In the human and veterinary fields, oral vaccines generate considerable interest. In dogs, these vaccines are newly developed, and understanding their mechanisms is crucial. Mesenteric lymph nodes (MLNs) and Peyer\'s patches (PPs) are important sites for gastrointestinal mucosal induction, yet canine MLNs lack sufficient information. To address this, we collected MLN samples from healthy dogs, performed flow cytometry to characterize immune cells, and conducted single-cell RNA sequencing (scRNA-seq) to explore subpopulations, particularly B and T lymphocytes. This effort enabled the characterization of canine MLN\'s main cell populations and the construction of a predictive atlas, as well as the identification of particularities of this area.

BACKGROUND: Inflammatory bowel disease, particularly Crohn\'s disease (CD), has been associated with alterations in mesenteric adipose tissue (MAT) and the phenomenon termed \"creeping fat\". Histopathological evaluations showed that MAT and intestinal tissues were significantly altered in patients with CD, with these tissues characterized by inflammation and fibrosis.
OBJECTIVE: To evaluate the complex interplay among MAT, creeping fat, inflammation, and gut microbiota in CD.
METHODS: Intestinal tissue and MAT were collected from 12 patients with CD. Histological manifestations and protein expression levels were analyzed to determine lesion characteristics. Fecal samples were collected from five recently treated CD patients and five control subjects and transplanted into mice. The intestinal and mesenteric lesions in these mice, as well as their systemic inflammatory status, were assessed and compared in mice transplanted with fecal samples from CD patients and control subjects.
RESULTS: Pathological examination of MAT showed significant differences between CD-affected and unaffected colons, including significant differences in gut microbiota structure. Fetal microbiota transplantation (FMT) from clinically healthy donors into mice with 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced CD ameliorated CD symptoms, whereas FMT from CD patients into these mice exacerbated CD symptoms. Notably, FMT influenced intestinal permeability, barrier function, and levels of proinflammatory factors and adipokines. Furthermore, FMT from CD patients intensified fibrotic changes in the colon tissues of mice with TNBS-induced CD.
CONCLUSIONS: Gut microbiota play a critical role in the histopathology of CD. Targeting MAT and creeping fat may therefore have potential in the treatment of patients with CD.

UNASSIGNED: Transmesentric hernias are a type of internal hernia, in which there is herniation of bowel loops through a defect in the mesentery. They present with a wide variety of symptoms without any specific radiological features, leading to a delay in diagnosis and high mortality rate. Here, we present a case series of four patients with this rare but fatal cause of small bowel obstruction. Three children presented to the emergency department with small bowel obstruction. The other baby was a preterm neonate with an antenatal scan showing small bowel obstruction. All children underwent emergency laparotomy and were found to have a mesenteric defect with herniation and gangrene of the small bowel. Resection anastomosis of the gangrenous segment and closure of the mesenteric defect were done. The differential for small bowel obstruction in children should include transmesentric hernia. Laboratory or imaging investigations are often inconclusive. Timely exploration can save lives in this rare but life-threatening condition.

BACKGROUND: Heterotopic mesenteric ossification (HMO) is a clinically rare condition characterized by the formation of bone tissue in the mesentery. The worldwide reporting of such cases is limited to just over 70 instances in the medical literature. The etiology of HMO remains unclear, but the disease is possibly induced by mechanical trauma, ischemia, or intra-left lower quadrant abdominal infection, leading to the differentiation of mesenchymal stem cells into osteoblasts. Here, we present a rare case of HMO that occurred in a 34-year-old male, who presented with left lower quadrant abdominal pain.
METHODS: We report the case of a 34-year-old male patient who presented with left lower abdominal pain following trauma to the left lower abdomen. He subsequently underwent surgical treatment, and the postoperative pathological diagnosis was HMO.
CONCLUSIONS: We believe that although there is limited literature and research on HMO, when patients with a history of trauma or surgery to the left lower abdomen present with corresponding imaging findings, clinicians should be vigilant in distinguishing this condition and promptly selecting appropriate diagnostic and therapeutic interventions.

In this report, we present an Asian male patient who was 30 years old and admitted to the hospital due to pancreatitis. While undergoing a CT scan, an isolated mass was unexpectedly discovered in the patient\'s abdomen. The patient\'s abdominal pain, which was caused by pancreatitis, had resolved before he underwent surgical resection to remove the mass. Subsequently, the patient was diagnosed with Castleman disease based on pathology. Castleman disease occurring in the mesentery is exceptionally rare. Therefore, we have reviewed the essential information regarding Castleman disease and have found that the crucial part lies in the diagnosis and the consideration of distinct treatment strategies based on different types.

BACKGROUND: Diffuse intestinal and mesenteric lipomatosis is a rare condition characterized by the overgrowth of adipose tissue in the intestines and mesentery. This case report aims to highlight the rare occurrence of chronic abdominal distention caused by this disease and its unique invasion into the muscle layer, which has not been previously reported.
METHODS: A 36-year-old woman with a 7-year history of abdominal distension was admitted to our hospital\'s Department of Gastrointestinal Surgery.
METHODS: Abdominal and pelvic computed tomography revealed diffuse small intestinal lipomatosis.
METHODS: The patient underwent surgery. We performed an open-field ilectomy involving removal of all lipomatous intestines (250 cm).
RESULTS: During the surgery, diffuse nodular ileal and mesenteric lipomatosis was confirmed, characterized by the presence of multiple nodular lipomas within the submucosal and muscular layers. The surgical intervention involved the resection of 250 cm of the affected ileum, followed by jejunoileal anastomosis. Postoperative pathology confirmed the diagnosis, with lesions observed in both the submucosa and muscle layers. The patient showed significant improvement in symptoms, with normal intestinal function and weight gain observed over a 10-month follow-up period, and no signs of recurrence.
CONCLUSIONS: Diffuse intestinal and mesenteric lipomatosis can lead to long-term abdominal distension. Additionally, it may be involved in the muscle layer of the intestinal wall. Surgery is the primary treatment option for symptomatic intestinal lipomatosis.

In female Wistar rats with breast cancer, quantitative changes of pro-oncogenic miRNAs (miR-21, -27a, and -221) and tumor-suppressive miR-429 in the mesenteric lymph node were assessed after photodynamic therapy for breast cancer and after photodynamic therapy followed surgical treatment. The level of pro-oncogenic miR-221 in the mesenteric lymph node decreased, and the level of pro-oncogenic miR-21 increased after photodynamic therapy for breast cancer followed by surgical treatment in comparison with the corresponding parameters after photodynamic therapy alone. The content of tumor-suppressive miR-429 remained reduced, as in the group of animals receiving photodynamic therapy alone.

UNASSIGNED: The intestinal immune system plays a pivotal role in the induction of immune responses against food. In the case of T cell response, dendritic cells (DCs) are especially important. However, the regulation of immune responses to food by intestinal DCs has been poorly described. In this study, we analyzed the effect of Lactococcus lactis subsp. cremoris YRC3780, a lactic acid bacterial strain isolated from kefir, a traditional fermented milk product, on the immune responses induced by antigen presentation by intestinal DCs to T cells as well as the mechanism of action of these immunomodulatory effects. It has been shown that L. cremoris YRC3780 ameliorates the symptoms of pollinosis in both animal and human studies.
UNASSIGNED: CD11c+ cells from mesenteric lymph nodes (MLNs) of BALB/c mice were cultured as MLN DCs with L. cremoris YRC3780 and expression of genes inducing regulatory T cells (Tregs) was examined by qPCR. In addition, MLN DCs were cocultured with CD4+ T cells from DO11.10 transgenic mice expressing an ovalbumin (OVA)-specific TCR and the OVA antigen peptide and L. cremoris YRC3780. Induction of Tregs was examined by flow cytometry, gene expression was analyzed by DNA microarray and qPCR, and the production of cytokines was measured by ELISA. MLN DCs from TLR2-deficient mice and components of L. cremoris YRC3780 were used to examine the recognition of YRC3780 by MLN DCs.
UNASSIGNED: L. cremoris YRC3780 enhanced the expression of genes involved in Treg induction in MLN DCs and induced Foxp3+CD4+T cells in an MLN DC and CD4+ T-cell co-culture system. The effect on MLN DCs was likely mediated by receptors other than TLR2. Together with microarray analyses of CD4+ T cell gene expression and cytokine ELISA, it was demonstrated that L. cremoris YRC3780 promoted the induction of Th1 and Tregs, and regulated the balance of Th1/Th2 and Treg/Th17 cells involving multiple genes via the antigen-presentation of MLN DCs.
UNASSIGNED: Our findings provide insights into the modulation of intestinal immune responses mediated by DCs and the antiallergic effects of lactic acid bacteria.

BACKGROUND: Retrospective research suggests that excision of the affected mesentery can improve outcomes after an ileocoecal resection in Crohn\'s disease. However, prospective data from randomised controlled trials are scarce. We aimed to compare rates of postoperative recurrence in patients with Crohn\'s disease who underwent extended mesenteric resection.
METHODS: This international, randomised controlled trial was done in six hospitals and tertiary care centres in the Netherlands and Italy. Eligible patients were aged 16 years or older and had Crohn\'s disease that was previously confirmed by endoscopy in the terminal ileum or ileocolic region (L1 or L3 disease), with an imaging update in the past 3 months (ultrasound, MRI, or CT enterography). Eligible patients were scheduled to undergo primary ileocolic resection with ileocolic anastomosis. Enrolled patients were assigned by use of simple random allocation (1:1) to either extended mesenteric resection (intervention) or conventional mesenteric sparing resection (control). The primary endpoint was endoscopic recurrence 6 months after surgery. Analyses were done in all patients with primary endpoint data, excluding those who had no anastomosis, a postoperative diagnosis other than Crohn\'s disease, or withdrew consent. This trial was registered with ClinicalTrials.gov, NCT04538638.
RESULTS: Between Feb 19, 2020, and April 24, 2023, we assessed 217 patients for eligibility. 78 patients were excluded due to failure to meet the inclusion criteria or refusal to participate. 139 patients were enrolled and randomly assigned to either extended mesenteric resection (n=71) or mesenteric sparing resection (n=68). All 139 patients underwent surgery. Six patients were excluded after random assignment due to withdrawal of consent (n=2), postoperative diagnosis other than Crohn\'s disease (n=2) and no anastomosis performed (in case of a stoma; n=2). Two patients were lost to follow-up, and two more patients deviated from the protocol by undergoing investigations other than endoscopy 6 months after. 133 patients were included in the baseline analysis (67 in the extended resection group and 66 in the sparing resection group) of whom 57 (43%) were male. Baseline characteristics were similar between the groups, and median patient age was 36 years (IQR 25-54). 131 patients were analysed for the primary outcome. There was no difference between groups in the rate of endoscopic recurrence at 6 months after surgery (28 [42%] of 66 patients in the extended mesenteric resection group vs 28 [43%] of 65 patients in the mesenteric sparing resection group, relative risk 0·985, 95% CI 0·663-1·464; p=1·0). Five (8%) of 66 patients in the extended mesenteric resection group had anastomotic leakage within the 30 days after surgery, as did one (2%) of 65 in the mesenteric sparing group. Postoperative complications of Clavien-Dindo grade IIIa or higher were reported in seven (11%) patients in the mesenteric resection group and five (8%) in the mesenteric sparing group.
CONCLUSIONS: Extended mesenteric resection was not superior to conventional resection with regard to endoscopic Crohn\'s disease recurrence. These data support the guideline-recommended mesenteric sparing approach.
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