The DSL-6A/C1 murine pancreatic ductal adenocarcinoma (PDAC) tumor model was established in Lewis rats and characterized through a comprehensive multiparametric analysis to compare it to other preclinical tumor models and explore potential diagnostic and therapeutical targets. DSL-6A/C1 tumors were histologically analyzed to elucidate PDAC features. The tumor microenvironment was studied for immune cell prevalence. Multiparametric MRI and PET imaging were utilized to characterize tumors, and 68Ga-FAPI-46-targeting cancer-associated fibroblasts (CAFs), were used to validate the histological findings. The histology confirmed typical PDAC characteristics, such as malformed pancreatic ductal malignant cells and CAFs. Distinct immune landscapes were identified, revealing an increased presence of CD8+ T cells and a decreased CD4+ T cell fraction within the tumor microenvironment. PET imaging with 68Ga-FAPI tracers exhibited strong tracer uptake in tumor tissues. The MRI parameters indicated increasing intralesional necrosis over time and elevated contrast media uptake in vital tumor areas. We have demonstrated that the DSL-6A/C1 tumor model, particularly due to its high tumorigenicity, tumor size, and 68Ga-FAPI-46 sensitivity, is a suitable alternative to established small animal models for many forms of preclinical analyses and therapeutic studies of PDAC.

Bordetella bronchiseptica (Bb) is a Gram-negative bacterium responsible for canine infectious respiratory disease complex (CIRDC). Several vaccines targeting this pathogen are currently licensed for use in dogs, but their mechanism of action and the correlates of protection are not fully understood. To investigate this, we used a rat model to examine the immune responses induced and the protection conferred by a canine mucosal vaccine after challenge. Wistar rats were vaccinated orally or intranasally on D0 and D21 with a live attenuated Bb vaccine strain. At D35, the rats of all groups were inoculated with 103 CFU of a pathogenic strain of B. bronchiseptica. Animals vaccinated via either the intranasal or the oral route had Bb-specific IgG and IgM in their serum and Bb-specific IgA in nasal lavages. Bacterial load in the trachea, lung, and nasal lavages was lower in vaccinated animals than in non-vaccinated control animals. Interestingly, coughing improved in the group vaccinated intranasally, but not in the orally vaccinated or control group. These results suggest that mucosal vaccination can induce mucosal immune responses and provide protection against a Bb challenge. This study also highlights the advantages of a rat model as a tool for studying candidate vaccines and routes of administration for dogs.

The use of antibiotics as well as changes in the gut microbiota have been linked to development of food allergy in childhood. It remains unknown whether administration of a single clinically relevant antibiotic directly promotes food allergy development when administrated during the sensitisation phase in an experimental animal model. We investigated whether the antibiotic amoxicillin affected gut microbiota composition, development of cow's milk allergy (CMA) and frequencies of allergic effector cells and regulatory T cells in the intestine. Brown Norway rats were given daily oral gavages of amoxicillin for six weeks and whey protein concentrate (WPC) with or without cholera toxin three times per week for the last five weeks. Microbiota composition in faeces and small intestine was analysed by 16S rRNA sequencing. The development of CMA was assessed by WPC-specific IgE in serum, ear swelling response to WPC and body hypothermia following oral gavage of WPC. Allergic effector cells were analysed by histology, and frequencies of regulatory and activated T cells were analysed by flow cytometry. Amoxicillin administration reduced faecal microbiota diversity, reduced the relative abundance of Firmicutes and increased the abundance of Bacteroidetes and Proteobacteria. Despite these effects, amoxicillin did not affect the development of CMA, nor the frequencies of allergic effector cells or regulatory T cells. Thus, amoxicillin does not carry a direct risk for food allergy development when administrated in an experimental model of allergic sensitisation to WPC via the gut. This finding suggests that confounding factors may better explain the epidemiological link between antibiotic use and food allergy.
© 2022 The Authors. Scandinavian Journal of Immunology published by John Wiley & Sons Ltd on behalf of The Scandinavian Foundation for Immunology.

Meningeal lymphatics near the cribriform plate undergo lymphangiogenesis during neuroinflammation to drain excess fluid. Here, we hypothesized that lymphangiogenic vessels may acquire an altered phenotype to regulate immunity. Using single-cell RNA sequencing of meningeal lymphatics near the cribriform plate from healthy and experimental autoimmune encephalomyelitis in the C57BL/6 model, we report that neuroinflammation induces the upregulation of genes involved in antigen presentation such as major histocompatibility complex class II, adhesion molecules including vascular cell adhesion protein 1 and immunoregulatory molecules such as programmed cell death 1 ligand 1, where many of these changes are mediated by interferon-γ. The inflamed lymphatics retain CD11c+ cells and CD4 T cells where they capture and present antigen, creating an immunoregulatory niche that represents an underappreciated interface in the regulation of neuroinflammation. We also found discontinuity of the arachnoid membrane near the cribriform plate, which provides unrestricted access to the cerebrospinal fluid. These findings highlight a previously unknown function of local meningeal lymphatics in regulating immunity that has only previously been characterized in draining lymph nodes.
© 2022. The Author(s), under exclusive licence to Springer Nature America, Inc.

Meningeal lymphatic vessels residing in the dural layer surrounding the dorsal regions of the brain, basal regions, and near the cribriform plate have all been implicated in the management of neuroinflammation and edema. Interestingly, only the lymphatic vessels near the cribriform plate undergo functional lymphangiogenesis in a mouse model of Multiple Sclerosis, suggesting these particular lymphatics uniquely undergo dynamic changes in response to neuroinflammation and may have distinct access to pro-lymphangiogenic factors in the CNS. However, it is unknown if these newly formed lymphangiogenic vessels are functionally similar to steady-state or if they have any other functional changes during neuroinflammation. In this study, we generated a novel protocol to isolate lymphatic endothelial cells from the cribriform plate for single cell analysis. We demonstrate that neuroinflammation-induced lymphangiogenic vessels undergo unique changes, including the capture of CNS-derived antigens, upregulation of adhesion and immune-modulatory molecules to interact with dendritic cells, and display IFN-γ dependent changes in response to the microenvironment. Single-cell trajectory analysis showed that cribriform plate lymphangiogenic vessels are post-proliferative and not generated from trans-differentiation of myeloid cells. Additionally, we show that these lymphangiogenic vessels have access to a CSF reservoir, express the water pore Aquaporin-1, and may have direct access to the CSF due to gaps in the arachnoid epithelial layer separating the dura from the subarachnoid space. These data characterize cribriform plate lymphatics and demonstrate that these vessels are dynamic structures that engage in leukocyte interactions, antigen sampling, and undergo expansion to drain excess fluid during neuroinflammation. Neuroinflammation not only induces efficient drainage of CSF but also alters the functions of lymphatic vessels near the cribriform plate.