The Expression of Toll-like receptors in eutopic and ectopic endometrium and its implication in the inflammatory pathogenesis of adenomyosis

Prevalence and risk factors for chronic endometritis in patients with adenomyosis and infertility: a retrospective cohort study

BACKGROUND

To explore the incidence of chronic endometritis (CE) in patients with infertility and different forms of adenomyosis and analyze potential high-risk factors for infection.

METHODS

This retrospective cohort study included 154 patients with infertility in the Liuzhou Maternity and Child Healthcare Hospital. Among them, 77 patients with adenomyosis were divided into four subgroups based on magnetic resonance imaging (MRI): internal, exterior, intramural, and full-thickness. Meanwhile, 77 patients did not have adenomyosis. Hysteroscopy and endometrial biopsy were performed in the proliferative phase. The main outcome measures were the morphology of the endometrium, syndecan-1 (CD138) immunohistochemical staining, clinical characteristics, and prevalence of CE in the adenomyosis subgroups.

RESULTS

In comparison to the non-adenomyosis group, the adenomyosis group had significantly higher body mass index (BMI) and CA125 levels. The menstrual cycle in the adenomyosis group was significantly shorter, and menarche was significantly earlier. In comparison to the non-adenomyosis group, the adenomyosis group had a significantly higher diagnostic rate of CE (75.3% vs. 46.8% according to hysteroscopy and 74.0% vs. 33.8% according to histopathology, both with p < .050). The incidence of CE was significantly lower in patients with internal adenomyosis when compared with the other three subgroups. Increased BMI contributed to a higher risk of CE.

CONCLUSIONS

The prevalence of CE was significantly higher in patients with adenomyosis and infertility. The differences in the incidence of CE are closely associated with the classification of adenomyosis. When patients with infertility are diagnosed with adenomyosis, it is recommended to identify the subtype and screen for endometritis.

Cytotoxic T Lymphocytes, Tc17 Cells, Th1 Cells, and ThGM Cells are Increased in the Blood and Ectopic Endometrium of Patients With Adenomyosis

PROBLEM

Adenomyosis (AM) is associated with immune response and inflammation. However, the role of T cell subsets in AM development has not been thoroughly understood.

METHOD OF STUDY

Patients with focal or diffuse AM were recruited. Serum cytokines were quantified by enzyme-linked immunosorbent assay (ELISA). Different T cell subsets in the blood and ectopic endometrium were determined by flow cytometry.

RESULTS

Serum interleukin-6 (IL-6) and macrophage-colony-stimulating factor (GM-CSF) were increased in patients with focal or diffuse AM before focused ultrasound ablation surgery (FUAS), but not after FUAS. Compared with the healthy control, the frequencies of CD8+ interferon-gamma (IFN-γ)-expressing cytotoxic T lymphocytes (CTLs), interleukin-17A (IL-17A)-expressing Tc17 cells, CD4+ T helper 1 (Th1) cells, and GM-CSF-expressing T helper (ThGM) cells were up-regulated in the blood of patients with AM, especially those with diffuse AM. However, these changes were eradicated after FUAS. Meanwhile, the frequencies of these T cell subsets were positively correlated with the CA-125 level. Furthermore, these T cell subsets were also increased in ectopic endometrium.

CONCLUSIONS

Our study delineates for the first time the presence of CTLs, Tc17 cells, Th1, and ThGM cells in the blood and ectopic endometrium in AM. The results imply that T cell response might impact AM development.

mtDNA regulates cGAS-STING signaling pathway in adenomyosis

In various hyperproliferative disorders, damaged mitochondria can release mitochondrial DNA (mtDNA) into the cytoplasm, activating the cGAS-STING signaling pathway and subsequent immune imbalances. Our previous research has demonstrated that hypoxia plays a role in the development of adenomyosis (AM) by inducing mitochondrial dysfunction. However, the precise involvement of the cGAS-STING signaling pathway and mtDNA in AM remains unclear. Therefore, this study aims to investigate the relationship between mtDNA secretion, changes in the cGAS-STING signaling pathway, and the abnormal cellular proliferation observed in AM. We found the cGAS, STING, TBK1, p-TBK1, IRF3, and p-IRF3 proteins levels were significantly elevated in the tissues of patients with AM compared to the control group. Additionally, there was an increase in the expression of the pro-inflammatory cytokines IL-6 and IFN-α in the AM tissues. Hypoxia-induced an increase in the proliferation and migration abilities of endometrial stromal cells (ESCs), accompanied by the activation of the cGAS-STING signaling pathway and elevated levels of IFN-α. Furthermore, hypoxia promoted the leakage of mtDNA into the cytoplasm in AM ESCs, and the deletion of mtDNA reduced the activation of the cGAS-STING pathway. Moreover, knockdown of the STING gene inhibited the expression of TBK1, p-TBK1, IRF3, and p-IRF3 and suppressed the secretion of the inflammatory cytokines IL-6 and IFN-α. Furthermore, the migration and invasion abilities of AM ESCs were significantly diminished after STING knockdown. These findings provide valuable insights into the role of mtDNA release and the cGAS-STING signaling pathway in the pathogenesis of AM.

Exosomes: potential diagnostic markers and drug carriers for adenomyosis

Adenomyosis is a common benign gynecological disorder and an important factor leading to infertility in fertile women. Adenomyosis can cause deep lesions and is persistent and refractory in nature due to its tumor-like biological characteristics, such as the ability to implant, adhere, and invade. The pathogenesis of adenomyosis is currently unclear. Therefore, new therapeutic approaches are urgently required. Exosomes are nanoscale vesicles secreted by cells that carry proteins, genetic materials and other biologically active components. Exosomes play an important role in maintaining tissue homeostasis and regulating immune responses and metabolism. A growing body of work has shown that exosomes and their contents are key to the development and progression of adenomyosis. This review discusses the current research progress, future prospects and challenges in this emerging therapeutic tool by providing an overview of the changes in the adenomyosis uterine microenvironment and the biogenesis and functions of exosomes, with particular emphasis on the role of exosomes and their contents in the regulation of cell migration, proliferation, fibrosis formation, neovascularization, and inflammatory responses in adenomyosis.

Characterising the immune cell phenotype of ectopic adenomyosis lesions compared with eutopic endometrium: A systematic review

Inflammation is implicated in the symptomatology and the pathogenesis of adenomyosis. Injury at the endo-myometrial interface causes inflammation and may facilitate the invasion of endometrium into the myometrium, forming adenomyosis lesions. Their presence causes local inflammation, resulting in heavy menstrual bleeding, chronic pelvic pain, and subfertility. Immunological differences have been described in the eutopic endometrium from women with adenomyosis compared to healthy endometrium, and differences are also expected in the adenomyotic lesions compared with the correctly sited eutopic endometrium. This systematic review retrieved relevant articles from three databases with additional manual citation chaining from inception to 24th October 2022. Twenty-two eligible studies were selected in accordance with PRISMA guidelines. Risk of bias assessments were performed, and the findings presented thematically. Ectopic endometrial stroma contained an increased density of macrophages compared with eutopic endometrium in adenomyosis. This was associated with an increase in pro-inflammatory cytokines (IL-6, IL-8, ILβ-1, C-X-C Motif Chemokine Receptor 1(CXCR1), Monocyte Chemoattractant Protein-1 (MCP-1)), and an imbalance of anti-inflammatory cytokines (IL-22, IL-37). Cells in ectopic lesions also contained a higher levels of toll-like receptors and immune-mediated enzymes. However, the studies were heterogeneous, with inconsistent reporting of immune cell density within epithelial or stromal compartments, and inclusion of samples from different menstrual cycle phases in the same group for analysis. A detailed understanding of the immune cell phenotypes present in eutopic and ectopic endometrium in adenomyosis and associated dysregulated inflammatory processes will provide further insight into the pathogenesis, to enable identification of fertility-sparing treatments as an alternative to hysterectomy.

Endometrial Inflammation and Impaired Spontaneous Decidualization: Insights into the Pathogenesis of Adenomyosis

Adenomyosis is an estrogen-dependent gynecologic disease characterized by the myometrial invasion of the endometrial tissue. This review summarized the current understanding and recent findings on the pathophysiology of adenomyosis, focusing on repeated menstruation, persistent inflammation, and impaired spontaneous decidualization. A literature search was performed in the PubMed and Google Scholar databases from inception to 30 April 2022. Thirty-one full-text articles met the eligibility criteria. Repeated episodes of physiological events (i.e., endometrial shedding, damage, proliferation, differentiation, repair, and regeneration) during the menstrual cycle are associated with inflammation, angiogenesis, and immune processes. The decidualization process in humans is driven by the rise in progesterone levels, independently of pregnancy (i.e., spontaneous decidualization). Adenomyotic cells produce angiogenic and fibrogenic factors with the downregulation of decidualization-associated molecules. This decidualization dysfunction and persistent inflammation are closely related to the pathogenesis of adenomyosis. Recently, it has been found that the reproductive tract microbiota composition and function in women with adenomyosis differ from those without. An increase in opportunistic pathogens and a decrease in beneficial commensals may promote impaired defense mechanisms against inflammation and predispose women to uncontrolled endometrial inflammation. However, currently, there is no direct evidence that adenomyosis is linked to pre-existing inflammation and impaired spontaneous decidualization. Overall, persistent inflammation, impaired spontaneous decidualization, and microbiota dysbiosis (i.e., an imbalance in the composition and function of endometrial microbiota) may be involved in the pathophysiology of adenomyosis.

Pattern-recognition receptors in endometriosis: A narrative review

Endometriosis is closely associated with ectopic focal inflammation and immunosuppressive microenvironment. Multiple types of pattern recognition receptors (PRRs) are present in the innate immune system, which are able to detect pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs) in both intracellular and external environments. However, the exact role of PRRs in endometriosis and the underlying molecular mechanism are unclear. PRRs are necessary for the innate immune system to identify and destroy invasive foreign infectious agents. Mammals mainly have two types of microbial recognition systems. The first one consists of the membrane-bound receptors, such as toll-like receptors (TLRs), which recognize extracellular microorganisms and activate intracellular signals to stimulate immune responses. The second one consists of the intracellular PRRs, including nod-like receptors (NLRs) and antiviral proteins retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated gene 5 (MDA-5) with helix enzyme domain. In this review, we mainly focus on the key role of PRRs in the pathological processes associated with endometriosis. PRRs recognize PAMPs and can distinguish pathogenic microorganisms from self, triggering receptor ligand reaction followed by the stimulation of host immune response. Activated immune response promotes the transmission of microbial infection signals to the cells. As endometriosis is characterized by dysregulated inflammation and immune response, PRRs may potentially be involved in the activation of endometriosis-associated inflammation and immune disorders. Toll-like receptor 2 (TLR2), toll-like receptor 3 (TLR3), toll-like receptor 4 (TLR4), nod-like receptor family caspase activation and recruitment domain (CARD) domain containing 5 (NLRC5), nod-like receptor family pyrin domain containing 3 (NLRP3), and c-type lectin receptors (CLRs) play essential roles in endometriosis development by regulating immune and inflammatory responses. Absent in melanoma 2 (AIM2)-like receptors (ALRs) and retinoic acid-inducible gene I-like receptors (RLRs) may be involved in the activation of endometriosis-associated immune and inflammation disorders. PRRs, especially TLRs, may serve as potential therapeutic targets for alleviating pain in endometriosis patients. PRRs and their ligands interact with the innate immune system to enhance inflammation in the stromal cells during endometriosis. Thus, targeting PRRs and their new synthetic ligands may provide new therapeutic options for treating endometriosis.

Mechanism Study of Cinnamomi Ramulus and Paris polyphylla Sm. Drug Pair in the Treatment of Adenomyosis by Network Pharmacology and Experimental Validation

Objective. To explore the molecular mechanism of the Cinnamomi ramulus and Paris polyphylla Sm. (C-P) drug pair in the treatment of adenomyosis (AM) based on network pharmacology and animal experiments. Methods. Via a network pharmacology strategy, a drug-component-target-disease network (D-C-T-D) and protein–protein interaction (PPI) network were constructed to explore the core components and key targets of C-P drug pair therapy for AM, and the core components and key targets were verified by molecular docking. Based on the results of network pharmacology, animal experiments were performed for further verification. The therapeutic effect of the C-P drug pair on uterine ectopic lesions was evaluated in a constructed AM rat model. Results. A total of 30 components and 45 corresponding targets of C-P in the treatment of AM were obtained through network pharmacology. In the D-C-T-D network and PPI network, 5 core components and 10 key targets were identified. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that the PI3K signaling pathway was the most significantly enriched nontumor pathway. Molecular docking showed that most of the core components and key targets docked completely. Animal experiments showed that the C-P drug pair significantly ameliorated the pathological changes of endometriotic lesions in AM model rats and inhibited PI3K and Akt gene expression, and PI3K and Akt protein phosphorylation. In addition, treatment with the C-P drug pair promoted AM cell apoptosis; upregulated the protein expression of Bax, Caspase-3, and cleaved Caspase-9; and restrained Bcl-2 expression. Conclusions. We propose that the pharmacological mechanism of the C-P drug pair in the treatment of AM is related to inhibition of the PI3K/Akt pathway and promotion of apoptosis in AM ectopic lesions.

The Role of Abnormal Uterine Junction Zone in the Occurrence and Development of Adenomyosis

Adenomyosis is a benign disease with a malignant behavior, bothering a lot of women at reproductive age who suffer from increased menstruation, prolonged menstruation, progressive dysmenorrhea, and infertility. At present, there is no effective treatment for adenomyosis. It seriously affects the life quality of these patients. However, the pathogenesis of adenomyosis is not yet clear. Recently, uterus junctional zone, defined as the inner 1/3 of myometrium between endometrium and myometrium, has gained broad attention. As is reported, the structure and function disorder of uterus junctional zone may play an important part in the occurrence and development of adenomyosis. In this issue, the present study generally reviews the role of uterine junction zone and the related mechanisms involved in adenomyosis, such as the local micro-damage, the formation of inflammatory and hypoxic microenvironment, changes of cytokines, and abnormalities of miRNA as well as signal pathways. It will provide new insights and potential therapeutic target strategies for clinical strategies in the management of adenomyosis.

Role of inflammation in benign gynecologic disorders: from pathogenesis to novel therapies†

Emerging evidence supports the notion that inflammation fosters the development of common benign gynecologic disorders, including uterine leiomyoma, endometriosis, and adenomyosis. Numerous cytokines, chemokines, and growth and transcription factors have indisputable roles in the establishment and maintenance of benign gynecologic disorders by initiating complex cascades that promote proliferation, angiogenesis, and lesion progression. The interaction between inflammation and benign gynecologic disorders is orchestrated by a plethora of factors, including sex steroids, genetics, epigenetics, extracellular matrix, stem cells, cardiometabolic risk factors, diet, vitamin D, and the immune system. The role of inflammation in these disorders is not limited to local pathobiology but also extends to involve clinical sequelae that range from those confined to the reproductive tract, such as infertility and gynecologic malignancies, to systemic complications such as cardiovascular disease. Enhanced understanding of the intricate mechanisms of this association will introduce us to unvisited pathophysiological perspectives and guide future diagnostic and therapeutic implications aimed at reducing the burden of these disorders. Utilization of inflammatory markers, microRNA, and molecular imaging as diagnostic adjuncts may be valuable, noninvasive techniques for prompt detection of benign gynecologic disorders. Further, use of novel as well as previously established therapeutics, such as immunomodulators, hormonal treatments, cardiometabolic medications, and cyclooxygenase-2 and NF-κB inhibitors, can target inflammatory pathways involved in their pathogenesis. In this comprehensive review, we aim to dissect the existing literature on the role of inflammation in benign gynecologic disorders, including the proposed underlying mechanisms and complex interactions, its contribution to clinical sequelae, and the clinical implications this role entails.

Evaluation of Toll-like receptor 3 (TLR3) signaling pathway genes and its genetic polymorphisms in ectopic and eutopic endometrium of women with endometriosis

OBJECTIVE

Toll-like receptors (TLRs, as members of the innate immune system) are expressed in the human endometrium and their aberrant regulation and expression are involved in the pathogenesis of endometrial diseases. This study is aimed at evaluation of TLR3 signaling pathway genes and its genetic changes in endometriosis patients.

MATERIALS AND METHODS

Blood samples were collected from 83 endometriosis patients and 93 healthy fertile women and PCR was performed in blood-derived DNA for detection of SNP of TLR3. Also, ectopic (EC) and eutopic (EU) endometrial biopsies were obtained from endometriosis patients (n = 20), as well as endometrium from healthy women (n = 16, CE). Q-PCR was performed for determination of mRNA expression level of TLR3 signaling pathway genes (TLR3, TICAM, NF-kB1A, CXCL10, IRF3, IFN-B1, IL-6 and IL-8). Also, serum protein levels of TLR3, IFN-β, IL-6 and IL-8 were determined using ELISA.

RESULTS

The mRNA expression levels of TLR3, NF-kB1A, IFN-B1, IRF3, TICAM1, IL-6 and IL-8 were significantly higher in EU compared to ectopic ones and also compared to CE. SNPs frequency (rs3775291 and rs3775290) was not significantly different between patients and controls. Serum protein levels of TLR3, IFN-β, IL-6 and IL-8 were significantly increased in endometriosis patients.

CONCLUSION

Significant changes were observed in the expression of IL-6 and IL-8 cytokines and other genes in TLR3 cascade in diseased EU, demonstrating that EU similarly to EC is in an intensive inflammatory state. These fundamental alterations in the concept of immune response in EU may lead to its activation, escapes from apoptosis, and displaced implantation of the endometrium.

Proteomic Analysis of Uterine Tissues During Peri-Implantation Period in Mice with Experimentally Induced Adenomyosis that Treated with anti-Ngf: Implications for Cell-Cell Adhesion and Metabolic Processes

Nerve growth factor (NGF) has been verified to be expressed with higher level in adenomyosis uteri, and its neutralizing antibody has a strong inhibitory influence on inflammation. The present study aimed to explore the effect of anti-NGF on the expression of proteins in uteri of mice-induced adenomyosis and assessed its potential role in improving pregnancy rate. In this study, we established a mouse model of adenomyosis and administrated NGF-neutralizing antibody into mice. The mass spectrometry (MS) analysis of the uteri during the implantation window was performed to explore the essential proteins participating in therapy. Besides, embryos of healthy mice were transferred into the uteri to assess the implantation rate. The results of MS analysis demonstrated that 119 proteins were changed in the adenomyosis group compared with control group, and 126 proteins were differentially expressed in the anti-NGF group compared with the adenomyosis group (fold change > 1.5, P < 0.05. After performing cluster analysis using Mfuzz package, we found that a group of proteins participated in cell-cell adhesion and metabolic processes, which were attenuated in the adenomyosis group, while those were successfully recovered by anti-NGF treatment. Western blotting confirmed that the expression levels of integrin alpha-1 (ITGA1), integrin beta-1 (ITGB1), laminin subunit gamma-1 (LAMC1), and creatine kinase M-type (CKM) were decreased in adenomyosis group, whereas those levels were elevated after anti-NGF treatment. Embryo implantation rate in the adenomyosis group was significantly decreased compared with that in the control group (2.31% vs. 26.15%, P < 0.001) and anti-NGF treatment slightly enhanced the embryo implantation rate in mice with experimentally induced adenomyosis (9.23% vs. 2.31%, P = 0.017). Our results revealed that anti-NGF therapy can improve fertility of mice with experimentally induced adenomyosis, possibly through promoting integrin-related proteins.

Distinct expression patterns of TLR transcripts in human oocytes and granulosa cells from primordial and primary follicles

Ovulation has long been regarded as a process resembling an inflammatory response. Previously, luteinizing hormone (LH) was shown to induce Toll-like receptor 2 (TLR2) and TLR4 in granulosa cells from preovulatory hormone-dependent follicles. However, whether this could already initiate before the hormone-dependent phase is currently unknown. The aim of this study was to investigate TLR genes in human oocytes and granulosa cells from primordial and primary ovarian follicles during the hormone-independent phase. A class-comparison study of existing oocyte and granulosa cell RNA sequencing transcriptomes from primordial (n = 539 follicles) and primary (n = 261) follicles collected from three patients was examined. This revealed a distinct expression pattern of TLR3, TLR4 and TLR5 transcripts. Interestingly, the TLR3 protein was differentially detected in both the oocyte and the granulosa cells in primordial and primary follicles, suggesting that TLR3 is maternally contributed both as mRNA and protein. Intracellularly, the compartmentalized TLR3 dot-like staining in the intersection between the oocyte and the surrounding primordial granulosa cells. The TLR4 protein was detected in both primordial and primary follicles, with a notable staining in the granulosa cells. We functionally challenged ovaries in vitro, by polyinosinic:polycytidylic acid (poly I:C) and LPS, known to activate TLR3 and TLR4, respectively, and found a tendency for increased IL-6 production, which was particular evident in the LPS-treated group. Based on the expression of TLRs, it is notably that human primordial and primary follicles express genes that would allow them to respond to innate immune proteins and cytokines during follicle activation.

RhoA/ROCK/ARHGAP26 signaling in the eutopic and ectopic endometrium is involved in clinical characteristics of adenomyosis

OBJECTIVE

This study aimed to investigate RhoA, RhoA-associated coiled-coil containing protein kinase (ROCK) 1, ROCK2, and Rho GTPase-activating protein 26 (ARHGAP26) expression in the eutopic endometrium (EU) and ectopic endometrium (EC), and examine their relationships with the clinical characteristics of adenomyosis.

METHODS

Twenty patients with adenomyosis who underwent laparoscopy were recruited. Protein and mRNA expression of RhoA, ROCK1, ROCK2, and ARHGAP26 in EU and EC of patients with adenomyosis and in control endometrium without adenomyosis (CE) was detected.

RESULTS

ROCK1, ROCK2, and RhoA mRNA expression in EU was significantly higher than that in CE, and was highest in EC. ARHGAP26 mRNA expression in EC and EU was significantly lower than that in CE. ROCK1, ROCK2, and RhoA protein expression in EC and EU was significantly higher than that in CE. ARHGAP26 protein expression in EC and EU was significantly lower than that in CE. ROCK1, ROCK2, and RhoA gene and protein expression was positively associated and ARHGAP26 was negatively associated with the severity of menorrhagia and menstrual capacity in adenomyosis.

CONCLUSIONS

RhoA, ROCK1, and ROCK2 expression is upregulated, and ARHGAP26 expression is downregulated in adenomyosis. The RhoA/ROCK-mediated signaling pathway is associated with dysmenorrhea and menstrual capacity in adenomyosis.

Association between the HMGB1/TLR4 signaling pathway and the clinicopathological features of ovarian cancer

In the present study, the expression levels of high‑mobility group protein B1 (HMGB1), Toll‑like receptor 4 (TLR4), nuclear factor (NF)‑κB and tumor necrosis factor (TNF)‑α in malignant epithelial ovarian cancer (MEOC) were investigated in regards to several clinicopathological characteristics. A total of 20 patients with MEOC who underwent surgery were recruited in the present study. The mRNA and protein expression of HMGB1, TLR4, NF‑κB and TNF‑α was determined in patients with MEOC and compared with expression levels in 20 patients diagnosed with benign ovarian cysts (BOC). It was demonstrated that the mRNA and protein expression of HMGB1, TLR4, NF‑κB and TNF‑α in MEOC was significantly increased, compared with the BOC group (P<0.01). The gene and protein expression of HMGB1, TLR4, NF‑κB and TNF‑α was significantly increased in the advanced tumor stage and poorly differentiated group (P<0.01). The present study suggested that the HMGB1/TLR4 signaling pathway was overactive in MEOC, and was associated with MEOC tumor cell proliferation, invasion and metastasis. Furthermore, this may have been mediated via NF‑κB signaling.

Outer Membrane Vesicles From Probiotic and Commensal Escherichia coli Activate NOD1-Mediated Immune Responses in Intestinal Epithelial Cells

Gut microbiota plays a critical role in maintaining human intestinal homeostasis and host health. Bacterial extracellular vesicles are key players in bacteria-host communication, as they allow delivery of effector molecules into the host cells. Outer membrane vesicles (OMVs) released by Gram-negative bacteria carry many ligands of pattern recognition receptors that are key components of innate immunity. NOD1 and NOD2 cytosolic receptors specifically recognize peptidoglycans present within the bacterial cell wall. These intracellular immune receptors are essential in host defense against bacterial infections and in the regulation of inflammatory responses. Recent contributions show that NODs are also fundamental to maintain intestinal homeostasis and microbiota balance. Peptidoglycan from non-invasive pathogens is delivered to cytosolic NODs through OMVs, which are internalized via endocytosis. Whether this pathway could be used by microbiota to activate NOD receptors remains unexplored. Here, we report that OMVs isolated from the probiotic Escherichia coli Nissle 1917 and the commensal ECOR12 activate NOD1 signaling pathways in intestinal epithelial cells. NOD1 silencing and RIP2 inhibition significantly abolished OMV-mediated activation of NF-κB and subsequent IL-6 and IL-8 expression. Confocal fluorescence microscopy analysis confirmed that endocytosed OMVs colocalize with NOD1, trigger the formation of NOD1 aggregates, and promote NOD1 association with early endosomes. This study shows for the first time the activation of NOD1-signaling pathways by extracellular vesicles released by gut microbiota.