Colon Lymph Nodes Research Articles

Artificial intelligence-based automated determination in breast and colon cancer and distinction between atypical and typical mitosis using a cloud-based platform

Artificial intelligence (AI) technology in pathology has been utilized in many areas and requires supervised machine learning. Notably, the annotations that define the ground truth for the identification of different confusing process pathologies, vary from study to study. In this study, we present our findings in the detection of invasive breast cancer for the IHC/ISH assessment system, along with the automated analysis of each tissue layer, cancer type, etc. in colorectal specimens. Additionally, models for the detection of atypical and typical mitosis in several organs were developed using existing whole-slide image (WSI) sets from other AI projects. All H&E slides were scanned by different scanners with a resolution of 0.12–0.50 μm/pixel, and then uploaded to a cloud-based AI platform. Convolutional neural networks (CNN) training sets consisted of invasive carcinoma, atypical and typical mitosis, and colonic tissue elements (mucosa-epithelium, lamina propria, muscularis mucosa, submucosa, muscularis propria, subserosa, vessels, and lymph nodes). In total, 59 WSIs from 59 breast cases, 217 WSIs from 54 colon cases, and 28 WSIs from 23 different types of tumor cases with relatively higher amounts of mitosis were annotated for the training. The harmonic average of precision and sensitivity was scored as F1 by AI. The final AI models of the Breast Project showed an F1 score of 94.49% for Invasive carcinoma. The mitosis project showed F1 scores of 80.18%, 97.40%, and 97.68% for mitosis, atypical, and typical mitosis layers, respectively. Overall F1 scores for the current results of the colon project were 90.02% for invasive carcinoma, 94.81% for the submucosa layer, and 98.02% for vessels and lymph nodes. After the training and optimization of the AI models and validation of each model, external validators evaluated the results of the AI models via blind-reader tasks. The AI models developed in this study were able to identify tumor foci, distinguish in situ areas, define colonic layers, detect vessels and lymph nodes, and catch the difference between atypical and typical mitosis. All results were exported for integration into our in-house applications for breast cancer and AI model development for both whole-block and whole-slide image-based 3D imaging assessment.

Consensus tissue domain detection in spatial omics data using multiplex image labeling with regional morphology (MILWRM).

Spatially resolved molecular assays provide high dimensional genetic, transcriptomic, proteomic, and epigenetic information in situ and at various resolutions. Pairing these data across modalities with histological features enables powerful studies of tissue pathology in the context of an intact microenvironment and tissue structure. Increasing dimensions across molecular analytes and samples require new data science approaches to functionally annotate spatially resolved molecular data. A specific challenge is data-driven cross-sample domain detection that allows for analysis within and between consensus tissue compartments across high volumes of multiplex datasets stemming from tissue atlasing efforts. Here, we present MILWRM (multiplex image labeling with regional morphology)-a Python package for rapid, multi-scale tissue domain detection and annotation at the image- or spot-level. We demonstrate MILWRM's utility in identifying histologically distinct compartments in human colonic polyps, lymph nodes, mouse kidney, and mouse brain slices through spatially-informed clustering in two different spatial data modalities from different platforms. We used tissue domains detected in human colonic polyps to elucidate the molecular distinction between polyp subtypes, and explored the ability of MILWRM to identify anatomical regions of the brain tissue and their respective distinct molecular profiles.

Abstract B040: B cells facilitate lymph node colonization in pancreatic ductal adenocarcinoma

Abstract Pancreatic ductal adenocarcinoma (PDAC) carries a low survival rate. Several factors contribute to its dismal prognosis, including resistance to available therapies and high invasiveness. Lymph nodes act as an early systemic source of circulating malignant cells, allowing their dissemination to other organs early in disease progression. Lymphatic colonization is linked to worse prognosis, and a better understanding of mechanisms regulating lymph node metastasis is clinically needed. To study each step in the metastatic cascade to the lymph nodes, we have developed a mouse co-clinical model of resectable pancreatic cancer. This model mimics the frequency of human PDAC metastatic recurrence, on a similar time scale relative to the lifespans of mice and humans and allows us to investigate very early events in the metastatic cascade. In contrast to the established anti-tumor role of T cells, the role of B cells in cancer immunology is more complex. B cells are a predominant immune population in lymph nodes, but their role in relation to lymph node colonization has never been fully addressed. Using our model of PDAC spontaneous metastasis and a mouse model of B cell depletion, we showed that lymph node metastasis does not form in the absence of B cells. We demonstrated that B cells, but not secreted antibodies, are required for successful lymph node colonization. We also gained evidence that B cells are orchestrating a complex interplay between disseminated cancer cells and other immune cells in the draining lymph node. Particularly, T cells seem to be involved in preventing cancer cell from growing into macro-metastasis only in the absence of B cells. We are now investigating the mechanisms employed by B cells to facilitate this cellular network to facilitate lymph node colonization in PDAC. The ultimate outcome of our work will be the design of effective immune strategies to prevent and treat lymph node dissemination of such a deadly disease. Citation Format: Alice Bertocchi, Megan T Hoffman, Li Qiang, Massiel Morell, Lauren L Hsu, Michael L Dougan, Judith Agudo, Stephanie K Dougan. B cells facilitate lymph node colonization in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr B040.

Solute Transporter OCTN1/Slc22a4 Affects Disease Severity and Response to Infliximab in Experimental Colitis: Role of Gut Microbiota and Immune Modulation

Abstract Background Inflammatory bowel diseases are chronic disabling conditions with a complex and multifactorial etiology, still incompletely understood. OCTN1, an organic cation transporter, could have a role in modulating the inflammatory response, and some genetic polymorphisms of this molecule have been associated with increased risk of inflammatory bowel diseases. Until now, limited information exists on its potential in predicting/modulating patient’s response to therapies. The aim of this study was to evaluate the role of OCTN1 in modifying gut microbiota and mucosal immunity in response to infliximab therapy in murine colitis. Methods A dextran sodium sulphate model of colitis was used to assess the clinical efficacy of infliximab administered intravenously in ocnt1 gene knockout mice and their C57BL/6 controls. Stool, colon, and mesenteric lymph node samples were collected to evaluate differences in gut microbiota composition, histology, and T cell populations, respectively. Results Octn1 -/- influences the microbiota profile and is associated with a worse dysbiosis in mice with colitis. Infliximab treatment attenuates colitis-associated dysbiosis, with an increase of bacterial richness and evenness in both strains. In comparison with wild type, octn1-/- mice have milder disease and a higher baseline percentage of Treg, Tmemory, Th2 and Th17 cells. Conclusions Our data support the murine model to study OCTN1 genetic contribution to inflammatory bowel diseases. This could be the first step towards the recognition of this membrane transporter as a biomarker in inflammatory conditions and a predictor of response to therapies.

Fecal microbiota transplantation stimulates type 2 and tolerogenic immune responses in a mouse model

ObjectivesClostridioides difficile infection (CDI) is the leading hospital-acquired infection in North America. While previous work on fecal microbiota transplantation (FMT), a highly effective treatment for CDI, has focused on colonization resistance mounted against C. difficile by FMT-delivered commensals, the effects of FMT on host gene expression are relatively unexplored. This study aims to identify transcriptional changes associated with FMT, particularly changes associated with protective immune responses. MethodsGene expression was assessed on day 2 and day 7 after FMT in mice after antibiotic-induced dysbiosis. Flow cytometry was also performed on colon and mesenteric lymph nodes at day 7 to investigate changes in immune cell populations. ResultsFMT administration after antibiotic-induced dysbiosis successfully restored microbial alpha diversity to levels of donor mice by day 7 post-FMT. Bulk RNA sequencing of cecal tissue at day 2 identified immune genes, including both pro-inflammatory and Type 2 immune pathways as upregulated after FMT. RNA sequencing was repeated on day 7 post-FMT, and expression of these immune genes was decreased along with upregulation of genes associated with restoration of intestinal homeostasis. Immunoprofiling on day 7 identified increased colonic CD45+ immune cells that exhibited dampened Type 1 and heightened regulatory and Type 2 responses. These include an increased abundance of eosinophils, alternatively activated macrophages, Th2, and T regulatory cell populations. ConclusionThese results highlight the impact of FMT on host gene expression, providing evidence that FMT restores intestinal homeostasis after antibiotic treatment and facilitates tolerogenic and Type 2 immune responses.

Abstract A024: B cells facilitate lymph node colonization in pancreatic ductal adenocarcinoma

Abstract Pancreatic ductal adenocarcinoma (PDAC) has a low survival rate. Several factors contribute to its dismal prognosis, including resistance to available therapies and high invasiveness. Lymph nodes act as an early systemic source of circulating malignant cells in PDAC, allowing their dissemination to other organs early in disease progression. Lymphatic colonization is linked to worse prognosis. Therefore, a better understanding of mechanisms regulating lymph node metastasis is clinically needed. To study each step in the metastatic cascade to the lymph nodes, we have developed a mouse co-clinical model of resectable pancreatic cancer. This model consists of subcutaneous injection of highly metastatic pancreatic cancer cells, followed by surgical resection of the primary tumor. Following resection, mice spontaneously develop lymph nodes metastasis at a comparable frequency to human PDAC post-surgical recurrence, on a similar time scale relative to the lifespans of mice and humans. Expression of nuclear tdTomato allows detection of single cancer cells seeding the draining lymph nodes early in disease progression, even before metastases are histological detectable. Using this model, we are gaining insights into the first steps of metastatic seeding of lymph nodes, and have identified a pro-metastatic role for B cells. These findings will enhance our understanding of lymphatic colonization in PDAC and potentially inform immunotherapeutic interventions to disrupt the metastatic cascade. Citation Format: Alice Bertocchi, Megan T. Hoffman, Li Qiang, Lauren Hsu, Michael Dougan, Judith Agudo, Stephanie K. Dougan. B cells facilitate lymph node colonization in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr A024.

The Relationship Between the Resected Colon Length and the Number of Lymph Nodes in Colorectal Cancer: A Retrospective Cohort Study

Objective: The prognostic factors that are important for colorectal cancer are the pathological grade of the tumor and the existence of lymph node involvement. Currently, the curative treatment option is resection of the tumor with adequate length and margin along with complete dissection of lymph nodes draining the site of resection. Our study investigated into retrieving adequate lymph nodes for accurate staging as well as the relationship between lymph nodes and colon and rectum specimen length. Methods: This retrospective cross-sectional study examined the correlation between resected colon length and lymph node count in people with colorectal cancer diagnosed between January 2010 and June 2018. We defined a cutoff value for the segment length to be resected to allow adequate staging of the tumor. Furthermore, we examined the relationship between the resected segment lengths and survival. Results: Of the patients who were included in this study, 211 were men and 169 were women. The mean resected colon length was 26.47±17.09 cm and the mean dissected lymph node count was 29.05±20.84. There was a positive correlation between specimen length and total lymph node count as well as specimen length and the existence of reactive lymph nodes that were statistically significant (r=0.319, p=0.001; r=0.312, p=0.001, respectively). In our study, tumor localization was described in three regions: the right colon, left colon and rectum. The mean right colon region specimen length was 28.8±15.5 cm, while it was 22.0±11.0 cm for the left colon region, and 21.7±10.6 cm for the rectum region. The 5-year overall survival rate was 53.2%, whereas the 5-year disease-specific survival rate was 58.2%. Conclusion: The mean specimen length to achieve the cutoff value for adequate lymph node retrieval (least 12 lymph nodes) was 16 cm in our study (ROC curve, AUC=0.689±0.05, p=0.001). The resected colon length and the number of retrieved lymph nodes were positively correlated in our study. Based on this confirmation, a cutoff value of 16 cm was calculated to achieve an adequate segment length to be resected.

The lymphatic system favours survival of a unique T. brucei population.

Trypanosoma brucei colonize and multiply in the blood vasculature, as well as in various organs of the host's body. Lymph nodes have been previously shown to harbour large numbers of parasites, and the lymphatic system has been proposed as a key site that allows T. brucei distribution through, and colonization of the mammalian body. However, visualization of host-pathogen interactions in the lymphatic system has never captured dynamic events with high spatial and temporal resolution throughout infection. In our work, we used a mixture of tools including intravital microscopy and ex vivo imaging to study T. brucei distribution in 20 sets of lymph nodes. We demonstrate that lymph node colonization by T. brucei is different across lymph node sets, with the most heavily colonized being the draining lymph nodes of main tissue reservoirs: the gonadal white adipose tissue and pancreas. Moreover, we show that the lymphatic vasculature is a pivotal site for parasite dispersal, and altering this colonization by blocking LYVE-1 is detrimental for parasite survival. Additionally, parasites within the lymphatic vasculature have unique morphological and behavioural characteristics, different to those found in the blood, demonstrating that across both types of vasculature, these environments are physically separated. Finally, we demonstrate that the lymph nodes and the lymphatic vasculature undergo significant alterations during T. brucei infection, resulting in oedema throughout the host's body.

Abstract PR01: Lymph node colonization promotes distant tumor metastasis through the induction of tumor-specific immune tolerance

Abstract The majority of cancer-associated deaths result from distant organ metastasis, yet the mechanisms that enable this process remain poorly understood. Colonization of regional or distant lymph nodes (LNs) typically precedes the formation of distant organ metastases, yet it has been unclear whether LN metastasis plays a functional role in disease progression. LNs are major sites of anti-tumor lymphocyte education, including in the context of immunotherapy, yet LN metastasis frequently correlates with further disease progression. Here, we find that LN metastasis represents a critical step in tumor progression through the capacity of such metastases to induce tumor-specific immune tolerance in a manner that promotes further dissemination of tumors to distant organs. Using an in vivo passaging approach, we generated 300 unique cell lines exhibiting varying degrees of LN metastatic capacity. We show that the presence of these LN metastases enables distant organ seeding of metastases in a manner that the parental tumor cannot, and this effect is eliminated in mice lacking an adaptive immune response. Furthermore, this promotion of distant seeding by LN metastases is tumor specific. Using flow cytometry and single-cell sequencing to perform comprehensive immune profiling, we identify multiple cellular mediators of tolerance. In particular, we find that LN metastases have the capacity to both resist NK cell cytotoxicity and induce regulatory T cells (Tregs). Furthermore, depletion of NK cells in vivo enables non-metastatic tumors to disseminate to LNs, and ablation of Tregs using FoxP3-DTR mice eliminates the occurrence of lymphatic metastases. Adoptive transfer of Tregs from the LNs of mice bearing LN metastasis to naïve mice facilitates metastasis in a manner that Tregs from mice without LN metastases cannot, and we find that these Tregs are induced in an antigen-specific manner. Whole exome sequencing revealed that neither the metastatic proclivity nor immunosuppression evolve through the acquisition of driver mutations, loss of neoantigens, loss of MHC class I presentation, or decreases in melanoma antigen expression. Rather, by RNA-seq and ATAC-seq, we show that a conserved interferon signaling axis is upregulated in LN metastases and is rendered stable through epigenetic reprogramming of chromatin accessibility resulting from chronic exposure to interferons in vivo. Furthermore, using CRISPR/Cas9, we find that these pathways are required for LN metastatic seeding, and validate their conserved significance in multiple mouse models and HNSCC patients with LN metastatic disease. Together, these findings demonstrate a critical role for LN metastasis in promoting tumor-specific immunosuppression. Citation Format: Nathan E. Reticker-Flynn, Weiruo Zhang, Pamela A. Basto, John B. Sunwoo, Sylvia K. Plevritis, Edgar G. Engleman. Lymph node colonization promotes distant tumor metastasis through the induction of tumor-specific immune tolerance [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Innovating through Basic, Clinical, and Translational Research; 2023 Jul 7-8; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2023;29(18_Suppl):Abstract nr PR01.

The adjuvant oxaliplatin-irinotecan paradox.

e15655 Background: A pervasive pattern in oncology is that chemotherapeutic agents which achieve acceptance for adjuvant use are the ones that have shown superior efficacy in the treatment of metastatic disease. The greater the efficacy in metastatic disease, the greater the likelihood that adjuvant use will be statistically viable. Oxaliplatin is the exception to this, having paradoxically shown similar outcomes to irinotecan in metastatic colorectal cancer (CRC) but superiority in the adjuvant setting. In this study, the TriNetX research database was used to better evaluate the adjuvant efficacy of oxaliplatin use in real-world patients. Methods: The TriNetX research database was used for this study. The TriNetX platform provides access to anonymized medical record information on more than 91 million patients in 75 large healthcare organizations. Three cohorts of stage III colorectal patients were created for comparison, utilizing International Classification of Disease-10 (ICD-10) codes and medication codes provided in the TriNetX platform. All patients were required to have a diagnosis of colon cancer (C18) and lymph node involvement (C77), with the absence of any liver or lung metastases (C78.7 and C78.0, respectively). Adjuvant oxaliplatin use was identified by the presence of the oxaliplatin medication code within 9 months of CRC diagnosis. The adjuvant oxaliplatin cohort was compared to a cohort with no oxaliplatin exposure, identified by the exclusion of the oxaliplatin medication code for 12 months following CRC diagnosis. The cohorts were balanced for age, race, gender, and ethnicity. The endpoint of the comparisons was all-cause mortality at 5 years. Results: Adjuvant use of oxaliplatin was associated with a 2.3% absolute decrease in the risk of death at 5 years (risk ratio 0.88, 95% CI (0.79,0.97), p-value 0.01). See figure 1. Conclusions: This study shows that adjuvant use of oxaliplatin is associated with a 2.3% absolute survival advantage in stage III colorectal cancer patients. This small absolute benefit is likely why occasional retrospective analyses have been unable to replicate it. A controlled interrupted time series analysis from Huang, et. al. showed no benefit to adjuvant oxaliplatin in the stage III setting for Taiwanese patients. Such a small benefit may also explain why the ACHIEVE trial found three months of adjuvant oxaliplatin to be equivalent to six. When a benefit is very small, a shorter duration of treatment would be more likely to result in statistical equivalency than if the benefit was more substantial. [Table: see text]

Periostin+ Stromal Cells Guide Lymphovascular Invasion by Cancer Cells.

Highly metastatic breast cancer cells activate a population of periostin-expressing CAFs that remodel the extracellular matrix to promote escape of cancer cells into lymphatic vessels and drive colonization of proximal lymph nodes.

Grape seed meal by-product is able to counteract oxidative stress induced by lipopolysaccharide and dextran sulphate in IPEC cells and piglets after weaning.

Oxidative stress is a pivotal factor in the pathogenesis of intestinal inflammation, leading to cellular damage and tissue injury. Natural antioxidants compounds found in agro-industrial by-products have proven their effectiveness in treatment of intestinal inflammation and oxidative stress, exhibiting many favourable effects. The aim of this study was to evaluate the capacity of a grape seed meal byproduct (GSM) to counteract the effects induced by E. coli lipopolysaccharide (LPS, 5μg/ml) in vitro on IPEC-1 cells and by dextran sulphate sodium (DSS, 1g/b.w./day) in vivo on piglets after weaning. Reactive oxygen species (ROS), pro-oxidant markers (malondialdehyde MDA, thiobarbituric acid reactive substances TBARS, protein carbonyl, DNA oxidative damage) antioxidant enzymes (catalase -CAT, superoxide dismutase -SOD, glutathione peroxidase -GPx, endothelial and inducible nitric oxide synthases -eNOS and iNOS) and several important components of Keap1/Nrf2 signalling pathway were analysed in IPEC-1 cells as well as in piglet's colon and lymph nodes. Our results demonstrated that GSM extract or 8% dietary GSM showed anti-oxidant properties counteracting the pro-oxidant response (ROS, MDA-TBARS, protein carbonyl, DNA/RNA damage) induced by LPS or DSS and restoring the levels of endogenous antioxidant enzymes, including CAT, SOD, GPx, eNOS and iNOS in colon and mesenteric lymph nodes. These beneficial effects were modulated via Nrf2 signalling pathway in both in vitro and in vivo studies.

Abstract 3469: Lymph node colonization promotes distant tumor metastasis through the induction of tumor-specific immune tolerance

Abstract The majority of cancer-associated deaths result from distant organ metastasis, yet the mechanisms that enable this process remain poorly understood. For most solid tumors, colonization of regional or distant lymph nodes (LNs) typically precedes the formation of distant organ metastases, yet it remains unclear whether LN metastasis plays a functional role in disease progression. LNs are major sites of anti-tumor lymphocyte education, including in the context of immunotherapy, yet LN metastasis frequently correlates with further disease progression. Here, we find that LN metastasis represents a critical step in tumor progression through the capacity of such metastases to induce tumor-specific immune tolerance in a manner that promotes further dissemination of tumors to distant organs. Using an in vivo passaging approach of a non-metastatic syngeneic melanoma, we generated 300 unique cell lines exhibiting varying degrees of LN metastatic capacity. We show that the presence of these LN metastases enables distant organ seeding of metastases in a manner that the parental tumor cannot, and this effect is eliminated in mice lacking an adaptive immune response. Furthermore, this promotion of distant seeding by LN metastases is tumor specific. Using flow cytometry and single-cell sequencing to perform comprehensive immune profiling, we identify multiple cellular mediators of tolerance. In particular, we find that LN metastases have the capacity to both resist NK cell cytotoxicity and induce regulatory T cells (Tregs). Furthermore, depletion of NK cells in vivo enables non-metastatic tumors to disseminate to LNs, and ablation of Tregs using FoxP3-DTR mice eliminates the occurrence of lymphatic metastases. Adoptive transfer of Tregs from the LNs of mice bearing LN metastasis to naïve mice facilitates metastasis in a manner that Tregs from mice without LN metastases cannot, and we find that these Tregs are induced in an antigen-specific manner. Whole exome sequencing revealed that neither the metastatic proclivity nor immunosuppression evolve through the acquisition of driver mutations, loss of neoantigens, loss of MHC class I presentation, or decreases in melanoma antigen expression. Rather, by RNA-seq and ATAC-seq, we show that a conserved interferon signaling axis is upregulated in LN metastases and is rendered stable through epigenetic reprogramming of chromatin accessibility resulting from chronic exposure to interferons in vivo. Furthermore, using CRISPR/Cas9, we find that these pathways are required for LN metastatic seeding, and validate their conserved significance in additional mouse models of pancreatic ductal adenocarcinoma and head and neck squamous cell carcinoma and humans with LN metastatic disease. Together, these findings demonstrate a critical role for LN metastasis in promoting tumor-specific immunosuppression. Citation Format: Nathan E. Reticker-Flynn, Weiruo Zhang, Julia A. Belk, Pamela A. Basto, Andrew J. Gentles, John B. Sunwoo, Ansuman T. Satpathy, Sylvia K. Plevritis, Edgar G. Engleman. Lymph node colonization promotes distant tumor metastasis through the induction of tumor-specific immune tolerance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3469.

Colonic T-cell-rich, large B-cell lymphoma associated with equid herpesvirus 5 infection and secondary trans-colonic fistula in a horse.

A 17-y-old Rocky Mountain gelding was presented to the Virginia-Maryland Veterinary Teaching Hospital because of a 4-wk history of anorexia, weight loss, lethargy, and fever of unknown origin. Abdominal ultrasound revealed lymphadenomegaly of the abdominal and colonic lymph nodes, thickening of the wall of the large colon, and a mass associated with the large colon. The horse was euthanized given a poor prognosis. On autopsy, an ~20-cm diameter mass was found within the mesocolon between the right ventral and right dorsal colon. The mass had invaded through the colonic walls and formed a fistula between the 2 involved lumina. On histologic evaluation, the mass consisted of small numbers of large neoplastic lymphocytes, numerous small lymphocytes, and many foamy macrophages. A diagnosis of T-cell-rich, large B-cell lymphoma was made based on immunohistochemical staining for CD79a, CD3, and Iba1; concurrent infection with equid herpesvirus 5 was confirmed with in-situ hybridization (ISH). To our knowledge, neither a trans-colonic fistula resulting from alimentary lymphoma in a horse nor detection of intralesional equid herpesvirus 5 in equine alimentary lymphoma by ISH has been reported previously.

The risk of lymph node metastasis in patients with T2 colon cancer.

It is often safe to treat pT1 tumours with local resection due to the low risk of lymph node metastasis. The risk of lymph node metastasis in pT2 colon cancer is less well investigated. The recommendation for patients diagnosed with T2 colon cancer is a segmental resection including regional lymph nodes. The aim of this work was to determine the risk of lymph node metastasis in pT2 colon cancer and identify the possible associated clinical and pathological risk factors for lymph node metastasis. PubMed and Embase were systematically searched for studies describing patients with T2 colon cancer and lymph node status after histopathological assessment. Lymph node metastasis and the effect of histological and clinical factors were included. Overall, 5489 studies were screened, and 10 studies consisting of a total of 91 460 patients were included in the review. The overall risk of lymph node metastasis was 19.3% (95% confidence interval 19.0%-19.5%). A meta-analysis was not possible as very few studies described the clinical and pathological risk factors for lymph node metastasis. The risk of lymph node metastasis in patients with pT2 colon cancers is higher than for pT1. The studies included patients operated on from 1985 to 2015 with variations in surgical procedure, pathological handling, and definition of lymph node metastasis. Further studies reporting risk factors for lymph node metastasis in pT2 colon cancer are warranted as more data are needed to determine if local resection for a subgroup of patients could be an alternative treatment modality.

Clinical, histopathological, and molecular findings for Mycobacterium avium subspecies paratuberculosis (MAP) in dairy goats under semiarid conditions

The objective of this study was to report the occurrence of Mycobacterium avium subspecies paratuberculosis (MAP) in dairy goats, via description of their clinical presentation, histopathological findings, and molecular identification of the infectious agent. Screening was performed using IS900 real-time PCR (qPCR) in milk samples from 179 properties in the semiarid of Northeast region of Brazil. Pooled milk samples from all lactating goats from processing plants were submitted to molecular diagnosis. One property had a positive result at qPCR. The production unit which had the positive sample for MAP was located, and an on-site visit to this property was performed to collect individual milk samples, seven of which tested MAP positive by IS900 qPCR. With permission from the owner, two goats (Animal 1 was positive and Animal 2 was negative on first qPCR for MAP) were acquired and euthanized. Animals 1 and 2 had milk and portions of the duodenum, ileum, colon, and mesenteric lymph nodes positive at qPCR for MAP. Animal 1 also had MAP DNA detected in part of the jejunum and cecum. In animal 2, the ileocecal valve tested positive. MAP was not detected in the blood or feces of either animal; however; it was confirmed for the association of clinical findings, histopathology, and qPCR. The gene IS900 from the positive samples were sequenced and showed a 99% similarity with MAP. The MAP was identified for the first time in the goat milk and tissues in the semiarid region of Northeast Brazil.

P015 CITE-seq analysis revealed immune cell diversity in colonic mesenteric lymph nodes from IBD patients

Abstract Background Mononuclear phagocytes (MNPs), including dendritic cells (DCs), monocytes (Mo), and macrophages (Mac), are key inducers of the adaptive immune response. MNPs could circulate between blood, mucosa, and mesenteric lymph nodes (MLNs), where they interact with T cells, natural killer (NK) cells, and innate lymphoid cells (ILC), contributing to chronic inflammation. MNPs have been previously investigated at the transcriptomic level in the inflamed gut mucosa, but their molecular characterization at the single-cell level remains uncovered in inflamed MLNs of patients with inflammatory bowel diseases (IBD). Methods MLNs were collected from surgical colonic resections of patients with Crohn’s disease (CD; n=3) or ulcerative colitis (UC; n=3). Cell suspensions were multiplexed and then pooled for sorting CD45+CD3+CD19- T cells and CD45+CD3-CD19- non-T/non-B cells by flow cytometry. Next, sorted cells were combined and labeled with BD Abseq antibodies (antibodies conjugated to oligonucleotide tag). CITE-seq (Cellular Indexing of Transcriptomes and Epitopes by Sequencing), combining simultaneous RNA and protein expression, was performed on the BD RhapsodyTM platform. Results High-quality data from 3308 captured single cells (1471 from CD and 1837 from UC) identified four main immune cell populations (myeloid DCs/Mo/Mac, plasmacytoid DCs, T cells, and NK/innate lymphoid cells). We further segregated cell subsets into 16 MNP, 4 NK/ILC, and 9 T cell clusters. MNP subsets were characterized according to specific gene expression (HLA-DRA, CD1c, ITGAX, SIRPA, JCHAIN, IL3RA). They revealed transcriptionally distinct DC clusters, including one cluster of mature regulatory DC (mregDC) (LAMP3, CCR7), one cluster expressing AXL and THBD, and one cluster of CD103+ DCs expressing LTB, FLT3, and IL22RA2. Further analysis of MNP subsets also revealed 6 clusters of monocytes and macrophages, including inflammatory Mo, Inflammatory Mac, and regulatory Mac. Overall, the proportion of myeloid cells and pDC was higher in UC MLNs when compared to CD (29.6% and 21.6% versus 17.1% and 11.7%, p<0.0001) while the proportion of NK/ILC was higher in CD MLNs (11.7% versus 24.9%, p<0.0001). Comparison of differentially expressed genes (fold-change>1.5) between CD and UC samples showed that CD MLNs were enriched in NK-specific marker genes (KLRD1, IL2RB, NKG7, GZMA). In UC, the majority of upregulated genes related to myeloid gene markers (THBS1, HLA-DQA1, HLA-DRA, VCAN, IL1B, JCHAIN, and CXCL8). Conclusion CITE-Seq analysis of the colonic MLNs of patients with active IBD suggests differences in immune cell landscape gene expression between CD and UC.

Abstract PR013: Lymph node colonization promotes distant tumor metastasis through the induction of tumor-specific immune tolerance

Abstract The majority of cancer-associated deaths result from distant organ metastasis, yet the mechanisms that enable this process remain poorly understood. For most solid tumors, colonization of regional or distant lymph nodes (LNs) typically precedes the formation of distant organ metastases, yet it remains unclear whether LN metastasis plays a functional role in disease progression. LNs are major sites of anti-tumor lymphocyte education, including in the context of immunotherapy, yet LN metastasis frequently correlates with further disease progression. Here, we find that LN metastasis represents a critical step in tumor progression through the capacity of such metastases to induce tumor-specific immune tolerance in a manner that promotes further dissemination of tumors to distant organs. Using an in vivo passaging approach of a non-metastatic syngeneic melanoma, we generated 300 unique cell lines exhibiting varying degrees of LN metastatic capacity. We show that the presence of these LN metastases enables distant organ seeding of metastases in a manner that the parental tumor cannot, and this effect is eliminated in mice lacking an adaptive immune response. Furthermore, this promotion of distant seeding by LN metastases is tumor specific. Using flow cytometry and single-cell sequencing to perform comprehensive immune profiling, we identify multiple cellular mediators of tolerance. In particular, we find that LN metastases have the capacity to both resist NK cell cytotoxicity and induce regulatory T cells (Tregs). Furthermore, depletion of NK cells in vivo enables non-metastatic tumors to disseminate to LNs, and ablation of Tregs using FoxP3-DTR mice eliminates the occurrence of lymphatic metastases. Adoptive transfer of Tregs from the LNs of mice bearing LN metastasis to naïve mice facilitates metastasis in a manner that Tregs from mice without LN metastases cannot, and we find that these Tregs are induced in an antigen-specific manner. Whole exome sequencing revealed that neither the metastatic proclivity nor immunosuppression evolve through the acquisition of driver mutations, loss of neoantigens, loss of MHC class I presentation, or decreases in melanoma antigen expression. Rather, by RNA-seq and ATAC-seq, we show that a conserved interferon signaling axis is upregulated in LN metastases and is rendered stable through epigenetic reprogramming of chromatin accessibility resulting from chronic exposure to interferons in vivo. Furthermore, using CRISPR/Cas9, we find that these pathways are required for LN metastatic seeding, and validate their conserved significance in additional mouse models of pancreatic ductal adenocarcinoma and head and neck squamous cell carcinoma and humans with LN metastatic disease. Together, these findings demonstrate a critical role for LN metastasis in promoting tumor-specific immunosuppression. Citation Format: Nathan E. Reticker-Flynn, Weiruo Zhang, Julia A. Belk, Pamela A. Basto, Andrew J. Gentles, John B. Sunwoo, Ansuman K. Satpathy, Sylvia K. Plevritis, Edgar G. Engleman. Lymph node colonization promotes distant tumor metastasis through the induction of tumor-specific immune tolerance [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr PR013.

Effects of Dietary Supplementation of Spirulina platensis on the Immune System, Intestinal Bacterial Microbiome and Skin Traits of Mink.

The impact of dietary inclusion of Spirulina platensis on the immune system, intestinal microbiome and skin of mink was investigated. Forty-eight animals were equally separated into four groups. Groups B and D were control animals, while groups A and C had their feed supplemented daily with 100 mg/kg of body weight Spirulina. Mink in groups A and B were descended from dams supplemented with spirulina during their reproductive period, while those in groups C and D were descended from dams fed the control diets. Fur growth rate and quality were graded semi-quantitatively. Fecal microbiome analysis, skin thickness histomorphometry, immunohistochemical labeling and counts of immune cells in the colon, mesenteric lymph nodes and spleen and quantitative gene expression analysis of cytokines in the colon were performed. Skin thickness, fur growth rate and skin quality were similar among groups (p > 0.05). However, differences were observed among groups concerning the relative and differential abundance of bacterial species. Tgf-β expression was lower in group A, whereas IL-β1 was lower in group C compared to group B (p < 0.05). Group D had significantly lower numbers of inflammatory cells in the colon and mesenteric lymph nodes. The results revealed that Spirulina decreased indices of subclinical inflammation in mink gut, while differences in the bacterial communities among groups were observed.

S2204 A Rare Case of Medullary Carcinoma of the Colon With Lymphatic Metastasis

Introduction: Medullary carcinoma of the colon (MAC) is a rare cancer encompassing only .03% of all colorectal carcinomas. We present a rare case of MAC occurring in an older adult with a strong tobacco use history. Case Description/Methods: A 76-year-old female with PMHx of tobacco use disorder, COPD, and known pulmonary nodules presented to the ED for surveillance of her pulmonary nodules. A review of systems was positive for chronic shortness of breath and cough. A CT scan of the chest revealed enlarging lung nodules and mediastinal adenopathy. A PET scan revealed a hypermetabolic 2.5 x 2.5 cm soft mass in the distal ascending colon and hypermetabolic lymph nodes in the right upper quadrant (Figure). Colonoscopy revealed an infiltrative 2 cm mass at the hepatic flexure, and pathology revealed an invasive, poorly differentiated adenocarcinoma with normal expression of MSH2 and MSH6 and absence of MLH1 and PMS2. These findings were consistent with medullary carcinoma of the colon. Endoscopic ultrasound with biopsy of peripancreatic and porta-hepatis lymph nodes favored metastatic medullary carcinoma. The patient underwent a right hemicolectomy and follows closely outpatient. Discussion: MAC is a rare cancer associated with a high level of microsatellite instability and deficient mismatch repair proteins. It is a non-gland forming cancer composed of large polygonal eosinophilic cells growing in solid sheets and infiltrated with small lymphocytes. The majority of reported cases revealed a lack of MLH-1 and PMS2, just as our patient did. They instead express markers that are not commonly associated with colorectal cancers, such as calretinin, CK7, SATB2, and CDH17. MACs were previously difficult to differentiate from poorly differentiated adenocarcinomas due to their unique tumor marker expression and histopathology. The current standard for diagnosis of MAC therefore requires distinct microscopic morphology and molecular staining patterns. There are no current treatment guidelines due to the rarity of MACs, although MACs do have a favorable prognosis when compared to other adenocarcinomas and surgical resection and FOLFOX chemotherapy have been used successfully in some studies. Although MACs have been sporadically reported in case reports, further studies are required to determine guidelines for both diagnosis and treatment of this rare disease.Figure 1.: Endoscopic Visualization with Final Needle Aspiration of Abnormal Lymph Node.