ECH has inhibitory activity against aggressive colorectal cancer (CRC) cells, its anti-metastasis effect in vivo and the action mechanism is undetermined. Given that ECH has an extremely low bioavailability and gut microbiota drives the CRC progression, we hypothesized that ECH could inhibit metastatic CRC by targeting the gut microbiome. The purpose of this study was to investigate the impact of ECH on colorectal cancer liver metastasis in vivo and its potential mechanisms. An intrasplenic injection-induced liver metastatic model was established to examine the efficiency of ECH on tumor metastasis in vivo. Fecal microbiota from the model group and the ECH group were separately transplanted into pseudo-sterile CRLM mice in order to verify the role of gut flora in the ECH anti-metastatic effect. The 16S rRNA gene sequence was applied to analyze the structure and composition of the gut microbiota after ECH intervention, and the effect of ECH on short-chain fatty acid (SCFAs)-producing bacteria growth was proven by anaerobic culturing in vitro. GC-MS was applied to quantitatively analyze the serum SCFAs levels in mice. RNA-seq was performed to detect the gene changes involving tumor-promoting signaling pathway. ECH inhibited CRC metastasis in a dose-dependent manner in the metastatic colorectal cancer (mCRC) mouse model. Manipulation of gut bacteria in the mCRC mouse model further proved that SCFA-generating gut bacteria played an indispensable role in mediating the antimetastatic action of ECH. Under an anaerobic condition, ECH benefited SCFA-producing microbiota without affecting the total bacterial load, presenting a dose-dependent promotion on the growth of a butyrate producer, Faecalibacterium prausnitzii (F.p). Furthermore, ECH-reshaped or F.p-colonized microbiota with a high butyrate-producing capability inhibited liver metastasis by suppressing PI3K/AKT signaling and reversing the epithelial-mesenchymal transition (EMT) process, whereas this anti-metastatic ability was abrogated by the butyrate synthase inhibitor heptanoyl-CoA. This study demonstrated that ECH exhibits oral anti-metastatic efficacy by facilitating butyrate-producing gut bacteria, which downregulates PI3K/AKT signaling and EMT. It hints at a novel role for ECH in CRC therapy.

Wei J ，Zheng Z ，Hou X ，Jia F ，Yuan Y ，Yuan F ，He F ，Hu L ，Zhao L ... -  《-》

Chang Wei Qing Decoction enhances the anti-tumor effect of PD-1 inhibitor therapy by regulating the immune microenvironment and gut microbiota in colorectal cancer.

The anti-tumor effect of anti-PD-1 antibody has long been shown to be strongly related to the tumor immune microenvironment (TIME). This study aimed to mechanistically assess whether Chang Wei Qing (CWQ) Decoction can enhance the anti-tumor effect of PD-1 inhibitor therapy. PD-1 inhibitor therapy showed the significant anti-tumor effect in patients with mismatch repair-deficient/microsatellite instability-high (dMMR/MSI-H) colorectal cancer (CRC), rather than those with mismatch repair-proficient/microsatellite stable (pMMR/MSS) CRC. Hence, immunofluorescence double-label staining was utilized to explore the difference in the TIME between dMMR/MSI-H and pMMR/MSS CRC patients. Flow cytometry was used to analyze T-lymphocytes in tumors from mice. Western blot was used to measure the expression of PD-L1 protein in mouse tumors. The intestinal mucosal barrier of mice was evaluated by hematoxylin-eosin staining and immunohistochemistry. 16S rRNA-gene sequencing was used to examine the structure of the gut microbiota in mice. Subsequently, Spearmanapos;s correlation analysis was used to analyze the relationship between the gut microbiota and tumor-infiltrating T-lymphocytes. The results showed that dMMR/MSI-H CRC patients had more CD8+T cells and higher expression of PD-1 and PD-L1 proteins. In vivo, CWQ enhanced the anti-tumor effect of anti-PD-1 antibody and increased the infiltration of CD8+ and PD-1+CD8+ T cells in tumors. Additionally, the combination of CWQ with anti-PD-1 antibody resulted in lower inflammation in the intestinal mucosa than that induced by anti-PD-1 antibody alone. CWQ and anti-PD-1 antibody co-treatment upregulated PD-L1 protein and reduced the abundance of Bacteroides in the gut microbiota but increased the abundance of Akkermansia,Firmicutes, andActinobacteria. Additionally, the proportion of infiltrated CD8+PD-1+, CD8+, and CD3+ T cells were found to be positively correlated with the abundance of Akkermansia. Accordingly, CWQ may modulate the TIME by modifying the gut microbiota and consequently enhance the anti-tumor effect of PD-1 inhibitor therapy.

Wang T ，Wu L ，Wang S ，Shi X ，Liu H ，Deng W ... -  《-》

Sugar Beet Pectin Supplementation Did Not Alter Profiles of Fecal Microbiota and Exhaled Breath in Healthy Young Adults and Healthy Elderly.

An R ，Wilms E ，Smolinska A ，Hermes GDA ，Masclee AAM ，de Vos P ，Schols HA ，van Schooten FJ ，Smidt H ，Jonkers DMAE ，Zoetendal EG ，Troost FJ ... -  《Nutrients》