Corrigendum: Endothelial ß-catenin deficiency causes blood-brain barrier breakdown via enhancing the paracellular and transcellular permeability.

[This corrects the article DOI: 10.3389/fnmol.2022.895429.].

A specific enterotype derived from gut microbiome of older individuals enables favorable responses to immune checkpoint blockade therapy.

Immunotherapy has revolutionized cancer treatment, but inconsistent responses persist. Our study delves into the intriguing phenomenon of enhanced immunotherapy sensitivity in older individuals with cancers. Through a meta-analysis encompassing 25 small-to-mid-sized trials of immune checkpoint blockade (ICB), we demonstrate that older individuals exhibit heightened responsiveness to ICB therapy. To understand the underlying mechanism, we reanalyze single-cell RNA sequencing (scRNA-seq) data from multiple studies and unveil distinct upregulation of exhausted and cytotoxic T cell markers within the tumor microenvironment (TME) of older patients. Recognizing the potential role of gut microbiota in modulating the efficacy of immunotherapy, we identify an aging-enriched enterotype linked to improved immunotherapy outcomes in older patients. Fecal microbiota transplantation experiments in mice confirm the therapeutic potential of the aging-enriched enterotype, enhancing treatment sensitivity and reshaping the TME. Our discoveries confront the prevailing paradox and provide encouraging paths for tailoring cancer immunotherapy strategies according to an individual's gut microbiome profile.

Unveiling the hidden players: exploring the role of gut mycobiome in cancer development and treatment dynamics.

The role of gut fungal species in tumor-related processes remains largely unexplored, with most studies still focusing on fungal infections. This review examines the accumulating evidence suggesting the involvement of commensal and pathogenic fungi in cancer biological process, including oncogenesis, progression, and treatment response. Mechanisms explored include fungal influence on host immunity, secretion of bioactive toxins/metabolites, interaction with bacterial commensals, and migration to other tissues in certain types of cancers. Attempts to utilize fungal molecular signatures for cancer diagnosis and fungal-derived products for treatment are discussed. A few studies highlight fungi's impact on the responsiveness and sensitivity to chemotherapy, radiotherapy, immunotherapy, and fecal microbiota transplant. Given the limited understanding and techniques in fungal research, the studies on gut fungi are still facing great challenges, despite having great potentials.

Deqformer: high-definition and scalable deep learning probe design method.

Target enrichment sequencing techniques are gaining widespread use in the field of genomics, prized for their economic efficiency and swift processing times. However, their success depends on the performance of probes and the evenness of sequencing depth among each probe. To accurately predict probe coverage depth, a model called Deqformer is proposed in this study. Deqformer utilizes the oligonucleotides sequence of each probe, drawing inspiration from Watson-Crick base pairing and incorporating two BERT encoders to capture the underlying information from the forward and reverse probe strands, respectively. The encoded data are combined with a feed-forward network to make precise predictions of sequencing depth. The performance of Deqformer is evaluated on four different datasets: SNP panel with 38 200 probes, lncRNA panel with 2000 probes, synthetic panel with 5899 probes and HD-Marker panel for Yesso scallop with 11 000 probes. The SNP and synthetic panels achieve impressive factor 3 of accuracy (F3acc) of 96.24% and 99.66% in 5-fold cross-validation. F3acc rates of over 87.33% and 72.56% are obtained when training on the SNP panel and evaluating performance on the lncRNA and HD-Marker datasets, respectively. Our analysis reveals that Deqformer effectively captures hybridization patterns, making it robust for accurate predictions in various scenarios. Deqformer leads to a novel perspective for probe design pipeline, aiming to enhance efficiency and effectiveness in probe design tasks.

Protocol to identify fungal profile from fecal metagenomes in cancer patients prior to immunotherapy.

Identifying fungal profiles from metagenomes is challenging due to an incomplete fungal database and limitations in the understanding of software. Here, we describe a protocol for analyzing the fecal metagenome of cancer patients prior to immunotherapy. We describe steps for raw metagenomic sequencing data retrieval, human genome and contaminants elimination, and assigning taxonomy labels to fungal reads. We then detail measures for assessing fungal alpha diversity and beta diversity, along with differential analysis. For complete details on the use and execution of this protocol, please refer to Xiaowen Huang et al.1.

Gut microbiome for predicting immune checkpoint blockade-associated adverse events.

BACKGROUND: The impact of the gut microbiome on the initiation and intensity of immune-related adverse events (irAEs) prompted by immune checkpoint inhibitors (ICIs) is widely acknowledged. Nevertheless, there is inconsistency in the gut microbial associations with irAEs reported across various studies. METHODS: We performed a comprehensive analysis leveraging a dataset that included published microbiome data (n = 317) and in-house generated data from 16S rRNA and shotgun metagenome samples of irAEs (n = 115). We utilized a machine learning-based approach, specifically the Random Forest (RF) algorithm, to construct a microbiome-based classifier capable of distinguishing between non-irAEs and irAEs. Additionally, we conducted a comprehensive analysis, integrating transcriptome and metagenome profiling, to explore potential underlying mechanisms. RESULTS: We identified specific microbial species capable of distinguishing between patients experiencing irAEs and non-irAEs. The RF classifier, developed using 14 microbial features, demonstrated robust discriminatory power between non-irAEs and irAEs (AUC = 0.88). Moreover, the predictive score from our classifier exhibited significant discriminative capability for identifying non-irAEs in two independent cohorts. Our functional analysis revealed that the altered microbiome in non-irAEs was characterized by an increased menaquinone biosynthesis, accompanied by elevated expression of rate-limiting enzymes menH and menC. Targeted metabolomics analysis further highlighted a notably higher abundance of menaquinone in the serum of patients who did not develop irAEs compared to the irAEs group. CONCLUSIONS: Our study underscores the potential of microbial biomarkers for predicting the onset of irAEs and highlights menaquinone, a metabolite derived from the microbiome community, as a possible selective therapeutic agent for modulating the occurrence of irAEs.

Production of recombinant HPV11/16 E6/E7-MBP-His6 fusion proteins and their potential to induce cytokine secretion by immune cells in peripheral blood.

Human papillomavirus (HPV) infection poses a significant threat to public health worldwide. Targeting the function of HPV E6 and E7 proteins and activating the host immune response against these proteins represent promising therapeutic strategies for combating HPV-related diseases. Consequently, the efficient production of soluble, high-purity E6 and E7 proteins is crucial for function and host immune response studies. In this context, we selected the pMCSG19 protein expression vector for Escherichia coli to produce soluble MBP-His6 tagged HPV11/16 E6/E7 proteins, achieving relatively high purity and yield. Notably, these proteins exhibited low toxicity to peripheral blood mononuclear cells (PBMCs) and did not compromise their viability. Additionally, the recombinant proteins were capable of inducing the secretion of multiple cytokines by immune cells in peripheral blood, indicating their potential to elicit immune responses. In conclusion, our study offers a novel approach for the production of HPV11/16 E6/E7 fusion proteins with relatively high purity and yield. The fusing HPV11/16 E6/E7 proteins to MBP-His6 tag may serve as a valuable method for large-scale protein production in future research endeavors.

Unveiling the Therapeutic Potential of Herba Epimedii: Enhancing Bone Healing Through Cytoskeletal Regulation of RhoA/Rock1 Pathway.

Herba Epimedii is widely used to promote bone healing, and their active ingredients are total flavonoids of Epimedium (TFE). Ras homolog gene family member A / Rho-associated protein kinase (RhoA/Rock), an important pathway regulating the cytoskeleton, has been proven to affect bone formation. However, whether TFE promotes bone healing via this pathway remains unclear. In this study, the therapeutic effects of TFE were estimated using micro-computed tomography and hematoxylin and eosin staining of pathological sections. F-actin in osteoblasts was stained to investigate the protective effects of TFE on the cytoskeleton. Its regulatory effects on the RhoA/Rock1 pathway were explored using RT-qPCR and Western blot analysis. Besides, flow cytometry, alkaline phosphatase and nodule calcification staining were performed to evaluate the effects on osteogenesis. The bone healing in rats was improved, the cytoskeletal damage in osteoblasts was reduced, the RhoA/Rock1 pathway was downregulated, and osteogenesis was enhanced after TFE treatment. Thus, TFE can promote bone formation at least partially by regulating the expression of key genes and proteins in the cytoskeleton. The findings of this study provided evidence for clinical applications and would contribute to a better understanding of Epimedium's mechanisms in treating bone defects.

Disruption of CerS6-mediated sphingolipid metabolism by FTO deficiency aggravates ulcerative colitis.

BACKGROUND AND AIMS: Deregulation of RNA N6-methyladenosine (m6A) modification in intestinal epithelial cells (IECs) influences intestinal immune cells and leads to intestinal inflammation. We studied the function of fat mass-and obesity-associated protein (FTO), one of the m6A demethylases, in patients with ulcerative colitis (UC). METHODS: We analysed colon tissues of Ftoflox/flox; Villin-cre mice and their Ftoflox/flox littermates with dextran sulfate sodium (DSS) using real-time PCR and 16s rRNA sequencing. RNA and methylated RNA immunoprecipitation sequencing were used to analyse immunocytes and IECs. Macrophages were treated with conditioned medium of FTO-knockdown MODE-K cells or sphingosine-1-phosphate (S1P) and analysed for gene expression. Liquid chromatograph mass spectrometry identified C16-ceramide. RESULTS: FTO downregulation was identified in our in-house cohort and external cohorts of UC patients. Dysbiosis of gut microbiota, increased infiltration of proinflammatory macrophages, and enhanced differentiation of Th17 cells were observed in Ftoflox/flox;Villin-cre mice under DSS treatment. FTO deficiency resulted in an increase in m6A modification and a decrease in mRNA stability of CerS6, the gene encoding ceramide synthetase, leading to the downregulation of CerS6 and the accumulation of S1P in IECs. Subsequentially, the secretion of S1P by IECs triggered proinflammatory macrophages to secrete serum amyloid A protein 1/3, ultimately inducing Th17 cell differentiation. In addition, through bioinformatic analysis and experimental validation, we identified UC patients with lower FTO expression might respond better to vedolizumab treatment. CONCLUSIONS: FTO downregulation promoted UC by decreasing CerS6 expression, leading to increased S1P accumulation in IECs and aggravating colitis via m6A-dependent mechanisms. Lower FTO expression in UC patients may enhance their response to vedolizumab treatment.

Cath-KP, a novel peptide derived from frog skin, prevents oxidative stress damage in a Parkinson's disease model.

Parkinson's disease (PD) is a neurodegenerative condition that results in dyskinesia, with oxidative stress playing a pivotal role in its progression. Antioxidant peptides may thus present therapeutic potential for PD. In this study, a novel cathelicidin peptide (Cath-KP; GCSGRFCNLFNNRRPGRLTLIHRPGGDKRTSTGLIYV) was identified from the skin of the Asiatic painted frog ( Kaloula pulchra). Structural analysis using circular dichroism and homology modeling revealed a unique αßß conformation for Cath-KP. In vitro experiments, including free radical scavenging and ferric-reducing antioxidant analyses, confirmed its antioxidant properties. Using the 1-methyl-4-phenylpyridinium ion (MPP +)-induced dopamine cell line and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mice, Cath-KP was found to penetrate cells and reach deep brain tissues, resulting in improved MPP +-induced cell viability and reduced oxidative stress-induced damage by promoting antioxidant enzyme expression and alleviating mitochondrial and intracellular reactive oxygen species accumulation through Sirtuin-1 (Sirt1)/Nuclear factor erythroid 2-related factor 2 (Nrf2) pathway activation. Both focal adhesion kinase (FAK) and p38 were also identified as regulatory elements. In the MPTP-induced PD mice, Cath-KP administration increased the number of tyrosine hydroxylase (TH)-positive neurons, restored TH content, and ameliorated dyskinesia. To the best of our knowledge, this study is the first to report on a cathelicidin peptide demonstrating potent antioxidant and neuroprotective properties in a PD model by targeting oxidative stress. These findings expand the known functions of cathelicidins, and hold promise for the development of therapeutic agents for PD.

Levofloxacin alleviates blood-brain barrier disruption following cerebral ischemia and reperfusion via directly inhibiting A-FABP.

Reperfusion therapy is currently the most effective treatment for acute ischemic stroke, but often results in secondary brain injury. Adipocyte fatty acid-binding protein (A-FABP, FABP4, or aP2) was shown to critically mediate cerebral ischemia/reperfusion (I/R) injury by exacerbating blood-brain barrier (BBB) disruption. However, no A-FABP inhibitors have been approved for clinical use due to safety issues. Here, we identified the therapeutic effect of levofloxacin, a widely used antibiotic displaying A-FABP inhibitory activity in vitro, on cerebral I/R injury and determined its target specificity and action mechanism in vivo. Using molecular docking and site-directed mutagenesis, we showed that levofloxacin inhibited A-FABP activity through interacting with the amino acid residue Asp76, Gln95, Arg126 of A-FABP. Accordingly, levofloxacin significantly inhibited A-FABP-induced JNK phosphorylation and expressions of proinflammatory factors and matrix metalloproteinase 9 (MMP-9) in mouse primary macrophages. In wild-type mice with transient middle cerebral artery occlusion, levofloxacin substantially mitigated BBB disruption and neuroinflammation, leading to reduced cerebral infarction, alleviated neurological outcomes, and improved survival. Mechanistically, levofloxacin decreased MMP-9 expression and activity, and thus reduced degradation of extracellular matrix and endothelial tight junction proteins. Importantly, the BBB- and neuro-protective effects of levofloxacin were abolished in A-FABP or MMP-9 knockout mice, suggesting that the therapeutic effects of levofloxacin highly depended on specific targeting of the A-FABP-MMP-9 axis. Overall, our study demonstrates that levofloxacin alleviates A-FABP-induced BBB disruption and neural tissue injury following cerebral I/R, and unveils its therapeutic potential for the treatment of ischemic stroke.

Faster Person Re-Identification: One-shot-Filter and Coarse-to-Fine Search.

Fast person re-identification (ReID) aims to search person images quickly and accurately. The main idea of recent fast ReID methods is the hashing algorithm, which learns compact binary codes and performs fast Hamming distance and counting sort. However, a very long code is needed for high accuracy (e.g. 2048), which compromises search speed. In this work, we introduce a new solution for fast ReID by formulating a novel Coarse-to-Fine (CtF) hashing code search strategy, which complementarily uses short and long codes, achieving both faster speed and better accuracy. It uses shorter codes to coarsely rank broad matching similarities and longer codes to refine only a few top candidates for more accurate instance ReID. Specifically, we design an All-in-One (AiO) module together with a Distance Threshold Optimization (DTO) algorithm. In AiO, we simultaneously learn and enhance multiple codes of different lengths in a single model. It learns multiple codes in a pyramid structure, and encourage shorter codes to mimic longer codes by self-distillation. DTO solves a complex threshold search problem by a simple optimization process, and the balance between accuracy and speed is easily controlled by a single parameter. It formulates the optimization target as a Fß score that can be optimised by Gaussian cumulative distribution functions. Besides, we find even short code (e.g. 32) still takes a long time under large-scale gallery due to the O(n) time complexity. To solve the problem, we propose a gallery-size-free latent-attributes-based One-Shot-Filter (OSF) strategy, that is always O(1) time complexity, to quickly filter major easy negative gallery images, Specifically, we design a Latent-Attribute-Learning (LAL) module supervised a Single-Direction-Metric (SDM) Loss. LAL is derived from principal component analysis (PCA) that keeps largest variance using shortest feature vector, meanwhile enabling batch and end-to-end learning. Every logit of a feature vector represents a meaningful attribute. SDM is carefully designed for fine-grained attribute supervision, outperforming common metrics such as Euclidean and Cosine metrics. Experimental results on 2 datasets show that CtF+OSF is not only 2% more accurate but also 5× faster than contemporary hashing ReID methods. Compared with non-hashing ReID methods, CtF is 50× faster with comparable accuracy. OSF further speeds CtF by 2× again and upto 10× in total with almost no accuracy drop.

Multi-kingdom gut microbiota analyses define bacterial-fungal interplay and microbial markers of pan-cancer immunotherapy across cohorts.

The effect of gut bacteria on the response to immune checkpoint inhibitors (ICIs) has been studied, but the relationship between fungi and ICI responses is not fully understood. Herein, 862 fecal metagenomes from 9 different cohorts were integrated for the identification of differentially abundant fungi and subsequent construction of random forest (RF) models to predict ICI responses. Fungal markers demonstrate excellent performance, with an average area under the curve (AUC) of 0.87. Their performance improves even further, reaching an average AUC of 0.89 when combined with bacterial markers. Higher enrichment of exhausted T cells is detected in responders, as predicted by fungal markers. Multi-kingdom network and functional analysis reveal that the fungus Schizosaccharomyces octosporus may ferment starch into short-chain fatty acids in responders. This study provides a fungal profile of the ICI response and the identification of multi-kingdom microbial markers with good performance that may improve the overall applicability of ICI therapy.

Peptide TK-HR from the Skin of Chinese Folk Medicine Frog Hoplobatrachus Rugulosus Accelerates Wound Healing via the Activation of the Neurokinin-1 Receptor.

Wound healing is a complex process and remains a considerable challenge in clinical trials due to the lack of ideal therapeutic drugs. Here, a new peptide TK-HR identified from the skin of the frog Hoplobatrachus rugulosus was tested for its ability to heal cutaneous wounds in mice. Topical application of TK-HR at doses of 50-200 µg/mL significantly accelerated wound closure without causing any adverse effects in the animals. In vitro and in vivo investigations proved the regulatory role of the peptide on neutrophils, macrophages, keratinocytes, and vein endothelial cells involved in the inflammatory, proliferative, and remodeling phases of wound healing. Notably, TK-HR activated the MAPK and TGF-ß-Smad signaling pathways by acting on NK1R in RAW264.7 cells and mice. The current work has identified that TK-HR is a potent wound healing regulator that can be applied for the treatment of wounds, including diabetic foot ulcers and infected wounds, in the future.

Microbiome and metabolome features in inflammatory bowel disease via multi-omics integration analyses across cohorts.

The perturbations of the gut microbiota and metabolites are closely associated with the progression of inflammatory bowel disease (IBD). However, inconsistent findings across studies impede a comprehensive understanding of their roles in IBD and their potential as reliable diagnostic biomarkers. To address this challenge, here we comprehensively analyze 9 metagenomic and 4 metabolomics cohorts of IBD from different populations. Through cross-cohort integrative analysis (CCIA), we identify a consistent characteristic of commensal gut microbiota. Especially, three bacteria, namely Asaccharobacter celatus, Gemmiger formicilis, and Erysipelatoclostridium ramosum, which are rarely reported in IBD. Metagenomic functional analysis reveals that essential gene of Two-component system pathway, linked to fecal calprotectin, are implicated in IBD. Metabolomics analysis shows 36 identified metabolites with significant differences, while the roles of these metabolites in IBD are still unknown. To further elucidate the relationship between gut microbiota and metabolites, we construct multi-omics biological correlation (MOBC) maps, which highlights gut microbial biotransformation deficiencies and significant alterations in aminoacyl-tRNA synthetases. Finally, we identify multi-omics biomarkers for IBD diagnosis, validated across multiple global cohorts (AUROC values ranging from 0.92 to 0.98). Our results offer valuable insights and a significant resource for developing mechanistic hypotheses on host-microbiome interactions in IBD.

Integrated transcriptomic and proteomic profiling reveals the key molecular signatures of brain endothelial reperfusion injury.

BACKGROUND: Reperfusion therapy after ischemic stroke often causes brain microvascular injury. However, the underlying mechanisms are unclear. METHODS: Transcriptomic and proteomic analyses were performed on human cerebral microvascular endothelial cells following oxygen-glucose deprivation (OGD) or OGD plus recovery (OGD/R) to identify molecules and signaling pathways dysregulated by reperfusion. Major findings were further validated in a mouse model of cerebral ischemia and reperfusion. RESULTS: Transcriptomic analysis identified 390 differentially expressed genes (DEGs) between the OGD/R and OGD group. Pathway analysis indicated that these genes were mostly associated with inflammation, including the TNF signaling pathway, TGF-ß signaling pathway, cytokine-cytokine receptor interaction, NOD-like receptor signaling pathway, and NF-κB signaling pathway. Proteomic analysis identified 201 differentially expressed proteins (DEPs), which were primarily associated with extracellular matrix destruction and remodeling, impairment of endothelial transport function, and inflammatory responses. Six genes (DUSP1, JUNB, NFKBIA, NR4A1, SERPINE1, and THBS1) were upregulated by OGD/R at both the mRNA and protein levels. In mice with cerebral ischemia and reperfusion, brain TNF signaling pathway was activated by reperfusion, and inhibiting TNF-α with adalimumab significantly attenuated reperfusion-induced brain endothelial inflammation. In addition, the protein level of THBS1 was substantially upregulated upon reperfusion in brain endothelial cells and the peri-endothelial area in mice receiving cerebral ischemia. CONCLUSION: Our study reveals the key molecular signatures of brain endothelial reperfusion injury and provides potential therapeutic targets for the treatment of brain microvascular injury after reperfusion therapy in ischemic stroke.

A new indole alkaloid from Cladosporium sp. SCSIO41205.

A new indole compound, N-hydroxy-N-(2-(1-hydroxy-2-methoxy-1H-indol-3-yl)ethyl acetamide (1), together with four known compounds, N-(2-(1H-indol-3-yl)ethylacetamide (2), N-acetylamicoumacin C (3), N-(2-phenylethyl)acetamide (4), and (2 R,3S)-1-(4-hydroxyphenyl)butane-2,3-diol (5) were isolated from Cladosporium sp. SCSIO41205. Their structures were established by detailed analysis of the NMR and HR-ESI-MS data.

Portable rotary PCR system for real-time detection of Pseudomonas aeruginosa in milk.

The rapid quantitative detection of Pseudomonas aeruginosa in milk is of great significance to food safety. Quantitative real-time polymerase chain reaction (qPCR) technology is a good choice to meet this requirement. A good qPCR system should show the advantages of being low cost, having low-power consumption, having potential for miniaturization and be portable. However, most of the time-domain-based qPCR systems reported to date do not meet these requirements. In this study, we propose a novel real-time rotary PCR reaction system (RRP) that meets all the abovementioned specifications, and contains four modules: a heating control module, a disposable PCR capillary tube, a mechanical control module, and a photoelectric detection module. The volume of our homemade-PCR capillary tube is only 3 µL. The total manufacturing cost is cheaper than $200, and the capillary tube is about 1.4 cents. The size parameter of the RRP is less than 300 mm × 150 mm × 150 mm, using low mobile power sources to operate. All the features mean that the RRP meets the advantages of low sample volumes, enhanced thermal conductivity and being portable. Through conducting the experimental quantitative detection of Pseudomonas aeruginosa in milk and theoretical simulations by COMSOL, we prove the feasibility of this rotary PCR real-time detection system, which has broad application prospects in the rapid detection of bacteria and food safety.

Comparison of the clinical efficacy of three cannulated screws with parallel distribution and inverted triangular distribution in the treatment of femoral neck fractures in the elderly.

The aim of the present study was to investigate the clinical efficacy of three cannulated screws with parallel distribution in comparison with the 'gold standard' of inverting three cannulated screws with triangular distribution, in the treatment of femoral neck fractures in the elderly. A total of 106 elderly patients with femoral neck fractures treated at the Department of Orthopedics of the First Affiliated Hospital of Nanjing Medical University (Jiangsu Provincial Hospital) from October 2018 to March 2020 were retrospectively analyzed and divided into groups A and B. Group A consisted of 51 patients with a mean age of 73.3±6.8 years; and group B consisted of 55 patients with a mean age of 74.5±7.3 years. Group A was treated with closed reduction + inverted triangular distribution of three cannulated screws, while group B was treated with closed reduction + parallel distribution of three cannulated screws, and the general surgical conditions, including fracture reduction quality, fracture healing, incidence of avascular necrosis of the femoral head, and functional recovery scale (FRS) score of hip joint function were assessed in both groups. All patients were followed up for an average of 14.8 months. Compared with group A, group B had significant advantages in operation time, number of times intraoperative fluoroscopy was performed, number of intraoperative guide wire adjustments, and proportion of postoperative referrals to the intensive care unit (P<0.05). There were no significant differences in fracture reduction quality, fracture healing, incidence of avascular necrosis of the femoral head, and FRS score of hip joint function between groups A and B (P>0.05). For elderly patients with femoral neck fractures, distributing three cannulated screws in parallel after closed reduction achieved similar clinical efficacy to 'gold standard' inverted triangular distribution, and had obvious advantages in operation time, with significantly reduced surgical difficulty. This procedure is therefore deemed worthy of promotion and clinical application in the primary hospitals of China.

Commensal bacteria promote azathioprine therapy failure in inflammatory bowel disease via decreasing 6-mercaptopurine bioavailability.

Azathioprine (AZA) therapy failure, though not the primary cause, contributes to disease relapse and progression in inflammatory bowel disease (IBD). However, the role of gut microbiota in AZA therapy failure remains poorly understood. We found a high prevalence of Blautia wexlerae in patients with IBD with AZA therapy failure, associated with shorter disease flare survival time. Colonization of B. wexlerae increased inflammatory macrophages and compromised AZA's therapeutic efficacy in mice with intestinal colitis. B. wexlerae colonization reduced 6-mercaptopurine (6-MP) bioavailability by enhancing selenium-dependent xanthine dehydrogenase (sd-XDH) activity. The enzyme sd-XDH converts 6-MP into its inactive metabolite, 6-thioxanthine (6-TX), thereby impairing its ability to inhibit inflammation in mice. Supplementation with Bacillus (B.) subtilis enriched in hypoxanthine phosphoribosyltransferase (HPRT) effectively mitigated B. wexlerae-induced AZA treatment failure in mice with intestinal colitis. These findings emphasize the need for tailored management strategies based on B. wexlerae levels in patients with IBD.