Homocysteine Triggers Mucosal Microvascular Activation in Inflammatory Bowel Disease

• Published in: The American journal of gastroenterology Vol. 100; no. 4; pp. 886 - 895
• Main Authors: Danese, Silvio, Sgambato, Alessandro, Papa, Alfredo, Scaldaferri, Franco, Pola, Roberto, Sans, Miquel, Lovecchio, Maria, Gasbarrini, Giovanni, Cittadini, Achille, Gasbarrini, Antonio
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing 01.04.2005; Wolters Kluwer Health Medical Research, Lippincott Williams & Wilkins
• Subjects: Adolescent; Adult; Aged; Biological and medical sciences; Chemokine CCL2 - blood; Colitis, Ulcerative - physiopathology; Crohn Disease - physiopathology; Endothelium, Vascular - physiopathology; Enzyme-Linked Immunosorbent Assay; Female; Flow Cytometry; Folic Acid - blood; Gastroenterology; Gastroenterology. Liver. Pancreas. Abdomen; Homocysteine - physiology; Humans; Inflammatory bowel disease; Intercellular Adhesion Molecule-1 - blood; Intestinal Mucosa - blood supply; Leukocyte Adherence Inhibition Test; Male; Medical sciences; Microcirculation - physiopathology; Middle Aged; Other diseases. Semiology; Reference Values; Stomach. Duodenum. Small intestine. Colon. Rectum. Anus; Tumor Necrosis Factor-alpha - metabolism; Vascular Cell Adhesion Molecule-1 - blood; Sulfur containing aminoacid; Crohn disease; Thiol; Trigger; Homocystein; Digestive diseases; Intestinal disease; Activation; Inflammatory disease; Ulcerative colitis
• ISSN: 0002-9270; 1572-0241
• DOI: 10.1111/j.1572-0241.2005.41469.x

Increased homocysteine contributes to the pathophysiology of several chronic inflammatory diseases. Whether homocysteine could participate in mucosal inflammation in inflammatory bowel disease (IBD) has not been explored yet. Our aims were to study the levels of plasma and mucosal homocysteine in IBD patients and to assess whether homocysteine can trigger an inflammatory reaction on human intestinal microvascular endothelial cells (HIMECs). Homocysteine was measured in the plasma, mucosal biopsy, and lamina propria mononuclear cell (LPMC) supernatants from normal and IBD subjects. HIMEC were cultured in presence of homocysteine, TNF-alpha, or folic acid, alone or in combination. Expression of vascular cell adhesion molecule 1 (VCAM-1) and intercellular cell adhesion molecule 1 was measured by flow cytometry and monocyte chemoattractant protein-1 (MCP-1) production by ELISA. Phosphorylation of p38 and p42/44 was assessed by immunoblot in HIMEC extracts. T-cell- and monocyte-HIMEC adhesion assays were used to evaluate the impact of homocysteine on leukocyte adhesion to intestinal endothelial cells. Patients with IBD displayed significantly higher homocysteine plasma and mucosal levels than control subjects. IBD-derived LPMC released higher homocysteine than control-derived LPMC. Treatment of HIMEC with homocysteine, and synergistically with the combination of TNF-alpha and homocysteine, triggered HIMEC inflammation, resulting in VCAM-1 up-regulation, MCP-1 production, and p38 phosphorylation. These events lead to an increased capacity of HIMEC to adhere T- and monocyte cells and were blocked by folic acid treatment. Homocysteine is increased in both the mucosa and plasma of patients with Crohn's disease and ulcerative colitis and contributes to the inflammatory state of the mucosal IBD endothelium. Therefore, homocysteine could play a proinflammatory role in IBD, which can be efficiently targeted by folic acid supplementation.