Celiac Disease (CD) represents an autoimmune disorder triggered by the exposure to gluten in genetically susceptible individuals. Recent studies suggest the involvement of macrophages in CD pathogenesis. Macrophages are immune cells, present as pro-inflammatory classically activated macrophages (M1) or as anti-inflammatory alternatively activated macrophages (M2). The Cannabinoid Receptor 2 (CB2) has important anti-inflammatory and immunoregulatory properties. We previously demonstrated that a common CB2 functional variant, Q63R, causing CB2 reduced function, is associated with several inflammatory and autoimmune diseases The first aim of this study was to investigate the phenotype of macrophages isolated from peripheral blood of CD patients and CB2 expression. The second aim was to evaluate the effects of CB2 pharmacological modulation on CD macrophage polarization. Moreover, by an in vitro model of “immunocompetent gut” we investigated the role of CD macrophages in inducing intestinal barrier damage and the possibility to restore its functionality modulating their polarization. We found an increased expression of M1 macrophages and a CB2 reduced expression. We also demonstrated CD M1 macrophages in inducing the typical mucosal barrier damage of CD. CB2 stimulation switches macrophage polarization towards the anti-inflammatory M2 phenotype thus reducing inflammation but also limiting the epithelial dysfunction. Therefore, we suggest CB2 receptor as a possible novel therapeutic target for CD by regulating macrophages polarization and by preventing mucosal barrier damage.

Macrophages play a crucial role in maintaining intestinal homeostasis and can exhibit either pro-inflammatory M1 or anti-inflammatory M2 phenotypes. The cannabinoid receptor type 2 (CB2) is involved in immune regulation and may represent a therapeutic target in inflammatory bowel disease (IBD). Our study investigates the phenotype of circulating macrophages and CB2 expression in children with IBD, assessing the role of CB2 stimulation in macrophage polarization, iron metabolism, and intestinal barrier function. Macrophages were isolated from 17 children with ulcerative colitis (UC), 21 with Crohn’s disease (CD), and 12 healthy controls (CTR). Cells were treated with a CB2 agonist (JWH-133) and an inverse agonist (AM630). CB2 expression and macrophage polarization were assessed by Western blot. Iron metabolism was evaluated through IL-6, hepcidin levels, FPN-1 expression, and iron concentration. Inflammation was assessed by cytokine release. An in vitro “immunocompetent gut” model was used to study the effects of CB2 stimulation on macrophage polarization and intestinal barrier function. CB2 expression was reduced in IBD macrophages. Compared to controls, IBD patients showed increased M1 markers and pro-inflammatory cytokines, with a reduction in M2 markers and IL-13. Altered iron metabolism was observed, with increased [Fe³⁺], hepcidin release, and DMT1 expression, and reduced FPN-1. CB2 stimulation restored iron metabolism, induced M2 polarization, and improved intestinal barrier function. CB2 could represent a novel therapeutic target for IBD by modulating macrophage function, iron metabolism, and mucosal barrier restoration.

The diagnosis and monitoring of eosinophilic esophagitis (EoE), a common pediatric pathology, typically involves invasive procedures such as an upper endoscopy with biopsies, imposing a significant burden on patients and healthcare systems. We aimed to assess miR-21-5p and miR-223-3p levels in pediatric EoE patients and evaluate their as potential non-invasive biomarkers of disease activity and response to treatments. We enrolled 13 children with EoE and 8 controls. Plasma and esophageal mucosa samples from patients were collected at diagnosis and after 8–10 weeks of therapy and compared with control samples. After microRNA(miRNA) extraction, the levels of miR-21-5p and miR-223-3p and their relevant target genes were analyzed. Bioinformatic analysis was used to identify the predicted target genes and pathways that are potentially relevant for disease pathophysiology. Plasma levels of miR-21-5p and miR-223-3p were significantly higher in EoE patients than in the controls, reflecting their levels in esophageal mucosa. The target genes of these miRNAs are involved in key signaling pathways (MAPK, Ras, and FoxO), relevant for EoE pathophysiology. Among these, STAT3 (Signal Transducer and Activator of Transcription 3) and PTEN (Phosphatase and Tensin Homolog), which are significantly downregulated in patient esophageal mucosa, are implicated in eosinophilic gastroenteropathies and autoimmune diseases. Following therapy (proton pump inhibitors and/or fluticasone propionate), plasma and tissue expression of both miRNAs significantly decreased and were no longer different from the controls. These microRNAs may serve as complementary non-invasive EoE markers and reduce the need for endoscopy/biopsies.

Crohn's disease (CD) is an inflammatory gastrointestinal disorder marked by impaired autophagy due to inefficient bacterial uptake. We studied the effects of autophagy modulation using Tat-beclin-1 and carbamazepine (CBZ) on dendritic cells (DCs) and Paneth cell functionality in pediatric CD patients. Twenty CD children genotyped for the ATG16L1 rs2241880 polymorphism and 10 healthy controls were enrolled. DCs were incubated with fluorochrome-conjugated particles of Escherichia coli or DQ-ovalbumin after pretreatment with CBZ or Tat-beclin-1 to evaluate antigen processing. Treated DCs were stained for P62, LAMP1, and LC3, and analyzed by confocal microscopy. Paneth cells from biopsies were pretreated with both drugs, stained for lysozyme, and analyzed by transmission electron microscopy. Antigen processing increased after Tat-beclin-1 and CBZ treatment in all groups. DCs expressed higher activation markers HLA-DR and CD86+, notably in high-risk patients, who also showed increased DQ-OVA processing. The number of lysozymes in Paneth cells from controls did not change after Tat-beclin-1 treatment, while in the CD group, it decreased significantly, suggesting increased exocytosis. CBZ treatment increased secretory granules only in CD inflamed tissue. Our results indicate that CBZ and Tat-beclin-1 enhance autophagic flux, representing a novel approach to treating pediatric CD patients.