Project description:Intestinal Foxp3+ regulatory T cell (Treg) subsets are crucial players for tolerance towards microbiota-derived and food-borne antigens, and compelling evidence suggests that intestinal microbiota modulate their differentiation and maintenance. Selected bacterial species and microbiota-derived metabolites such as short-chain fatty acids (SCFAs) have been reported to foster Treg homeostasis in the intestinal lamina propria. Furthermore, gut-draining mesenteric lymph nodes (mLNs) are particularly efficient sites of de novo Treg induction, and we could previously show that mLN stromal cells contribute to this process. Yet, it is not fully elucidated which direct role microbiota and their metabolites play for the early stages of de novo Treg induction and in shaping the Treg transcriptome already during the initial priming within mLNs. Here, we show that neither dysbiotic microbiota nor dietary SCFA supplementation impact de novo induction of Foxp3+ Tregs within mLNs. Even mice housed under germ-free (GF) conditions displayed equivalent frequencies of de novo induced Foxp3+ Tregs within mLNs. Further dissection of the accessible chromatin and transcriptome revealed that microbiota indeed have a limited impact on fostering the establishment of peripherally induced Tregs and do not contribute to the initialization of the epigenetic landscape for an extensive Treg signature. Viewed as a whole, our data suggest that microbiota are dispensable for the early stages of de novo Treg induction within mLNs, while being required to foster further Treg differentiation and homeostasis at later stages within the intestinal lamina propria.
Project description:The IL-33 receptor ST2 is differentially expressed by colonic lamina propria Treg cells Microarray of sort-purified Foxp3+ Treg cells from colonic lamina propria over mesenteric lymph node
Project description:Secreted extracellular vesicles are known to influence the tumor microenvironment and promote metastasis. In this work, we have analyzed the involvement of extracellular vesicles in the establishment of lymph node pre-metastatic niches by melanoma cells. We found that small extracellular vesicles (sEVs) derived from highly metastatic melanoma cell lines spread broadly through the lymphatic system and were taken up by lymphatic endothelial cells, reinforcing lymph node metastasis. Melanoma-derived sEVs induce lymphangiogenesis, a hallmark of pre-metastatic niche formation, in vitro and in lymphoreporter mice in vivo. We found that neural growth factor receptor (NGFR) is secreted in melanoma-derived small extracellular vesicles and shuttled to lymphatic endothelial cells, inducing lymphangiogenesis and tumor cell adhesion through the activation of ERK and NF-B pathways and ICAM1 expression. Importantly, ablation or inhibition of NGFR in sEVs reversed the lymphangiogenic phenotype, decreased melanoma lymph node metastasis and extended the survival. Importantly, analysis of NGFR expression in lymph node metastases and matched primary tumors shows that levels of MITF+NGFR+ lymph node metastatic cells are correlated with disease outcome. Our data support the idea that NGFR secreted in sEVs favors lymph node pre-metastatic niche formation and lymph node metastasis in melanoma
Project description:Secreted extracellular vesicles are known to influence the tumor microenvironment and promote metastasis. In this work, we have analyzed the involvement of extracellular vesicles in establishing the lymph node pre-metastatic niche by melanoma cells. We found that small extracellular vesicles (sEVs) derived from highly metastatic melanoma cell lines spread broadly through the lymphatic system and are taken up by lymphatic endothelial cells reinforcing lymph node metastasis. Melanoma-derived sEVs induce lymphangiogenesis, a hallmark of pre-metastatic niche formation, in vitro and in lymphoreporter mice in vivo. Analysis of involved factors demonstrated that the neural growth factor receptor (NGFR) is secreted in melanoma-derived small extracellular vesicles and shuttled to lymphatic endothelial cells inducing lymphangiogenesis and tumor cell adhesion through the activation of ERK and NF-B pathways and ICAM1 expression. Importantly, ablation or inhibition of NGFR in sEVs reversed the lymphangiogenic phenotype, decreased melanoma lymph node metastasis and extended mice survival. Importantly, analysis of NGFR expression in lymph node metastases and matched primary tumors shows that levels of MITF+NGFR+ lymph node metastatic cells are correlated with disease outcome. Our data support that NGFR is secreted in sEVs favoring lymph node pre-metastatic niche formation and lymph node metastasis in melanoma.
Project description:Intestinal regulatory T cells (Tregs) are fundamental in peripheral tolerance toward commensals and food-borne antigens. Accordingly, gut-draining mesenteric lymph nodes (mLNs) represent a site of efficient peripheral de novo Treg induction when compared to skin-draining peripheral LNs (pLNs), and we had recently shown that LN stromal cells substantially contribute to this process. Here, we aimed to unravel the underlying molecular mechanisms and generated immortalized fibroblastic reticular cell lines (iFRCs) from mLNs and pLNs, allowing unlimited investigation of this rare stromal cell subset. In line with our previous findings, mLN-iFRCs showed a higher Treg-inducing capacity when compared to pLN-iFRCs. RNA-seq analysis focusing on secreted molecules revealed a more tolerogenic phenotype of mLN- as compared to pLN-iFRCs. Remarkably, mLN-iFRCs produced substantial numbers of microvesicles (MVs) that carried elevated levels of TGF-β when compared to pLN-iFRC-derived MVs, and these novel players of intercellular communication were shown to be responsible for the tolerogenic properties of mLN-iFRCs. Thus, stromal cells originating from mLNs contribute to peripheral tolerance by fostering de novo Treg induction using TGF-β-carrying MVs. This finding provides novel insights into the subcellular/molecular mechanisms of de novo Treg induction and might serve as promising tool for future therapeutic applications to treat inflammatory disorders.
Project description:Gut-draining mesenteric lymph nodes (mLNs) play a key role in peripheral tolerance towards food and commensal antigens by providing an optimal microenvironment for efficient de novo induction of Foxp3+ regulatory T cells (Tregs). We recently identified mLN stromal cells as critical cellular players in this process and demonstrated that their tolerogenic properties are imprinted by microbiota. Here, we show that this imprinting process already takes place in the neonatal phase and renders the mLN stromal cell compartment resistant to inflammatory perturbations later in life. Utilizing LN transplantation, RNA-seq and single-cell RNA-seq allowed identification of stably imprinted expression signatures in mLN fibroblastic stromal cells. We dissected common stromal cell subsets across gut-draining mLNs and skin-draining LNs with location-specific immunomodulatory functions, such as subset-specific expression of Aldh1a2/3. Accordingly, mLN stromal cells shaped resident dendritic cells to attain high Treg-inducing capacity in a Bmp2-dependent manner. Thus, crosstalk between mLN stromal and resident dendritic cells provides a robust feedback mechanism for the maintenance of intestinal tolerance.
Project description:Gut-draining mesenteric lymph nodes (mLNs) play a key role in peripheral tolerance towards food and commensal antigens by providing an optimal microenvironment for efficient de novo induction of Foxp3+ regulatory T cells (Tregs). We recently identified mLN stromal cells as critical cellular players in this process and demonstrated that their tolerogenic properties are imprinted by microbiota. Here, we show that this imprinting process already takes place in the neonatal phase and renders the mLN stromal cell compartment resistant to inflammatory perturbations later in life. Utilizing LN transplantation, RNA-seq and single-cell RNA-seq allowed identification of stably imprinted expression signatures in mLN fibroblastic stromal cells. We dissected common stromal cell subsets across gut-draining mLNs and skin-draining LNs with location-specific immunomodulatory functions, such as subset-specific expression of Aldh1a2/3. Accordingly, mLN stromal cells shaped resident dendritic cells to attain high Treg-inducing capacity in a Bmp2-dependent manner. Thus, crosstalk between mLN stromal and resident dendritic cells provides a robust feedback mechanism for the maintenance of intestinal tolerance.
Project description:Gut-draining mesenteric lymph nodes (mLNs) play a key role in peripheral tolerance towards food and commensal antigens by providing an optimal microenvironment for efficient de novo induction of Foxp3+ regulatory T cells (Tregs). We recently identified mLN stromal cells as critical cellular players in this process and demonstrated that their tolerogenic properties are imprinted by microbiota. Here, we show that this imprinting process already takes place in the neonatal phase and renders the mLN stromal cell compartment resistant to inflammatory perturbations later in life. Utilizing LN transplantation, RNA-seq and single-cell RNA-seq allowed identification of stably imprinted expression signatures in mLN fibroblastic stromal cells. We dissected common stromal cell subsets across gut-draining mLNs and skin-draining LNs with location-specific immunomodulatory functions, such as subset-specific expression of Aldh1a2/3. Accordingly, mLN stromal cells shaped resident dendritic cells to attain high Treg-inducing capacity in a Bmp2-dependent manner. Thus, crosstalk between mLN stromal and resident dendritic cells provides a robust feedback mechanism for the maintenance of intestinal tolerance.
Project description:Gut-draining mesenteric lymph nodes (mLNs) play a key role in peripheral tolerance towards food and commensal antigens by providing an optimal microenvironment for efficient de novo induction of Foxp3+ regulatory T cells (Tregs). We recently identified mLN stromal cells as critical cellular players in this process and demonstrated that their tolerogenic properties are imprinted by microbiota. Here, we show that this imprinting process already takes place in the neonatal phase and renders the mLN stromal cell compartment resistant to inflammatory perturbations later in life. Utilizing LN transplantation, RNA-seq and single-cell RNA-seq allowed identification of stably imprinted expression signatures in mLN fibroblastic stromal cells. We dissected common stromal cell subsets across gut-draining mLNs and skin-draining LNs with location-specific immunomodulatory functions, such as subset-specific expression of Aldh1a2/3. Accordingly, mLN stromal cells shaped resident dendritic cells to attain high Treg-inducing capacity in a Bmp2-dependent manner. Thus, crosstalk between mLN stromal and resident dendritic cells provides a robust feedback mechanism for the maintenance of intestinal tolerance.