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.

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.

UNASSIGNED: Mesenteric panniculitis (MP) is an uncommon non-neoplastic idiopathic inflammation of adipose tissue, mainly affecting the mesentery of the small intestine, with its etiology remaining largely speculative. The difference in prevalence of MP among females and males varies across multiple studies. In most cases, MP is asymptomatic; however, patients can present with nonspecific abdominal symptoms or can mimic underlying gastrointestinal and abdominal diseases. The diagnosis is suggested by computed tomography and is usually confirmed by surgical biopsies if necessary. Treatment is generally supportive and based on a few selected drugs, namely, nonsteroidal anti-inflammatory drugs or corticosteroids. Surgery is reserved when the diagnosis is unclear, when malignancy is suspected or in the case of severe presentation such as mass effect, bowel obstruction, or ischemic changes.
UNASSIGNED: MP is a rare inflammatory condition of the mesentery often asymptomatic but can cause nonspecific abdominal symptoms. Diagnosis relies on computed tomography imaging, with treatment mainly supportive, utilizing medications like nonsteroidal anti-inflammatory drugs or corticosteroids, while surgery is reserved for severe cases or diagnostic uncertainty.
UNASSIGNED: MP causes abdominal pain, and it is mainly diagnosed with CT scan.

BACKGROUND: Mesenchymal stem cells (MSCs) demonstrate a wide range of therapeutic capabilities in the treatment of inflammatory bowel disease (IBD). The intraperitoneal injection of MSCs has exhibited superior therapeutic efficacy on IBD than intravenous injection. Nevertheless, the precise in vivo distribution of MSCs and their biological consequences following intraperitoneal injection remain inadequately understood. Additional studies are required to explore the correlation between MSCs distribution and their biological effects.
METHODS: First, the distribution of human umbilical cord MSCs (hUC-MSCs) and the numbers of Treg and Th17 cells in mesenteric lymph nodes (MLNs) were analyzed after intraperitoneal injection of hUC-MSCs. Subsequently, the investigation focused on the levels of transforming growth factor beta1 (TGF-β1), a key cytokine to the biology of both Treg and Th17 cells, in tissues of mice with colitis, particularly in MLNs. The study also delved into the impact of hUC-MSCs therapy on Treg cell counts in MLNs, as well as the consequence of TGFB1 knockdown hUC-MSCs on the differentiation of Treg cells and the treatment of IBD.
RESULTS: The therapeutic effectiveness of intraperitoneally administered hUC-MSCs in the treatment of colitis was found to be significant, which was closely related to their quick migration to MLNs and secretion of TGF-β1. The abundance of hUC-MSCs in MLNs of colitis mice is much higher than that in other organs even the inflamed sites of colon. Intraperitoneal injection of hUC-MSCs led to a significant increase in the number of Treg cells and a decrease in Th17 cells especially in MLNs. Furthermore, the concentration of TGF-β1, the key cytokine for Treg differentiation, were also found to be significantly elevated in MLNs after hUC-MSCs treatment. Knockdown of TGFB1 in hUC-MSCs resulted in a noticeable reduction of Treg cells in MLNs and the eventually failure of hUC-MSCs therapy in colitis.
CONCLUSIONS: MLNs may be a critical site for the regulatory effect of hUC-MSCs on Treg/Th17 cells and the therapeutic effect on colitis. TGF-β1 derived from hUC-MSCs promotes local Treg differentiation in MLNs. This study will provide new ideas for the development of MSC-based therapeutic strategies in IBD patients.

BACKGROUND: Internal hernia (IH) after Roux-Y gastric bypass (RYGB) can lead to extended small bowel ischemia if it not recognized and treated promptly. The aim of this study is to show whether improvement in mesenteric defect (MD) closure reduces the incidence of IH.
METHODS: Retrospective analysis of prospectively collected data from our database including all patients who underwent laparoscopic RYGB between 1999 and 2015. The usual technique was a retrocolic/retrogastric RYGB. We divided patients in four groups according to the closure technique for MD and compared incidences of IH between groups. All patients had at least 8 years of follow-up.
RESULTS: A total of 1927 patients (1497 females/460 males, mean age of 41.5 ± 11 years) were operated. A retrocolic/retrogastric RYGB was performed in 1747 (90.7%) and an antecolic RYGB in 180 patients. Mean duration of follow-up was 15 (8-24) years. 111 patients (5.8%) developed IH, the majority through the jejunojejunostomy (JJ, 3.7%) and Petersen (1.7%) defects. With improvement of closure technique, the incidence decreased over time, from 12.9% in the group with separate sutures to 1.05% in the most recent group with running non-absorbable sutures and an additional purse-string at the JJ defect (p < 0.0001).
CONCLUSIONS: Meticulous closure of MD during RYGB is a very important step that significantly reduces the IH risk after RYGB, even with a retrocolic/retrogastric anatomy. Using running non absorbable braided sutures and an additional purse-string suture at the JJ is the most effective technique, but a small IH risk persists. A high index of suspicion remains necessary in patients who present with acute abdominal pain after RYGB.